Re: Variables
Richard Blackwood wrote: Bengt Richter wrote: On Sat, 23 Apr 2005 22:45:14 -0400, Richard Blackwood <[EMAIL PROTECTED]> wrote: Robert Kern wrote: Richard Blackwood wrote: To All: Folks, I need your help. I have a friend who claims that if I write: foo = 5 then foo is NOT a variable, necessarily. If you guys can define for me what a variable is and what qualifications you have to back you, I can pass this along to, hopefully, convince him that foo is indeed a variable. None of us can do that unless you tell us what he thinks the word "variable" means. The terminology is a bit fluid. I suspect that your friend applying a somewhat restricted notion of "variable" that coincides with the behavior of variables in some other language. Indeed, this language is math. My friend says that foo is a constant and necessarily not a variable. If I had written foo = raw_input(), he would say that foo is a variable. Which is perfectly fine except that he insists that since programming came from math, the concept of variable is necessarily the identical. This can not be true. For example, I may define foo as being a dictionary, but I can not do this within math because there is no concept of dictionaries within mathematics; yet foo is a variable, a name bound to a value which can change. Maybe he doesn't know that foo = 5 in Python is not an equation as in math, but a Python source language statement to be translated to a step in some processing sequence. Tell him in Python foo is a member of one set and 5 is a member of another, and foo = 5 expresses the step of putting them into correspondence to define a mapping, not declaring them equal. Could I honestly argue this to him? From what basis do I argue that it is not an equation? It's his responsibility to show that it *is* an equation. x = x + 1 Equation? I think not. In any event, he would likely (passionately) disagree considering his notion that programming is an off-shoot of math and thus at the fundamental level has identical concepts and rules. Believe it or not, he used to be a programmer. Back in the day (while I was getting my PhD in philosophy), he was a employed programmer using Cobol, Fortran, and other languages like that. Okay, I take back my comment that this is not his field. I instead put forth the contention that he is a stark raving nutter. My qualifications to back me are that I cut my USENET teeth at talk.origins. I know my stark raving nutters. Did his seemingly peculiar definition of variable exist at that time? Oh, I'm sure *some* programming textbook from that time has tried to use such a definition and maintained the assertion that "programming is an off-shoot of math and thus at the fundamental level has identical concepts and rules." Both are rather naive, though, and the rest of the field has grown out of it. Your friend hasn't, it seems. Leave him to it, I say. If you insist on convincing him, however, you can point him to Raphael Finkel's _Advanced Programming Language Design_[1], page 5 which defines "variables" as "named memory locations." In this formal context, what we often informally call "variables" in Python aren't. This is why we sometimes use the term "names" instead. In C, when I declare a variable, I also specify a piece of memory to which that name refers. When I assign a value to that variable, the value goes into that memory location. When I assign a new value there, I overwrite the data in that memory location with the new value. It doesn't work like that in Python. The name just points to the new object. No memory gets overwritten. Your friends other assertions suggest that this is not what he is talking about, though. As always in terminology issues, what is correct depends on the conversation one is having. If I'm talking about a piece of Python code a colleague and I say, "so I put the value in a temporary variable--" and he says "No, it's not a variable, it's a name!", he has just volunteered for a severe beating. If I'm talking about comparative language design like Finkel is, the distinction is quite useful and no beatings need occur. None of this has anything to do with the terminology as it is used in mathematics. [1] http://www.nondot.org/sabre/Mirrored/AdvProgLangDesign/ -- Robert Kern [EMAIL PROTECTED] "In the fields of hell where the grass grows high Are the graves of dreams allowed to die." -- Richard Harter -- http://mail.python.org/mailman/listinfo/python-list
Re: Variables
>>In mathematics, the word 'variable' is generally an undefined meta-term >>that is *notorious* for having multiple possible meanings and shades of >>meaning. One mathematician/linguist once claimed to have discerned >>somewhere around 15 different meanings and shades thereof. >> > What is his/her name? Wish I could remember but this was some decades ago. But you should be able to think a few yourself. Terry J. Reedy -- http://mail.python.org/mailman/listinfo/python-list
Re: Variables
Richard Blackwood wrote: He would argue strongly against your notion of variable. In the statement "foo = 5", foo is constant. He would thus argue that foo is a constant and not a variable (regardless of whether you change foo's value in subsequent statements). Sounds like his mind is made up and you will probably not be able to persuade him otherwise. But maybe this will help... or not. ;-) Given a math equation... x = 2y+3 x and y are clearly (most would agree) variables. The value of each changes depending on the value of the other. To solve the equation you set one variable to a value to find the other. x = 2*y+3 y = 5 x = 2*5+3 x = 13 Do this again for other values... etc... Would he agree that x, and y are variables even after a value is determined? Or would he say that they become constants once you decide a value for one? I think context is the deciding factor if this is a general discussion concerning math equations. The above equation may be an equation of a line, or it may be the equation of a specific condition with two unknowns. They may variables which may either have the value which is constant, a known value, an unknown value, or a range of values. So given only "foo = 5" ... In Python foo is a Name which is bound to the integer 5. There are other way to describe it, but it all comes down to being symbols representing a concept. (It could have been a randomly generated sequence with no meaning at all too!) Without knowing the context of the discussion, that is all that we can say. However if we were to agree that foo represents a concept that has an unchanging value in the context that it is used, then it is a constant, because we agreed that it is. So it is determined by the meaning we agree (or decide for ourself) to give to the name "foo". So what is the meaning of foo? In general computer discussions foo is ever changing and represents an abstract object to be used and reused to describe a multitude of possibilities. I would call that a variable. ;-) Cheers, Ron -- http://mail.python.org/mailman/listinfo/python-list
Re: Variables
Robert Kern wrote: Richard Blackwood wrote: Robert Kern wrote: If you must, http://en.wikipedia.org/wiki/Variable Fantastic, wikipedia deals precisely with the difference between variables in mathematics versus programming. However, he would never trust a definition from such an "unreputable" source. If you have any other sources I might direct him to...he maintains that the notion of foo being a variable where it's value is known (versus unknown) is illogical. His problem is that he doesn't respect that technical terms can have different meanings in different fields and contexts. No authoritative reference can solve his problem for him. He's being overly pedantic about a field in which *he* is clearly not an authority. You can't convince such people, only ignore them. Unfortunately that's not much of an option for me. We are working on a project together so I am forced to either prove his notion incorrect or I give in to his conception. *throws hands in air* -- http://mail.python.org/mailman/listinfo/python-list
Re: Variables
Richard Blackwood wrote: Robert Kern wrote: If you must, http://en.wikipedia.org/wiki/Variable Fantastic, wikipedia deals precisely with the difference between variables in mathematics versus programming. However, he would never trust a definition from such an "unreputable" source. If you have any other sources I might direct him to...he maintains that the notion of foo being a variable where it's value is known (versus unknown) is illogical. His problem is that he doesn't respect that technical terms can have different meanings in different fields and contexts. No authoritative reference can solve his problem for him. He's being overly pedantic about a field in which *he* is clearly not an authority. You can't convince such people, only ignore them. -- Robert Kern [EMAIL PROTECTED] "In the fields of hell where the grass grows high Are the graves of dreams allowed to die." -- Richard Harter -- http://mail.python.org/mailman/listinfo/python-list
Re: Variables
Bengt Richter wrote: On Sat, 23 Apr 2005 22:45:14 -0400, Richard Blackwood <[EMAIL PROTECTED]> wrote: Robert Kern wrote: Richard Blackwood wrote: To All: Folks, I need your help. I have a friend who claims that if I write: foo = 5 then foo is NOT a variable, necessarily. If you guys can define for me what a variable is and what qualifications you have to back you, I can pass this along to, hopefully, convince him that foo is indeed a variable. None of us can do that unless you tell us what he thinks the word "variable" means. The terminology is a bit fluid. I suspect that your friend applying a somewhat restricted notion of "variable" that coincides with the behavior of variables in some other language. Indeed, this language is math. My friend says that foo is a constant and necessarily not a variable. If I had written foo = raw_input(), he would say that foo is a variable. Which is perfectly fine except that he insists that since programming came from math, the concept of variable is necessarily the identical. This can not be true. For example, I may define foo as being a dictionary, but I can not do this within math because there is no concept of dictionaries within mathematics; yet foo is a variable, a name bound to a value which can change. Maybe he doesn't know that foo = 5 in Python is not an equation as in math, but a Python source language statement to be translated to a step in some processing sequence. Tell him in Python foo is a member of one set and 5 is a member of another, and foo = 5 expresses the step of putting them into correspondence to define a mapping, not declaring them equal. Could I honestly argue this to him? From what basis do I argue that it is not an equation? In any event, he would likely (passionately) disagree considering his notion that programming is an off-shoot of math and thus at the fundamental level has identical concepts and rules. Believe it or not, he used to be a programmer. Back in the day (while I was getting my PhD in philosophy), he was a employed programmer using Cobol, Fortran, and other languages like that. Did his seemingly peculiar definition of variable exist at that time? Even in math notation, ISTM important to distinguish between a finger and what it may for the moment be pointing at. Regards, Bengt Richter -- http://mail.python.org/mailman/listinfo/python-list
Re: Variables
On Sat, 23 Apr 2005 22:45:14 -0400, Richard Blackwood <[EMAIL PROTECTED]> wrote: >Robert Kern wrote: > >> Richard Blackwood wrote: >> >>> To All: >>> >>>Folks, I need your help. I have a friend who claims that if I write: >>> >>> foo = 5 >>> >>> then foo is NOT a variable, necessarily. If you guys can define for >>> me what a variable is and what qualifications you have to back you, I >>> can pass this along to, hopefully, convince him that foo is indeed a >>> variable. >> >> >> None of us can do that unless you tell us what he thinks the word >> "variable" means. The terminology is a bit fluid. I suspect that your >> friend applying a somewhat restricted notion of "variable" that >> coincides with the behavior of variables in some other language. >> >Indeed, this language is math. My friend says that foo is a constant and >necessarily not a variable. If I had written foo = raw_input(), he would >say that foo is a variable. Which is perfectly fine except that he >insists that since programming came from math, the concept of variable >is necessarily the identical. This can not be true. For example, I may >define foo as being a dictionary, but I can not do this within math >because there is no concept of dictionaries within mathematics; yet foo >is a variable, a name bound to a value which can change. Maybe he doesn't know that foo = 5 in Python is not an equation as in math, but a Python source language statement to be translated to a step in some processing sequence. Tell him in Python foo is a member of one set and 5 is a member of another, and foo = 5 expresses the step of putting them into correspondence to define a mapping, not declaring them equal. Even in math notation, ISTM important to distinguish between a finger and what it may for the moment be pointing at. Regards, Bengt Richter -- http://mail.python.org/mailman/listinfo/python-list
Re: Variables
Terry Reedy wrote: "Richard Blackwood" <[EMAIL PROTECTED]> wrote in message news:[EMAIL PROTECTED] Indeed, this language is math. In mathematics, the word 'variable' is generally an undefined meta-term that is *notorious* for having multiple possible meanings and shades of meaning. One mathematician/linguist once claimed to have discerned somewhere around 15 different meanings and shades thereof. What is his/her name? -- http://mail.python.org/mailman/listinfo/python-list
Re: GUI woes
"jeff elkins" <[EMAIL PROTECTED]> wrote in message news:[EMAIL PROTECTED] > under debian sid, I installed (via apt-get) the various wxpython stuff > available.: > > libwxgtk2.4-python > libwxgtk2.5.3-python > python-opengl > python-pythoncard > python2.1-opengl > python2.2-opengl > python2.3-opengl > python2.3-pythoncard > pythoncard > pythoncard-doc > pythoncard-tools > wx2.5-examples > wxpython2.5.3 > wxwin2.4-examples You have a mixture of different versions of wxPython in there. > AttributeError: MyFrame instance has no attribute 'Bind' Bind was introduced in wxPython 2.5. Looks like you are running against thr 2.4 library. Roger -- http://mail.python.org/mailman/listinfo/python-list
Re: Variables
"Richard Blackwood" <[EMAIL PROTECTED]> wrote in message news:[EMAIL PROTECTED] > Indeed, this language is math. In mathematics, the word 'variable' is generally an undefined meta-term that is *notorious* for having multiple possible meanings and shades of meaning. One mathematician/linguist once claimed to have discerned somewhere around 15 different meanings and shades thereof. The context usually makes the particular meaning clear enough, at least to other mathematicians. But the ambiguity sometimes disconcerting to students. > My friend says that foo is a constant and necessarily not a variable. 'constant' is one of the possible meanings of 'variable'. As is "Given that (3*x -2)/5 = 1, what is the value of the variable x". Sometimes, whether a 'variable' actually 'varies' or not, is a matter of viewpoint. We may think of 'varying' as something that happens in time, whereas most math is timeless. In any case, 'foo=5' can be followed, in Python, by 'foo="hopscotch" '. So names (as opposed to objects) do not even have a type. Also, in Python, 'variable' is not a part of the official language description in the way it is for some other programming languages. Terry J. Reedy -- http://mail.python.org/mailman/listinfo/python-list
Re: Variables
Dan Bishop wrote: Richard Blackwood wrote: Steven Bethard wrote: Richard Blackwood wrote: Indeed, this language is math. My friend says that foo is a constant and necessarily not a variable. If I had written foo = raw_input(), he would say that foo is a variable. Then what does he say if you write: foo = 5 foo = 6 ... He says that foo is a constant. At first it was a constant which equaled 5, then it was a constant that equaled 6. He must have a very unusual definition of "constant". I believe he argues that foo existed as two separate constants. He also says that if I write: foo = 6 foo = raw_input() then foo first exists as a constant and then as a variable (because it can then be anything, any value that the user inputs). -- http://mail.python.org/mailman/listinfo/python-list
Re: Variables
Mike Meyer wrote: Richard Blackwood <[EMAIL PROTECTED]> writes: Robert Kern wrote: Richard Blackwood wrote: To All: Folks, I need your help. I have a friend who claims that if I write: foo = 5 then foo is NOT a variable, necessarily. If you guys can define for me what a variable is and what qualifications you have to back you, I can pass this along to, hopefully, convince him that foo is indeed a variable. None of us can do that unless you tell us what he thinks the word "variable" means. The terminology is a bit fluid. I suspect that your friend applying a somewhat restricted notion of "variable" that coincides with the behavior of variables in some other language. Indeed, this language is math. My friend says that foo is a constant and necessarily not a variable. If I had written foo = raw_input(), he would say that foo is a variable. Which is perfectly fine except that he insists that since programming came from math, the concept of variable is necessarily the identical. This can not be true. For example, I may define foo as being a dictionary, but I can not do this within math because there is no concept of dictionaries within mathematics; yet foo is a variable, a name bound to a value which can change. Wrong on two counts. First, new disciplines often redefine words to mean something different than the disciplines they were derived from. Variable is a good example of that. In math, a variable is a placeholder in an (a system of) equation(s), and will have associated with it a (possibly empty) set of values that satisfy the equation(s). Not merely a placeholder, right? A variable in math is a 'placeholder' for a dynamic value, one which can or does change. If one can graph the movement (change) of foo, foo is a variable within that scope. For example: foo = 5 foo = 6 I can graph foo's movement/change. It can thus be considered a variable within mathematics. If I write: foo = 5 I can graph this but it will merely be a static point, a constant. Constants are not variables because they do not change, they do not "vary" in content. In programming, a variable holds a value of some kind. As you point out, the value may be complicated, in that it holds one or more objects. Indeed. In math, if you say "foo = 5", foo is a variable, with a single value (5) that satisfies the equation. In Python, if you say "foo = 5", foo is a variable, that currently references the value 5. He would argue strongly against your notion of variable. In the statement "foo = 5", foo is constant. He would thus argue that foo is a constant and not a variable (regardless of whether you change foo's value in subsequent statements). ... -- http://mail.python.org/mailman/listinfo/python-list
Re: Variables
Richard Blackwood wrote: > Steven Bethard wrote: > > > Richard Blackwood wrote: > > > >> Indeed, this language is math. My friend says that foo is a constant > >> and necessarily not a variable. If I had written foo = raw_input(), > >> he would say that foo is a variable. > > > > > > Then what does he say if you write: > > > > foo = 5 > > foo = 6 ... > He says that foo is a constant. At first it was a constant which equaled > 5, then it was a constant that equaled 6. He must have a very unusual definition of "constant". -- http://mail.python.org/mailman/listinfo/python-list
Re: Variables
Robert Kern wrote: Richard Blackwood wrote: Kent Johnson wrote: Richard Blackwood wrote: To All: Folks, I need your help. I have a friend who claims that if I write: foo = 5 then foo is NOT a variable, necessarily. Indeed, this language is math. My friend says that foo is a constant and necessarily not a variable. Well, we mostly talk Python here, not math. In Python, if you say foo = 5 foo is a name bound to an immutable value. If I had written foo = raw_input(), he would say that foo is a variable. That's funny. foo is still a name bound to an immutable (string) value. foo is no more or less variable than it was with foo = 5. Which is perfectly fine except that he insists that since programming came from math, the concept of variable is necessarily the identical. This can not be true. For example, I may define foo as being a dictionary, but I can not do this within math because there is no concept of dictionaries within mathematics; yet foo is a variable, a name bound to a value which can change. Sounds like you are having a stupid and meaningless argument with your friend. What you call foo won't change what it is. He should learn Python, then he would understand the true zen of foo. That is exactly how I feel about it. Foo is what it is. Variable, name bound to immutable value, etc., what we call it doesn't really change how I program, only how I communicate with other programmers (and mathematicians). Is the notion of variable not a fundamental concept in programming? Surely there must be an unambiguous definition I can relay to him. Why should there be? Different programming languages have different models. In C, a variable corresponds to a memory slot. In Python, it's a just a name that can be bound to an object. If you must, http://en.wikipedia.org/wiki/Variable Fantastic, wikipedia deals precisely with the difference between variables in mathematics versus programming. However, he would never trust a definition from such an "unreputable" source. If you have any other sources I might direct him to...he maintains that the notion of foo being a variable where it's value is known (versus unknown) is illogical. -- http://mail.python.org/mailman/listinfo/python-list
Re: Variables
Richard Blackwood <[EMAIL PROTECTED]> writes: > Robert Kern wrote: >> Richard Blackwood wrote: >>> To All: >>> >>>Folks, I need your help. I have a friend who claims that if I write: >>> >>> foo = 5 >>> >>> then foo is NOT a variable, necessarily. If you guys can define for >>> me what a variable is and what qualifications you have to back you, >>> I can pass this along to, hopefully, convince him that foo is >>> indeed a variable. >> >> None of us can do that unless you tell us what he thinks the word >> "variable" means. The terminology is a bit fluid. I suspect that >> your friend applying a somewhat restricted notion of "variable" that >> coincides with the behavior of variables in some other language. >> > Indeed, this language is math. My friend says that foo is a constant > and necessarily not a variable. If I had written foo = raw_input(), he > would say that foo is a variable. Which is perfectly fine except that > he insists that since programming came from math, the concept of > variable is necessarily the identical. This can not be true. For > example, I may define foo as being a dictionary, but I can not do this > within math because there is no concept of dictionaries within > mathematics; yet foo is a variable, a name bound to a value which can > change. Wrong on two counts. First, new disciplines often redefine words to mean something different than the disciplines they were derived from. Variable is a good example of that. In math, a variable is a placeholder in an (a system of) equation(s), and will have associated with it a (possibly empty) set of values that satisfy the equation(s). In programming, a variable holds a value of some kind. As you point out, the value may be complicated, in that it holds one or more objects. In math, if you say "foo = 5", foo is a variable, with a single value (5) that satisfies the equation. In Python, if you say "foo = 5", foo is a variable, that currently references the value 5. What Python calls a "dictionary" math calls a "mapping", or sometimes a "function" (though that usage is usually reserved for mappings to/from numbers of some kind). A mapping is a relationship between elements of two sets, pairing elements of the first set with elements of the second set. In a Python dictionary, the first set is keys(), and the second set is values(). In both cases, the pairing is unidirectional, as picking an element from the first set (keys) selects a unique element from the second set (values), but picking an element from the second set (values) may pick more than one element from the first set (keys). See http://www.answers.com/topic/function > for more information. Note that lists and tuples are both mappings, though in their case the first set is restricted to the integers. If you check the Python documentation, you'll see these three types (dictionaries, lists and tuples) documented in a section called "Mapping Types". http://www.mired.org/home/mwm/ Independent WWW/Perforce/FreeBSD/Unix consultant, email for more information. -- http://mail.python.org/mailman/listinfo/python-list
Re: help with binary file io, perhaps with generators?
"Marcus Goldfish" <[EMAIL PROTECTED]> wrote in message news:[EMAIL PROTECTED] >I need to write a "fast" file reader in python for binary files structured >as: > > x[0] y[0] z[0] x[1] y[1] z[1] > > where c[k] is the k-th element from sequence c. As mentioned, the > file is binary -- spaces above are just for visualization. Each > element, c[k], is a 16-bit int. You have a sequence of machine-format triples > (ii) how can I handle the 16-bit word aspect of the binary data? that you want to unpack (see struct module) and unzip (your code). > I can assume I know the number of sequences in the file a priori. Then you can pre-allocate x,y,z instead of growing them by appends: x = n*[0]; ... > Files are stored and processed on a > WinXP machine (in case Endian-ness matters). I believe struct module takes care of this. Read its doc. > (i) should I use generators for iterating over the file? If you will only ever unpack when you also unzip to separate lists, then you might put the unpack code in the inner loop of the unzip method. If you think that you might someday directly process the file as a sequence of scaler triples without creating intermediate x,y,z lists, then you should factor out the file read/unpack as you are thinking. > (iii) ultimately, the data will need to be processed in chunks of > M-values at a time... I assume this means I need some > form of buffered io wrapper, but I'm not sure where to start > with this. I presume this means M triplets or 3*N values. In any case, Python is ahead of you ;-). >>>help(file.read) read([size]) -> read at most size bytes, returned as a string. If the size argument is negative or omitted, read until EOF is reached. Terry J. Reedy -- http://mail.python.org/mailman/listinfo/python-list
Re: Variables
Richard Blackwood wrote: Kent Johnson wrote: Richard Blackwood wrote: To All: Folks, I need your help. I have a friend who claims that if I write: foo = 5 then foo is NOT a variable, necessarily. Indeed, this language is math. My friend says that foo is a constant and necessarily not a variable. Well, we mostly talk Python here, not math. In Python, if you say foo = 5 foo is a name bound to an immutable value. If I had written foo = raw_input(), he would say that foo is a variable. That's funny. foo is still a name bound to an immutable (string) value. foo is no more or less variable than it was with foo = 5. Which is perfectly fine except that he insists that since programming came from math, the concept of variable is necessarily the identical. This can not be true. For example, I may define foo as being a dictionary, but I can not do this within math because there is no concept of dictionaries within mathematics; yet foo is a variable, a name bound to a value which can change. Sounds like you are having a stupid and meaningless argument with your friend. What you call foo won't change what it is. He should learn Python, then he would understand the true zen of foo. That is exactly how I feel about it. Foo is what it is. Variable, name bound to immutable value, etc., what we call it doesn't really change how I program, only how I communicate with other programmers (and mathematicians). Is the notion of variable not a fundamental concept in programming? Surely there must be an unambiguous definition I can relay to him. Why should there be? Different programming languages have different models. In C, a variable corresponds to a memory slot. In Python, it's a just a name that can be bound to an object. If you must, http://en.wikipedia.org/wiki/Variable -- Robert Kern [EMAIL PROTECTED] "In the fields of hell where the grass grows high Are the graves of dreams allowed to die." -- Richard Harter -- http://mail.python.org/mailman/listinfo/python-list
Re: Python or PHP?
John Bokma <[EMAIL PROTECTED]> writes: > Mike Meyer wrote: > >> John Bokma <[EMAIL PROTECTED]> writes: >> >>> Mike Meyer wrote: >>> "Simon John" <[EMAIL PROTECTED]> writes: > I still love Perl, it's a bit of an art form, as "there's more than > one way to do it", whereas Python usually only allows one way to do > it, which may or may not be a better mantra The Python mantra leads to 1) less programmer overhead, and 2) > faster improvements in the language. To be a Perl expert, you have to know which of the many ways to do various things is the fasted under what conditions. >>> >>> Why? >> >> One of the stated conditions for more than one Perl position I've >> looked at. > > That's weird, since some can differ between versions of Perl like for > example a map in a void context. And I am sure Python has now and then > improvements which make one operation suddenly 10% faster in a new > version. The things is - it doesn't matter nearly as much in Python. Since there's only one obvious way to do most simple things, that's the one that most programmers will choose, and that's the one the developers will worry about making faster. > So it tells you a lot about the people providing the position ;-) Yeah - they expect their people to be on top of such things. I've never run across a Python position where knowing which of several ways was faster was an important criterion - because there usually aren't several ways. Having only one obvious way >>> I doubt that too ;-) >> Try programming in older Python for a while. You'll quit doubting it. > Again I doubt that. I doubt that if I give 100 old Python programmers a > certain computer science problem I will see 100 exactly the same > solutions, which when benchmarked run equally fast. Depends on the problem. If it's one of the things for which Python has an obvious solution (sort a list; split a string on whitespace; pull select list elements based on a criteria of some kind; search a file for lines with a given word in them; etc.) you'd get back the same answer from almost all of them. As I've said a number of times, this has changed lately as new features have been added without removing their older counterparts. to do things means developers only have to worry about impact on that way when making improvements, which will speed them up. >>> Yeah, Perl programmers are extremely slow ;-) >> Nah, they aren't slow. They just have to worry about more things than >> the Python developers. > Do you have references to this? I would love to see if indeed 100 Python > programmers do implement, say 5 CS tasks faster compared to 100 Perl > programmers, on average. I'm talking about the people developing the language, not the ones developing in the language. And this is just my impression from watching the developers lists. >> If speed >> is an issue, you should probably pick a different >> algorithm. Well-written Python programs use the C-coded parts of >> Python for the time-critical part of the code. > Why are those time critical parts not written in Python ;-) Because then they'd be slower. A good scripting environment has lots of operations available that are coded at a low level. Since this code is usually hand-tuned and optimized over time (like the dictionary lookup or string operations in Python, or regular expressions in Perl - I'm not sure about the RE library in Python), it may well be faster than what you'd write in the low level language if you did it yourself. >>> Use the one that is the easiest to read and understand by yourself. >>> That's how I program Perl, and that's how I am going to program > Python. >> The thing is, in Python there usually is one obvious way to do >> things. That's changed in recent years as improvements have been added >> without dropping the features they replaced so as not to break old >> programs. > I know to little about Python, especially about old Python, to have an > idea of what you mean. I only saw, quite recently, someones solution to > a problem that used 30 lines of Python, and I am sure I could have > written it in 3-4. And I doubt that's because he was using, or I was > thinking in, new Python > :-D. Just because there's only one obvious way to do things doesn't mean it's obvious to everyone. Witness the recent spate of people asking for "goto". >>> An overloaded toolbox doesn't mean that if you have to hang a > painting >>> on the wall that you have to think for 6 hours which tool you should >>> use. You just take the one that does the job in a way you feel >>> comfortable with. I know that the Perl mantra is often misunderstood, >>> but in my experience only by people who have very little experience > with >>> the language. >> The problem with using "the way you feel comfortable with" is that it >> may not be comfortable for the maintainer - even if that's you six >> months from now. > After 5 years one gets comf
Re: Variables
Kent Johnson wrote: Richard Blackwood wrote: To All: Folks, I need your help. I have a friend who claims that if I write: foo = 5 then foo is NOT a variable, necessarily. Indeed, this language is math. My friend says that foo is a constant and necessarily not a variable. Well, we mostly talk Python here, not math. In Python, if you say foo = 5 foo is a name bound to an immutable value. If I had written foo = raw_input(), he would say that foo is a variable. That's funny. foo is still a name bound to an immutable (string) value. foo is no more or less variable than it was with foo = 5. Which is perfectly fine except that he insists that since programming came from math, the concept of variable is necessarily the identical. This can not be true. For example, I may define foo as being a dictionary, but I can not do this within math because there is no concept of dictionaries within mathematics; yet foo is a variable, a name bound to a value which can change. Sounds like you are having a stupid and meaningless argument with your friend. What you call foo won't change what it is. He should learn Python, then he would understand the true zen of foo. That is exactly how I feel about it. Foo is what it is. Variable, name bound to immutable value, etc., what we call it doesn't really change how I program, only how I communicate with other programmers (and mathematicians). Is the notion of variable not a fundamental concept in programming? Surely there must be an unambiguous definition I can relay to him. -- http://mail.python.org/mailman/listinfo/python-list
Re: Variables
Richard Blackwood wrote: Indeed, this language is math. My friend says that foo is a constant and necessarily not a variable. If I had written foo = raw_input(), he would say that foo is a variable. Which is perfectly fine except that he insists that since programming came from math, the concept of variable is necessarily the identical. This can not be true. For example, I may define foo as being a dictionary, but I can not do this within math because there is no concept of dictionaries within mathematics; yet foo is a variable, a name bound to a value which can change. Your friend needs to learn, and very quickly if he persists in inflicting his erroneous pedantry on other people, that technical terms have different meanings in different fields, even if one can imagine that one "came from" the other. Hell, even in the same field, it can mean different things. Ask him what "domain" means in mathematics. And check his answer[1]. While one could argue that using the term "variable" for Python names is incorrect for good programming reasons, your friend's reasoning is ridiculous. [1] http://mathworld.wolfram.com/Domain.html -- Robert Kern [EMAIL PROTECTED] "In the fields of hell where the grass grows high Are the graves of dreams allowed to die." -- Richard Harter -- http://mail.python.org/mailman/listinfo/python-list
Re: Bounding box on clusters in a 2D list
On 23 Apr 2005 13:17:55 -0700, "[EMAIL PROTECTED]" <[EMAIL PROTECTED]> wrote: >If I have > >ex: x = [[1,1,1,0,0,0,0,0,0,0,0,1,1,1,1,0,0,0], > [1,1,1,0,1,1,0,0,0,0,0,1,1,1,1,0,0,0], > [1,1,1,0,1,1,1,0,1,1,0,1,1,1,0,0,0,0], > [0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0]] >what I want is a boundingbox over the region where we find clusters of >1's.So for instance in the above list first 3 roes and colums have 1's >so the area of that box is 3x3 >so my final array should have an array of approx areas of clusters of >1's like >area = [ 9,4 ] Where does the 4 come from? >Hope I am clear with my question. > Not quite clear on if "clusters" have to be rectangular and fill their bounding boxes or whether [[0, 0, 0, 0, 0], +-+ [0,|1, 1,|0, 0], | | [0,|0, 1,|0, 0], +-+ [0, 0, 0, 0, 0]] is a cluster with three 1's. Or indeed whether "bounding boxes" have to be rectangular. I.e., what about diagonal clusters? ,__, [[0, 0,|1,|0, 0], _/ _/ ,__, [0,/1,/0, 0,|1], _/ _/_/ / [1,/0, 0,/1,/0], _/ / [0, 0,/1,/0, 0]] Or should that be +-+ [[|0, 0, 1, 0, 0|], | | [|0, 1, 0, 0, 1|], | | [|1, 0, 0, 1, 0|], | | [|0, 0, 1, 0, 0|]] +-+ since two 3x3 squares around the length-3 diagonals would overlap. Regards, Bengt Richter -- http://mail.python.org/mailman/listinfo/python-list
Re: Variables
Steven Bethard wrote: Richard Blackwood wrote: Indeed, this language is math. My friend says that foo is a constant and necessarily not a variable. If I had written foo = raw_input(), he would say that foo is a variable. Then what does he say if you write: foo = 5 foo = 6 ? STeVe He says that foo is a constant. At first it was a constant which equaled 5, then it was a constant that equaled 6. -- http://mail.python.org/mailman/listinfo/python-list
Re: Variables
Richard Blackwood wrote: To All: Folks, I need your help. I have a friend who claims that if I write: foo = 5 then foo is NOT a variable, necessarily. Indeed, this language is math. My friend says that foo is a constant and necessarily not a variable. Well, we mostly talk Python here, not math. In Python, if you say foo = 5 foo is a name bound to an immutable value. If I had written foo = raw_input(), he would say that foo is a variable. That's funny. foo is still a name bound to an immutable (string) value. foo is no more or less variable than it was with foo = 5. Which is perfectly fine except that he insists that since programming came from math, the concept of variable is necessarily the identical. This can not be true. For example, I may define foo as being a dictionary, but I can not do this within math because there is no concept of dictionaries within mathematics; yet foo is a variable, a name bound to a value which can change. Sounds like you are having a stupid and meaningless argument with your friend. What you call foo won't change what it is. He should learn Python, then he would understand the true zen of foo. Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: Variables
Richard Blackwood wrote: Indeed, this language is math. My friend says that foo is a constant and necessarily not a variable. If I had written foo = raw_input(), he would say that foo is a variable. Then what does he say if you write: foo = 5 foo = 6 ? STeVe -- http://mail.python.org/mailman/listinfo/python-list
Re: Unicode problems, yet again
On Sun, 24 Apr 2005 03:15:02 +0200, Ivan Voras
<[EMAIL PROTECTED]> wrote:
>I have a string fetched from database, in iso8859-2, with 8bit
>characters,
"8bit characters"?? Maybe you did once, or you thought you did, but
what you have now is a Unicode string, and socket.write() is expecting
an ordinary string.
> and I'm trying to send it over the network, via a socket:
>
> File "E:\Python24\lib\socket.py", line 249, in write
> data = str(data) # XXX Should really reject non-string non-buffers
>UnicodeEncodeError: 'ascii' codec can't encode character u'\u0161' in
>position 123: ordinal not in range(128)
Like it says, you have passed it a *UNICODE* string that has u'\u0161'
(the small s with caron) at position 123.
>
>The other end knows it should expect this encoding, so how to send it?
>
If the other end wants an encoding, then you should *encode* it, like
this:
>>> us = u'\u0161'
>>> s = us.encode('iso8859_2')
>>> s
'\xb9'
>>> str(us)
Traceback (most recent call last):
File "", line 1, in ?
UnicodeEncodeError: 'ascii' codec can't encode character u'\u0161' in
position 0: ordinal not in range(128)
>>> str(s)
'\xb9'
>>> # looks like socket.write() might be happier with this.
>(Does anyone else feel that python's unicode handling is, well...
>suboptimal at least?)
Your posting gives no evidence for such a conclusion.
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Re: Variables
Robert Kern wrote: Richard Blackwood wrote: To All: Folks, I need your help. I have a friend who claims that if I write: foo = 5 then foo is NOT a variable, necessarily. If you guys can define for me what a variable is and what qualifications you have to back you, I can pass this along to, hopefully, convince him that foo is indeed a variable. None of us can do that unless you tell us what he thinks the word "variable" means. The terminology is a bit fluid. I suspect that your friend applying a somewhat restricted notion of "variable" that coincides with the behavior of variables in some other language. Indeed, this language is math. My friend says that foo is a constant and necessarily not a variable. If I had written foo = raw_input(), he would say that foo is a variable. Which is perfectly fine except that he insists that since programming came from math, the concept of variable is necessarily the identical. This can not be true. For example, I may define foo as being a dictionary, but I can not do this within math because there is no concept of dictionaries within mathematics; yet foo is a variable, a name bound to a value which can change. -- http://mail.python.org/mailman/listinfo/python-list
Re: Variables
Richard Blackwood wrote: To All: Folks, I need your help. I have a friend who claims that if I write: foo = 5 then foo is NOT a variable, necessarily. If you guys can define for me what a variable is and what qualifications you have to back you, I can pass this along to, hopefully, convince him that foo is indeed a variable. None of us can do that unless you tell us what he thinks the word "variable" means. The terminology is a bit fluid. I suspect that your friend applying a somewhat restricted notion of "variable" that coincides with the behavior of variables in some other language. -- Robert Kern [EMAIL PROTECTED] "In the fields of hell where the grass grows high Are the graves of dreams allowed to die." -- Richard Harter -- http://mail.python.org/mailman/listinfo/python-list
Re: Variables
Indeed, but is it not a variable? Is a variable in programming not merely a name associated with a value (which can changed over the course of code execution)? James Stroud wrote: I think, strictly speaking, foo would be a "name" in python. foo Traceback (most recent call last): File "", line 1, in ? NameError: name 'foo' is not defined On Saturday 23 April 2005 07:20 pm, so sayeth Richard Blackwood: To All: Folks, I need your help. I have a friend who claims that if I write: foo = 5 then foo is NOT a variable, necessarily. If you guys can define for me what a variable is and what qualifications you have to back you, I can pass this along to, hopefully, convince him that foo is indeed a variable. Thanks all! Richard B. -- http://mail.python.org/mailman/listinfo/python-list
Re: Variables
I think, strictly speaking, foo would be a "name" in python. >>> foo Traceback (most recent call last): File "", line 1, in ? NameError: name 'foo' is not defined On Saturday 23 April 2005 07:20 pm, so sayeth Richard Blackwood: > To All: > > Folks, I need your help. I have a friend who claims that if I write: > > foo = 5 > > then foo is NOT a variable, necessarily. If you guys can define for me > what a variable is and what qualifications you have to back you, I can > pass this along to, hopefully, convince him that foo is indeed a variable. > > Thanks all! > > Richard B. -- James Stroud UCLA-DOE Institute for Genomics and Proteomics Box 951570 Los Angeles, CA 90095 http://www.jamesstroud.com/ -- http://mail.python.org/mailman/listinfo/python-list
Variables
To All: Folks, I need your help. I have a friend who claims that if I write: foo = 5 then foo is NOT a variable, necessarily. If you guys can define for me what a variable is and what qualifications you have to back you, I can pass this along to, hopefully, convince him that foo is indeed a variable. Thanks all! Richard B. -- http://mail.python.org/mailman/listinfo/python-list
Re: Unicode problems, yet again
Ivan Voras wrote:
I have a string fetched from database, in iso8859-2, with 8bit
characters, and I'm trying to send it over the network, via a socket:
File "E:\Python24\lib\socket.py", line 249, in write
data = str(data) # XXX Should really reject non-string non-buffers
UnicodeEncodeError: 'ascii' codec can't encode character u'\u0161' in
position 123: ordinal not in range(128)
The other end knows it should expect this encoding, so how to send it?
I think maybe the string from the database is a unicode string, not 8-bit. What happens if you write
data.encode('iso8859-2') ?
(Does anyone else feel that python's unicode handling is, well...
suboptimal at least?)
It can be confusing and surprising, yes. Suboptimal...well, I wouldn't want to say that I could do
better...
Kent
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help with binary file io, perhaps with generators?
I need to write a "fast" file reader in python for binary files structured as: … x[0] y[0] z[0] x[1] y[1] z[1] … where c[k] is the k-th element from sequence c. As mentioned, the file is binary -- spaces above are just for visualization. Each element, c[k], is a 16-bit int. I can assume I know the number of sequences in the file a priori. Files are stored and processed on a WinXP machine (in case Endian-ness matters). I'm looking for suggestions on how to tackle this problem, and how to design my reader class. Or if anyone has sample code: that would be appreciated, too. Some questions I have to start with: (i) should I use generators for iterating over the file? (ii) how can I handle the 16-bit word aspect of the binary data? (iii) ultimately, the data will need to be processed in chunks of M-values at a time... I assume this means I need some form of buffered io wrapper, but I'm not sure where to start with this. Thanks! Marcus Ps -- this seems like a general stream processing problem… if anyone can recommend good refs (web) on stream processing -- http://mail.python.org/mailman/listinfo/python-list
Re: Unicode problems, yet again
On Sun, 24 Apr 2005 03:15:02 +0200, Ivan Voras <[EMAIL PROTECTED]> wrote:
I have a string fetched from database, in iso8859-2, with 8bit characters,
and I'm trying to send it over the network, via a socket:
You don't have a string fetched from a database, in iso-8859-2, alas.
That is the root of the problem you're having. What you have is a unicode
string.
It's easy to go from this to what you want (iso-8859-2 encoded string),
fortunately. Just call unicodeStr.encode('iso-8859-2') and write the result
over the socket.
(Does anyone else feel that python's unicode handling is, well... suboptimal
at least?)
Hmm. Not really. The only problem I've found with it is misguided attempt to
"do the right thing" by implicitly encoding unicode strings, and this isn't so
much of a problem once you figure things out, because you can always do things explicitly
and avoid invoking the implicit behavior.
Jp
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Re: Python or PHP?
Peter Ammon wrote: I'm bewildered why you haven't mentioned magic quotes. A one line change to the configuration file can render your PHP site almost entirely immune to SQL injection attacks. PHP's magic quotes is one of the most poorly-designed features I can think of. Instead of magically escaping only strings which will actually be passed to a database (like Python's DB-API does), it escapes every string that comes from the user, meaning that strings which will be sent back to the user have to be manually unescaped. Even worse, since it can be turned on and off, code which is designed for a magic_quotes=on environment will become seriously vulnerable when moved to an environment with magic_quotes on. Security-related features should never be toggleable! -- http://mail.python.org/mailman/listinfo/python-list
Re: GUI woes
The Great jeff elkins uttered these words on 4/23/2005 5:45 PM: test.py crashes with the error below. Any clues? === Running test.py: Traceback (most recent call last): File "./test.py", line 87, in ? app = MyApp(0) # Create an instance of the application class File "/usr/lib/python2.3/site-packages/wxPython/wx.py", line 1951, in __init__ _wxStart(self.OnInit) File "./test.py", line 76, in OnInit frame = MyFrame(None, -1, "This is a test") File "./test.py", line 26, in __init__ self.Bind(wx.EVT_SIZE, self.OnSize) AttributeError: MyFrame instance has no attribute 'Bind' Jeff - Could you please post your code? From what you have posted it looks like your MyFrame class does not inherit from wx.Frame. Your class should be defined like this: class MyFrame(wx.Frame): def __init__(self, parent, id, title, pos, size, style): wx.Frame.__init__(self, parent, id, title, pos, size, style) self.Bind(wx.EVT_SIZE, self.OnSize) self.Show(True) Thanks, -Kartic -- http://mail.python.org/mailman/listinfo/python-list
GUI woes
Howdy, This may not belong here, if so apologies... I'm a python newbie, but have completed a console app that I'd like to run under X. Reading recent postings here, wxpython seemed a reasonable choice so under debian sid, I installed (via apt-get) the various wxpython stuff available.: libwxgtk2.4-python libwxgtk2.5.3-python python-opengl python-pythoncard python2.1-opengl python2.2-opengl python2.3-opengl python2.3-pythoncard pythoncard pythoncard-doc pythoncard-tools wx2.5-examples wxpython2.5.3 wxwin2.4-examples test.py crashes with the error below. Any clues? === Running test.py: Traceback (most recent call last): File "./test.py", line 87, in ? app = MyApp(0) # Create an instance of the application class File "/usr/lib/python2.3/site-packages/wxPython/wx.py", line 1951, in __init__ _wxStart(self.OnInit) File "./test.py", line 76, in OnInit frame = MyFrame(None, -1, "This is a test") File "./test.py", line 26, in __init__ self.Bind(wx.EVT_SIZE, self.OnSize) AttributeError: MyFrame instance has no attribute 'Bind' -- http://mail.python.org/mailman/listinfo/python-list
Re: Python or PHP?
John Bokma <[EMAIL PROTECTED]> writes: > Mike Meyer wrote: > >> "Simon John" <[EMAIL PROTECTED]> writes: >> >>> I still love Perl, it's a bit of an art form, as "there's more than >>> one way to do it", whereas Python usually only allows one way to do >>> it, which may or may not be a better mantra >> >> The Python mantra leads to 1) less programmer overhead, and 2) faster >> improvements in the language. >> >> To be a Perl expert, you have to know which of the many ways to do >> various things is the fasted under what conditions. > > Why? One of the stated conditions for more than one Perl position I've looked at. >> Python programmers >> seldom have to worry about that - there's usually only one [obvious] >> way to do things, so you just do it that way. > > I doubt that :-D. I have never seen a programming language that forced > me in such a way :-D. I'd say you haven't seen a lot of languages - including Python. COBOL, Eiffel, Rexx, Scheme, APL and a few others come to mind as "there's usually only one way to do things". Python is one of them. As a programmer, I find this very *freeing*. I can quite worrying about implementation minutia - just do things the obvious way - and worry instead about the "big picture" >> Having only one obvious way > I doubt that too ;-) Try programming in older Python for a while. You'll quit doubting it. >> to do things means developers only have to >> worry about impact on that way when making improvements, which will >> speed them up. > Yeah, Perl programmers are extremely slow ;-) Nah, they aren't slow. They just have to worry about more things than the Python developers. >> The problem these days is that there are now multiple ways to do a >> variety of things, because we have the "new, pythonic" way and the >> "old, backwards-compatible way". So it's no longer clear which is the >> fastest - > In most cases, why worry? If speed is an issue you should probably have > picked a different programming language in the first place (for that > part of the code). You apparently haven't been programming in Python very long. If speed is an issue, you should probably pick a different algorithm. Well-written Python programs use the C-coded parts of Python for the time-critical part of the code. >> and in the case of generators versus list comprehensions, >> it's not clear which you should be using. To bad. > Use the one that is the easiest to read and understand by yourself. > That's how I program Perl, and that's how I am going to program Python. The thing is, in Python there usually is one obvious way to do things. That's changed in recent years as improvements have been added without dropping the features they replaced so as not to break old programs. > An overloaded toolbox doesn't mean that if you have to hang a painting > on the wall that you have to think for 6 hours which tool you should > use. You just take the one that does the job in a way you feel > comfortable with. I know that the Perl mantra is often misunderstood, > but in my experience only by people who have very little experience with > the language. The problem with using "the way you feel comfortable with" is that it may not be comfortable for the maintainer - even if that's you six months from now. My Perl evolved from very shell script like (lots of backticks and passing around the full text of files) to one more C-like as I used the language. That change was largely driven by performance concerns as my understanding of the language grew. http://www.mired.org/home/mwm/ Independent WWW/Perforce/FreeBSD/Unix consultant, email for more information. -- http://mail.python.org/mailman/listinfo/python-list
Unicode problems, yet again
I have a string fetched from database, in iso8859-2, with 8bit characters, and I'm trying to send it over the network, via a socket: File "E:\Python24\lib\socket.py", line 249, in write data = str(data) # XXX Should really reject non-string non-buffers UnicodeEncodeError: 'ascii' codec can't encode character u'\u0161' in position 123: ordinal not in range(128) The other end knows it should expect this encoding, so how to send it? (Does anyone else feel that python's unicode handling is, well... suboptimal at least?) -- http://mail.python.org/mailman/listinfo/python-list
Re: Bounding box on clusters in a 2D list
I hope this is what you need, sometimes understanding the question is one of the hardest parts :-) If you can use a graph data structure, you can create a graph, and then you can find the lenght of all its connected components (indentations reduced to 2 spaces): . def mat2graph(g, m, good=None, w=1): . "Function docs..." . g.clear() . if m and isinstance(m, (list, tuple)): . if good != None: . m = [[good(e) for e in row] for row in m] . maxy = len(m)-1 . maxx = len(m[0])-1 . add = g.addBiArc . for y, row in enumerate(m): . for x, e in enumerate(row): . if e: . g.addNode((x,y)) # Necessary for isolated nodes. . if x>0 and m[y][x-1]: add( (x,y), (x-1,y), w=w) . if x0 and m[y-1][x]: add( (x,y), (x,y-1), w=w) . if yhttp://www.student.kuleuven.ac.be/~m0216922/CG/floodfill.html"""; . if c>=0 and c=0 and rhttp://www.codeproject.com/gdi/QuickFill.asp I think Python PIL doesn't support flood fills, and I think doing it with Numarray is slower, and it's useful only to reduce the used memory. This connected program is slow and raw, and it uses recursivity a lot, so it can crash the interpreter. You can use a data structure to implement the stack yourself, to speed this program up. But for small matrices I think this connected is enough ^_^ Bear hugs, Bearophile -- http://mail.python.org/mailman/listinfo/python-list
Re: Python or PHP?
Leif K-Brooks wrote:
John Bokma wrote:
my $sort = $cgi->param( "sort" );
my $query = "SELECT * FROM table WHERE id=? ORDER BY $sort";
And the equivalent Python code:
cursor.execute('SELECT * FROM table WHERE id=%%s ORDER BY %s' % sort,
[some_id])
You're right, of course, about being *able* to write code with SQL
injection vulnerabilities in Python. But it's not even close to being as
easy as in PHP.
I'm bewildered why you haven't mentioned magic quotes. A one line
change to the configuration file can render your PHP site almost
entirely immune to SQL injection attacks.
-Peter
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Pull out a splinter to reply.
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Re: Using Ming on Windows
Colin J. Williams wrote: Jack Diederich wrote: On Sat, Apr 23, 2005 at 05:13:29PM -0300, Andr? Roberge wrote: I tried to install Ming (http://sourceforge.net/projects/ming/) on Windows to use with Python *but* I can't [/don't know how to] use "make" to install it. I installed MinGW on a Windows XP with no trouble. One needs to install MSYS, as well as MinGW, since some modules (eg. make) are only available in MSYS. Currently, I am trying to build a package from source and have some unresolved problems. Earlier I had tried to use the Borland commandline, without success. Colin W. MinGW is a minimalistic Gnu for Windows. Ming is a Flash/swf library. A. -- http://mail.python.org/mailman/listinfo/python-list
Re: Using Ming on Windows
Jack Diederich wrote: On Sat, Apr 23, 2005 at 05:13:29PM -0300, Andr? Roberge wrote: I tried to install Ming (http://sourceforge.net/projects/ming/) on Windows to use with Python *but* I can't [/don't know how to] use "make" to install it. Does anyone know where I could find a ready-made compiled version for Windows to just "put in" my site-packages directory. Any help would be appreciated. Ming seems to be abandoded/unsupported. Use groups.google.com to find some hints on how to install it. I've done it on linux, but never tried on windows (why would I?) and replied with some suggestions last time it came up on c.l.py -jackdied I installed MinGW on a Windows XP with no trouble. One needs to install MSYS, as well as MinGW, since some modules (eg. make) are only available in MSYS. Currently, I am trying to build a package from source and have some unresolved problems. Earlier I had tried to use the Borland commandline, without success. Colin W. -- http://mail.python.org/mailman/listinfo/python-list
Re: Handling lists
[EMAIL PROTECTED] wrote: ... list = [[10,11,12,13,14,78,79,80,81,300,301,308]] how do I convert it so that I arrange them into bins . so If i hvae a set of consecutive numbers i would like to represent them as a range in the list with max and min val of the range alone. I shd get something like list = [[10,14],[78,81],[300,308]] Mage: Maybe: list = [10,11,12,13,14,78,79,80,81,300,301,308] new_list = [] start = 0 for i in range(1,len(list) + 1): if i == len(list) or list[i] - list[i-1] <> 1: new_list.append([list[start],list[i-1]]) start = i print new_list [EMAIL PROTECTED] wrote: yes that makes sense.But the problem I am facing is if list= [300,301,303,305] I want to consider it as one cluster and include the range as [300,305] so this is where I am missing the ranges. so If the list has l = [300,301,302,308,401,402,403,408] i want to include it as [[300,308],[401,408]]. Mage's solution meets the requirements that you initially stated of treating *consecutive* numbers as a group. Now you also want to consider [300,301,303,305] as a cluster. You need to specify your desired clustering rule, or alternatively specify ho many bins you want to create, but as an example, here is a naive approach, that could be adapted easily to other clustering rules and (a bit less easily) to target a certain number of bins def lstcluster(lst): # Separate neighbors that differ by more than the mean difference lst.sort() diffs = [(b-a, (a, b)) for a, b in zip(lst,lst[1:])] mean_diff = sum(diff[0] for diff in diffs)/len(diffs) breaks = [breaks for diff, breaks in diffs if diff > mean_diff] groups = [lst[0]] + [i for x in breaks for i in x] + [lst[-1]] igroups = iter(groups) # Pairing mechanism due to James Stroud return [[i, igroups.next()] for i in igroups] Note this is quite inefficient due to creating several intermediate lists. But it's not worth optimizing yet, since I'm only guessing at your actual requirement. lst0 = [10,11,12,13,14,78,79,80,81,300,301,308] lst1 = [10,12,16,24,26,27,54,55,80,100, 105] lst3 = [1,5,100,1000,1005,1009,1, 10010,10019] >>> lst0 = [10,11,12,13,14,78,79,80,81,300,301,308] >>> lst1 = [10,12,16,24,26,27,54,55,80,100, 105] >>> lst2 = [1,5,100,1000,1005,1009,1, 10010,10019] >>> lstcluster(lst0) [[10, 14], [78, 81], [300, 308]] >>> lstcluster(lst1) [[10, 27], [54, 55], [80, 80], [100, 105]] >>> lstcluster(lst2) [[1, 1009], [1, 10019]] >>> Michael -- http://mail.python.org/mailman/listinfo/python-list
Re: Python or PHP?
Leif K-Brooks skrev:
> But Python's DB-API (the standard way to connect to an SQL database
> from Python) makes escaping SQL strings automatic. You can do this:
>
> cursor.execute('UPDATE foo SET bar=%s WHERE id=%s', ["foo'bar", 123])
So. I've been writing SQL queries in Python like this, using PostgreSQL
and psycopg:
cursor.execute("select * from foo where bar=%s" % baz)
Is that wrong, and how should I have been supposed to know that this is
bad syntax? No doc I have seen actually has told me so.
--
Leif Biberg Kristensen
http://solumslekt.org/
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Re: Python or PHP?
John Bokma wrote:
my $sort = $cgi->param( "sort" );
my $query = "SELECT * FROM table WHERE id=? ORDER BY $sort";
And the equivalent Python code:
cursor.execute('SELECT * FROM table WHERE id=%%s ORDER BY %s' % sort,
[some_id])
You're right, of course, about being *able* to write code with SQL
injection vulnerabilities in Python. But it's not even close to being as
easy as in PHP.
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Re: PDF Printing support from Python
On 2005-04-23, Mike Meyer <[EMAIL PROTECTED]> wrote:
>>> No, you don't. My print system does that, and I don't have
>>> acrobat installed. I have ghostscript installed, which
>>> includes pdf2ps - which handles this particular translation.
>>>
>> Okay, so you've converted one page layout language
>> (PDF) to another (PS)... To actually print it you still need a
>> RIP. A PostScript laser printer has the RIP built-in, but
>> consumer level Windows printers do not have a PostScript RIP
>> -- and some printers don't even have their own specific RIP
>> built-in ("winprinters" put the RIP into the software driver
>> that runs on the Windows machine, rather than sending drawing
>> commands to the printer for rendering).
>
> RIP? That term is to generic for google to be much use.
Raster Image Processor. It renders postscript into a raster
image at the proper image.
--
Grant Edwards grante Yow! If this is the DATING
at GAME I want to know your
visi.comFAVORITE PLANET! Do I get
th' MICROWAVE MOPED?
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Re: Python or PHP?
John Bokma wrote: Not. Perl and Java use similar methods where one can specify place holders, and pass on the data unescaped. But still injection is possible. How? -- http://mail.python.org/mailman/listinfo/python-list
Re: PDF Printing support from Python
Dennis Lee Bieber <[EMAIL PROTECTED]> writes:
> On Fri, 22 Apr 2005 17:41:22 -0500, Mike Meyer <[EMAIL PROTECTED]> declaimed
> the following in comp.lang.python:
>
>> No, you don't. My print system does that, and I don't have acrobat
>> installed. I have ghostscript installed, which includes pdf2ps - which
>> handles this particular translation.
>>
> Okay, so you've converted one page layout language (PDF) to
> another (PS)... To actually print it you still need a RIP. A PostScript
> laser printer has the RIP built-in, but consumer level Windows printers
> do not have a PostScript RIP -- and some printers don't even have their
> own specific RIP built-in ("winprinters" put the RIP into the software
> driver that runs on the Windows machine, rather than sending drawing
> commands to the printer for rendering).
RIP? That term is to generic for google to be much use.
If you're saying you need a tool to convert from PDF to whatever the
printer understands, you're right. You can't avoid that. On Unix, PS
is used as the "universal" printer language. Unix vendors selling
printers sold PS printers 20 years ago. That's when apsfilter showed
up on the scene, automatically converting everything to PS to send it
to the printer. (These days, magicfilter is a much better tool than
apsfilter, though it's harder to install). That's why a "competent"
printer installation these days will include ghostscript (or something
equivalent) to drive the printer, and why my primary printer speaks
PostScript.
I disagree with your description of WinPrinters. Those are printers to
stupid to handle flat ASCII, so your computer has to convert flat
ASCII files to postscript or some other graphics format before you can
print them. (This is where magicfilter beats apsfilter - apsfilter
converts ASCII to PS to graphics images, whereas magicfilter can pass
the text straight through. This has caused apsfilter to fail on some
systems where magicfilter would work like a charm). Such printers
typically only come with drivers for Windows, and are completely
useless - unable to even print flat ASCII text - on other systems,
hence the moniker "WinPrinters". Non-winprinters can be used to print
flat ASCII without a driver of any kind. GhostScript now includes
graphics drivers for several winprinters.
The only way to have Python render PDF (or PS, or JPEG, or any other
graphics format) without a "driver" of some kind is to write the
driver in Python. That's a pretty silly thing to want to do. For one
thing, the performance will probably suck. For another, there are lots
of drivers already written that you can use.
The only thing better than writing it in Python is finding that
someone else has already written it.
http://www.mired.org/home/mwm/
Independent WWW/Perforce/FreeBSD/Unix consultant, email for more information.
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Re: Python or PHP?
"Simon John" <[EMAIL PROTECTED]> writes: > I still love Perl, it's a bit of an art form, as "there's more than one > way to do it", whereas Python usually only allows one way to do it, > which may or may not be a better mantra The Python mantra leads to 1) less programmer overhead, and 2) faster improvements in the language. To be a Perl expert, you have to know which of the many ways to do various things is the fasted under what conditions. Python programmers seldom have to worry about that - there's usually only one [obvious] way to do things, so you just do it that way. Having only one obvious way to do things means developers only have to worry about impact on that way when making improvements, which will speed them up. The problem these days is that there are now multiple ways to do a variety of things, because we have the "new, pythonic" way and the "old, backwards-compatible way". So it's no longer clear which is the fastest - and in the case of generators versus list comprehensions, it's not clear which you should be using. To bad. http://www.mired.org/home/mwm/ Independent WWW/Perforce/FreeBSD/Unix consultant, email for more information. -- http://mail.python.org/mailman/listinfo/python-list
Re: func_code vs. string problem
Filip Dreger wrote:
Uzytkownik "Steven Bethard" <[EMAIL PROTECTED]> napisal w
wiadomosci news:[EMAIL PROTECTED]
See the documentation:
http://docs.python.org/ref/dynamic-features.html
"""The eval(), execfile(), and input() functions and the exec
statement do not have access to the full environment for resolving
names. Names may be resolved in the local and global namespaces of
the caller. Free variables are not resolved in the nearest enclosing
namespace, but in the global namespace."""
Thank you! I feel silly I have not found the piece of instruction
myself. And even worse, as I still do not understand: if exec()
resolves free bariable names in the global namespace, how come it
works well with code in a string? Or with a code in a compiled string?
Well, probably the best thing to do is to check out what byte-code is
generated in each case:
py> s = compile('print b', 'string', 'exec')
py> def f():
... print b
...
py> import dis
py> dis.dis(s)
1 0 LOAD_NAME0 (b)
3 PRINT_ITEM
4 PRINT_NEWLINE
5 LOAD_CONST 0 (None)
8 RETURN_VALUE
py> dis.dis(f)
2 0 LOAD_GLOBAL 0 (b)
3 PRINT_ITEM
4 PRINT_NEWLINE
5 LOAD_CONST 0 (None)
8 RETURN_VALUE
So, the code is basically identical, except that with the string, the
code uses LOAD_NAME, while with the function, the code uses LOAD_GLOBAL.
Note that this is because Python can tell that b is not defined in the
function, and so it assumes that is must be a global lookup. Look what
happens if I give f a parameter:
py> def f(b):
... print b
...
py> dis.dis(f)
2 0 LOAD_FAST0 (b)
3 PRINT_ITEM
4 PRINT_NEWLINE
5 LOAD_CONST 0 (None)
8 RETURN_VALUE
Now f is using LOAD_FAST, which looks at the locals. I believe the
point of LOAD_GLOBAL and LOAD_FAST (instead of always using LOAD_NAME)
is to increase performance in the common case, where exec is not used.
Seems like the documentation is being a little conservative -- it does
look like some statements will do the lookup in the locals too... If I
was more confident about what goes on here, I'd probably try to file a
documentation bug...
The manual says I can pass two dictionaries to exec, one for global
namespace and one for local. But, strange as it seems, I could not get
it to work. In the example I gave, changing exec f.func_code to exec
f.func_code in globals(),locals() does not help a bit.
That's because, as the dis.dis output above shows, the function you've
defined is only searching the global namespace. So the locals() dict
you pass won't ever be looked at.
[snip example using locals as globals]
I thought about that... I don't know why, but it seems wrong. Maybe
the updating dictionaries is not very expensive, but there must be
some better way. This code has a 'workaround - fixme' written all over
it.
Yeah, I agree. On the other hand, whenever I see exec, it has
'workaround - fixme' written all over it too. ;)
STeVe
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Re: func_code vs. string problem
Uzytkownik "Steven Bethard" <[EMAIL PROTECTED]> napisal w wiadomosci news:[EMAIL PROTECTED] > See the documentation: > > http://docs.python.org/ref/dynamic-features.html > > """The eval(), execfile(), and input() functions and the exec > statement do not have access to the full environment for resolving > names. Names may be resolved in the local and global namespaces of > the caller. Free variables are not resolved in the nearest enclosing > namespace, but in the global namespace.""" Thank you! I feel silly I have not found the piece of instruction myself. And even worse, as I still do not understand: if exec() resolves free bariable names in the global namespace, how come it works well with code in a string? Or with a code in a compiled string? > Note the last sentence, which tells you that your free variable, > 'abc', will be resolved in the *global* namespace. In your > particular problem, you can solve this by substituting your local > namespace for the global namespace. This particular problem - sadly - is a simplified version of the real one. I need access to both: global and local namespaces, so this solution is not for me. The manual says I can pass two dictionaries to exec, one for global namespace and one for local. But, strange as it seems, I could not get it to work. In the example I gave, changing exec f.func_code to exec f.func_code in globals(),locals() does not help a bit. > One possible workaround might be: > > py> class foo: > ... def test(self): > ... print "ABC" > ... def checkfunction(self): > ... abc=10 > ... l = locals() > ... l.update(globals()) > ... exec myfunction.func_code in l > ... def checkstring(self): > ... abc=10 > ... exec "print abc;self.test()" > ... > py> foo().checkfunction() > __main__.foo > 10 > ABC I thought about that... I don't know why, but it seems wrong. Maybe the updating dictionaries is not very expensive, but there must be some better way. This code has a 'workaround - fixme' written all over it. Up to now, each time I encountered such a workaroundish solution, it turned out Python has a cleaner way to do it. I sure hope this is also the case here :-). > But I'd have to know what your real use case is to tell you whether > or not this is worth the trouble. Why do you want to exec the > func_code anyway? Why can't you just call the function? I put the description in the other post. Perhaps it's jkust my design that's broken. Thanks again. regards, Filip Dreger -- http://mail.python.org/mailman/listinfo/python-list
Why is Python not supporting full derivation of built-in file class?
Greetings,
I'm wondering why the >> operator does not use the write() method of a
class derived from the built-in file class as in DerivedFile below.
In the following example:
- StringFile is just a file-like string accumulation class that can be
used in place of a real file to accumulate strings that would otherwise
be printed. Works fine, can accumulate strings with the >> operator,
but is not a true file.
- DelegatedFile is a new-style class, a true file class, which provides
all the features of a real file through delegation. It also works fine
and can accumulate string with the >> operator.
- DerivedFile is a new-style class that is derived from file. It
behaves like a true file, but the >> operator does not call its write()
method. Why is that?
Is this related to the fact that on object from that class is seen as a
file (as shown at the end of the code session below)?
Is this intended or is it a flaw in the language that is waiting to be
fixed?
>>> import sys
>>> sys.ps2=' ... '; sys.ps1=' >>> '
>>> def hello(stream=None):
... if stream is None:
... stream = sys.stdout
... print >> stream, "Bonjour!"
...
>>> # Using a duck-typing to define a class
... # that behaves like a file for writing only.
... class StringFile:
... "A file-like object to accumulate strings"
... # print >> aStringFile works
... def __init__(self):
... self.strings = []
... def write(self, text):
... self.strings.append(text)
... def writelines(self, lines):
... self.strings.extend(lines)
...
>>> # Using delegation to file to create a class that
... # extends the built-in file object.
... class DelegatedFile(object):
... "A file-like object to accumulate strings"
... # print >> aStringFile works
... def __init__(self, *args):
... self.strings = []
... self._file = file(*args)
... def __getattr__(self, name) :
... return getattr(self._file, name)
... def write(self, text):
... self.strings.append(text)
... self._file.write(text)
... def writelines(self, lines):
... self.strings.extend(lines)
... self._file.writelines(lines)
...
>>> # Using derivation from file to create a class
... # that extends file. But has a flaw in the use of the >> operator!
... class DerivedFile(file):
... "A file object that accumulated written strings"
... # print >> a DerivedFile doe NOT work!
... def __init__(self, *args):
... self.strings = []
... file.__init__(self, *args)
... def write(self, text):
... self.strings.append(text)
... file.write(self, text)
... # super(DerivedFile, self).write(text)
... def writelines(self, lines):
... self.strings.extend(lines)
... file.writelines(self, lines)
... # super(DerivedFile, self).writelines(lines)
...
>>> hello()
Bonjour!
>>>
>>> sf = StringFile()
>>> hello(sf)
>>> sf.strings
['Bonjour!', '\n']
>>>
>>> dg = DelegatedFile("temp.txt","w")
>>> hello(dg)
>>> dg.close()
>>> dg.strings
['Bonjour!', '\n']
>>> for line in file("temp.txt"): print line
...
Bonjour!
>>> df = DerivedFile("temp2.txt","w")
>>> hello(df)
>>> df.close()
>>> df.strings
[]
>>> for line in file("temp2.txt"): print line
...
Bonjour!
>>>
>>> sf
<__main__.StringFile instance at 0x008D86C0>
>>> dg
<__main__.DelegatedFile object at 0x008D50B0>
>>> df
>>>
--
Pierre Rouleau
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Re: func_code vs. string problem
Filip Dreger wrote: If I had a magic function 'exec in current scope' I would implement it like this: class actor: def __init__(): self.roles=[] def act(): for i in self.roles: exec i in current scope then the roles would simply be functions defined in any importable file. For example creating an actor that logs each time it is called would be as simple as: import actor def log(): self.counter+=1 print "called %d times"%self.counter a=actor.actor() a.counter=0 a.roles.append(log) Any reason you can't define it like: class actor(object): def __init__(self): self.roles = [] def act(self): for role_func in self.roles: role_func(self) And then write your other modules like: import actor def log(self): self.counter += 1 print "called %d times"%self.counter a = actor.actor() a.counter = 0 a.roles.append(log) The only real difference here is that log is basically declared as an instance method. So if you need to update actor.actor state, you simply modify the self object. 2. I need the roles to have full access to global and local namespace of the actor object (sometimes they have to change it, and sometimes they have to use some external modules) - the roles should work like plugins. By importing actor, they have full access to the global namespace of the actor.actor object, by simply accessing the actor module attributes. So the issue here is really about full *local* namespace access. Do you really need *full* local namespace access? Why isn't access to the actor.actor instance sufficient? STeVe -- http://mail.python.org/mailman/listinfo/python-list
Re: Python or PHP?
Mage wrote:
However one of the worst cases is the sql injection attack. And sql
injections must be handled neither by php nor by python but by the
programmer.
But Python's DB-API (the standard way to connect to an SQL database from
Python) makes escaping SQL strings automatic. You can do this:
cursor.execute('UPDATE foo SET bar=%s WHERE id=%s', ["foo'bar", 123])
And "foo'bar" will be implicitly escaped to whatever is appropriate for
your database. How's that for Python handling SQL injection automatically?
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Re: func_code vs. string problem
Uzytkownik "Steven Bethard" <[EMAIL PROTECTED]> napisal w wiadomosci news:[EMAIL PROTECTED] > Filip Dreger wrote: >> I am trying to find a way of executing functions without creating a >> nested scope, so they can share local and global namespace (even if >> they are declared in some other module). > > Why? Can you explain what the use case is? I have a large set of objects of a single class - 'actor'. They are created all at once, and they all live in a sort of container written in C. The methods of the functions are few and general. One of them is simply 'act()', that is called by the C program every X seconds (tics, whatever). Each object can play 0..N roles, and the roles played by an object often change during its lifetime. The roles should be played in the act() method. Also, the roles should be defined in some simple way, and in an external python file (so adding/removing roles does not require recompiling of the parts embedded in C). If I had a magic function 'exec in current scope' I would implement it like this: class actor: def __init__(): self.roles=[] def act(): for i in self.roles: exec i in current scope then the roles would simply be functions defined in any importable file. For example creating an actor that logs each time it is called would be as simple as: import actor def log(): self.counter+=1 print "called %d times"%self.counter a=actor.actor() a.counter=0 a.roles.append(log) Let me recapitulate (is that the right English word?): 1. I need to keep the definitions of roles in a separate file (they can not simply be additional methods) 2. I need the roles to have full access to global and local namespace of the actor object (sometimes they have to change it, and sometimes they have to use some external modules) - the roles should work like plugins. 3. I guess I also need a fresh look at the problem. Maybe I am simply going the wrong way? I am more than willing to change my design, if someone shows me the light :-) regards, Filip Dreger -- http://mail.python.org/mailman/listinfo/python-list
Re: Handling lists
On Saturday 23 April 2005 12:50 pm, [EMAIL PROTECTED] wrote: > I have a question on python lists. > Suppose I have a 2D list > list = [[10,11,12,13,14,78,79,80,81,300,301,308]] > how do I convert it so that I arrange them into bins . > so If i hvae a set of consecutive numbers i would like to represent > them as a range in the list with max and min val of the range alone. > I shd get something like > list = [[10,14],[78,81],[300,308]] Here is an interesting way: >>> a = iter([1,2,3,4]) >>> [(b,a.next()) for b in a] [(1, 2), (3, 4)] James -- James Stroud UCLA-DOE Institute for Genomics and Proteomics Box 951570 Los Angeles, CA 90095 http://www.jamesstroud.com/ -- http://mail.python.org/mailman/listinfo/python-list
Re: memory profiler?
On Wed, 20 Apr 2005 23:06:51 -0400, Peter Hansen <[EMAIL PROTECTED]> wrote: > John Reese wrote: >> Is there a memory or heap profiler for python programs? So that, for >> example, if a program was bloating over time I could see how many of >> each object there were and maybe even where the references were? > > The "gc" module has a variety of helpful features > like that. > > -Peter In particular, get_objects() and get_referrers(). Good point. -- http://mail.python.org/mailman/listinfo/python-list
Re: Using Ming on Windows
On Sat, Apr 23, 2005 at 05:13:29PM -0300, Andr? Roberge wrote: > I tried to install Ming > (http://sourceforge.net/projects/ming/) > on Windows to use with Python *but* > I can't [/don't know how to] use "make" to install it. > > Does anyone know where I could find a ready-made compiled > version for Windows to just "put in" my site-packages directory. > > Any help would be appreciated. > Ming seems to be abandoded/unsupported. Use groups.google.com to find some hints on how to install it. I've done it on linux, but never tried on windows (why would I?) and replied with some suggestions last time it came up on c.l.py -jackdied -- http://mail.python.org/mailman/listinfo/python-list
Re: XML file parsing with SAX
On 4/23/05, Willem Ligtenberg <[EMAIL PROTECTED]> wrote: > so that will be sax.handler.feature_external_ges = "false" Yes. > And it will work? Honestly, I'm not sure. It should, but I've found these edge cases a bit hard to predict in the Python built-in libs :-( > But what about using a catalog? I am very new to python and XML... Catalogs allow you to rewrite the IDs for entities and such. So if you had an XML file with an entity at a URL, but you were working offline, you could use a catalog to "redirect" the entity to a copy on your local filesystem. Problem, now that I think of it, is that I'm not sure you can specify an catalog in PySAX. You might instead have to override the method entityResolver in your handler (and be sure to ). See the example in listing 1 and and discussion here: http://www.xml.com/pub/a/2005/03/02/pyxml.html Good luck. -- Uche Ogbuji Fourthought, Inc. http://uche.ogbuji.nethttp://fourthought.com http://copia.ogbuji.net http://4Suite.org Use CSS to display XML, part 2 - http://www-128.ibm.com/developerworks/edu/x-dw-x-xmlcss2-i.html XML Output with 4Suite & Amara - http://www.xml.com/pub/a/2005/04/20/py-xml.htmlUse XSLT to prepare XML for import into OpenOffice Calc - http://www.ibm.com/developerworks/xml/library/x-oocalc/ Schema standardization for top-down semantic transparency - http://www-128.ibm.com/developerworks/xml/library/x-think31.html -- http://mail.python.org/mailman/listinfo/python-list
Re: func_code vs. string problem
Filip Dreger wrote: I am trying to find a way of executing functions without creating a nested scope, so they can share local and global namespace (even if they are declared in some other module). Why? Can you explain what the use case is? STeVe -- http://mail.python.org/mailman/listinfo/python-list
Re: func_code vs. string problem
Filip Dreger wrote: Each function has a func_code property that is suposed to contain the pure bytecode of the function. All the context (including reference to relevant namespaces) is stored in different fields of the function object. Since 'exec' is able to execute any string or bytecode in the current scope, it would seem possible to execute code of any function in any namespace. But no matter how I tried, I could not do it. There must be something I am missing. Here's what I do:(if anyone wants to help, I placed the source under http://www.bajobongo.net/foo.py - tested on Python 2.4.1) 1. I declare a function. In the next steps I will try to run its code from inside a class: def myfunction(): print abc self.test() 2. I declare a class foo, with two methods. The first one tries to reach some local variables from a string passed to exec. The other one tries to do the same from inside a bytecode (from myfunction). IMHE this should make no difference to 'exec' - [spoiler: it does]. class foo: def test(self): print "ABC" def checkfunction(self): abc=10 exec myfunction.func_code def checkstring(self): abc=10 exec "print abc;self.test()" 3. I test the both methods. Sadly, the 'checkfunction' fails to find the correct namespace (id does not see 'abc' nor 'self'). Adding things like: "exec myfunction.func_code in globals(),locals()" does not help. i=foo() i.checkstring() i.checkfunction() # this throws exception; why??? See the documentation: http://docs.python.org/ref/dynamic-features.html """The eval(), execfile(), and input() functions and the exec statement do not have access to the full environment for resolving names. Names may be resolved in the local and global namespaces of the caller. Free variables are not resolved in the nearest enclosing namespace, but in the global namespace.""" Note the last sentence, which tells you that your free variable, 'abc', will be resolved in the *global* namespace. In your particular problem, you can solve this by substituting your local namespace for the global namespace: py> def myfunction(): ... print abc ... self.test() ... py> class foo: ... def test(self): ... print "ABC" ... def checkfunction(self): ... abc=10 ... exec myfunction.func_code in locals() ... def checkstring(self): ... abc=10 ... exec "print abc;self.test()" ... py> foo().checkstring() 10 ABC py> foo().checkfunction() 10 ABC But note that if your code actually needs access to any globals, it's out of luck: py> def myfunction(): ... print foo ... print abc ... self.test() ... py> foo().checkfunction() Traceback (most recent call last): File "", line 1, in ? File "", line 6, in checkfunction File "", line 2, in myfunction NameError: global name 'foo' is not defined One possible workaround might be: py> class foo: ... def test(self): ... print "ABC" ... def checkfunction(self): ... abc=10 ... l = locals() ... l.update(globals()) ... exec myfunction.func_code in l ... def checkstring(self): ... abc=10 ... exec "print abc;self.test()" ... py> foo().checkfunction() __main__.foo 10 ABC But I'd have to know what your real use case is to tell you whether or not this is worth the trouble. Why do you want to exec the func_code anyway? Why can't you just call the function? STeVe -- http://mail.python.org/mailman/listinfo/python-list
Re: Handling lists
yes that makes sense.But the problem I am facing is if list= [300,301,303,305] I want to consider it as one cluster and include the range as [300,305] so this is where I am missing the ranges. so If the list has l = [300,301,302,308,401,402,403,408] i want to include it as [[300,308],[401,408]]. -- http://mail.python.org/mailman/listinfo/python-list
Re: XML file parsing with SAX
I didn't make the XML file. And I don't like messing with other peoples
data. So I just want my SAX parser to ignore it. I can't help if other
people make it hard for me to read their xml file...
On Sat, 23 Apr 2005 13:48:49 -0600, Uche Ogbuji wrote:
> On Sat, 2005-04-23 at 15:20 +0200, Willem Ligtenberg wrote:
>> I decided to use SAX to parse my xml file.
>> But the parser crashes on:
>> File "/usr/lib/python2.3/site-packages/_xmlplus/sax/handler.py", line 38,
>> in fatalError
>> raise exception
>> xml.sax._exceptions.SAXParseException: NCBI_Entrezgene.dtd:8:0: error in
>> processing external entity reference
>>
>> This is caused by:
>> > "NCBI_Entrezgene.dtd">
>>
>> If I remove it, it parses normally.
>> I've created my parser like this:
>> import sys
>> from xml.sax import make_parser
>> from handler import EntrezGeneHandler
>>
>> fopen = open("mouse2.xml", "r")
>> ch = EntrezGeneHandler()
>> saxparser = make_parser()
>> saxparser.setContentHandler(ch)
>> saxparser.parse(fopen)
>>
>> And the handler is:
>> from xml.sax import ContentHandler
>>
>> class EntrezGeneHandler(ContentHandler):
>> """
>> A handler to deal with EntrezGene in XML
>> """
>>
>> def startElement(self, name, attrs):
>> print "Start element:", name
>>
>> So it doesn't do much yet. And still it crashes...
>> How can I tell the parser not to look at the DOCTYPE declaration.
>> On a website:
>> http://www.devarticles.com/c/a/XML/Parsing-XML-with-SAX-and-Python/1/
>> it states that the SAX parsers are not validating, so this error shouldn't
>> even occur?
>
> Just because it's not validating doesn't mean that the parser won't try
> to read the external entity.
>
> Maybe you're looking for
>
> """
> feature_external_ges
> Value: "http://xml.org/sax/features/external-general-entities";
> true: Include all external general (text) entities.
> false: Do not include external general entities.
> access: (parsing) read-only; (not parsing) read/write
> """
>
> Quote from:
>
> http://docs.python.org/lib/module-xml.sax.handler.html
>
> But you're on pretty shaky ground in any XML 1.x toolkit using a bogus
> DTDecl in this way. Why go through the hassle? Why not use a catalog,
> or remove the DTDecl?
--
http://mail.python.org/mailman/listinfo/python-list
Re: func_code vs. string problem
I came up with a simpler description of the problem. It's all in the simple source: # we define 'print b' in three different ways: as a string, # a bytecode and a function string="print b" code=compile(string,'string','exec') def function(): print b # now we make functions that test if it is possible to execute 'print b' # in some local scope def execstring(): b=5 exec string def execfunction(): b=5 exec function.func_code def execcode(): b=5 exec code execstring() # works execcode() # works execfunction() # throws name error exception... My problem is that both 'string' and 'code' are references to code objects, so they _should_ behave in the same way... I am close to giving up... I am trying to find a way of executing functions without creating a nested scope, so they can share local and global namespace (even if they are declared in some other module). I _could_ turn them into strings and pass around as compiled objects, butthis would be very ugly. I am sure Python has some better, cleaner way to do this. regards, Filip Dreger -- http://mail.python.org/mailman/listinfo/python-list
Bounding box on clusters in a 2D list
If I have ex: x = [[1,1,1,0,0,0,0,0,0,0,0,1,1,1,1,0,0,0], [1,1,1,0,1,1,0,0,0,0,0,1,1,1,1,0,0,0], [1,1,1,0,1,1,1,0,1,1,0,1,1,1,0,0,0,0], [0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0]] what I want is a boundingbox over the region where we find clusters of 1's.So for instance in the above list first 3 roes and colums have 1's so the area of that box is 3x3 so my final array should have an array of approx areas of clusters of 1's like area = [ 9,4 ] Hope I am clear with my question. -- http://mail.python.org/mailman/listinfo/python-list
Re: Does numarray search for blas and lapack during installation?
IIRC, no. But the setup.py script is fairly easy to hack to link in your own blas/lapack libraries. -- http://mail.python.org/mailman/listinfo/python-list
Re: Python or PHP?
Le Sat, 23 Apr 2005 19:11:19 +0200, Fredrik Lundh a écrit : > in PHP, good programmers are able to write bad programs without > even noticing. +1 QOTW --- The use of COBOL cripples the mind; its teaching should, therefore, be regarded as a criminal offense. Dr. E.W. Dijkstra -- http://mail.python.org/mailman/listinfo/python-list
Re: Handling lists
[EMAIL PROTECTED] wrote: >I have a question on python lists. >Suppose I have a 2D list >list = [[10,11,12,13,14,78,79,80,81,300,301,308]] >how do I convert it so that I arrange them into bins . >so If i hvae a set of consecutive numbers i would like to represent >them as a range in the list with max and min val of the range alone. >I shd get something like >list = [[10,14],[78,81],[300,308]] > > > Maybe: list = [10,11,12,13,14,78,79,80,81,300,301,308] new_list = [] start = 0 for i in range(1,len(list) + 1): if i == len(list) or list[i] - list[i-1] <> 1: new_list.append([list[start],list[i-1]]) start = i print new_list -- http://mail.python.org/mailman/listinfo/python-list
Using Ming on Windows
I tried to install Ming (http://sourceforge.net/projects/ming/) on Windows to use with Python *but* I can't [/don't know how to] use "make" to install it. Does anyone know where I could find a ready-made compiled version for Windows to just "put in" my site-packages directory. Any help would be appreciated. André -- http://mail.python.org/mailman/listinfo/python-list
Handling lists
I have a question on python lists. Suppose I have a 2D list list = [[10,11,12,13,14,78,79,80,81,300,301,308]] how do I convert it so that I arrange them into bins . so If i hvae a set of consecutive numbers i would like to represent them as a range in the list with max and min val of the range alone. I shd get something like list = [[10,14],[78,81],[300,308]] -- http://mail.python.org/mailman/listinfo/python-list
Re: XML file parsing with SAX
On Sat, 2005-04-23 at 15:20 +0200, Willem Ligtenberg wrote:
> I decided to use SAX to parse my xml file.
> But the parser crashes on:
> File "/usr/lib/python2.3/site-packages/_xmlplus/sax/handler.py", line 38,
> in fatalError
> raise exception
> xml.sax._exceptions.SAXParseException: NCBI_Entrezgene.dtd:8:0: error in
> processing external entity reference
>
> This is caused by:
> "NCBI_Entrezgene.dtd">
>
> If I remove it, it parses normally.
> I've created my parser like this:
> import sys
> from xml.sax import make_parser
> from handler import EntrezGeneHandler
>
> fopen = open("mouse2.xml", "r")
> ch = EntrezGeneHandler()
> saxparser = make_parser()
> saxparser.setContentHandler(ch)
> saxparser.parse(fopen)
>
> And the handler is:
> from xml.sax import ContentHandler
>
> class EntrezGeneHandler(ContentHandler):
> """
> A handler to deal with EntrezGene in XML
> """
>
> def startElement(self, name, attrs):
> print "Start element:", name
>
> So it doesn't do much yet. And still it crashes...
> How can I tell the parser not to look at the DOCTYPE declaration.
> On a website:
> http://www.devarticles.com/c/a/XML/Parsing-XML-with-SAX-and-Python/1/
> it states that the SAX parsers are not validating, so this error shouldn't
> even occur?
Just because it's not validating doesn't mean that the parser won't try
to read the external entity.
Maybe you're looking for
"""
feature_external_ges
Value: "http://xml.org/sax/features/external-general-entities";
true: Include all external general (text) entities.
false: Do not include external general entities.
access: (parsing) read-only; (not parsing) read/write
"""
Quote from:
http://docs.python.org/lib/module-xml.sax.handler.html
But you're on pretty shaky ground in any XML 1.x toolkit using a bogus
DTDecl in this way. Why go through the hassle? Why not use a catalog,
or remove the DTDecl?
--
Uche Ogbuji Fourthought, Inc.
http://uche.ogbuji.nethttp://fourthought.com
http://copia.ogbuji.net http://4Suite.org
Use CSS to display XML, part 2 -
http://www-128.ibm.com/developerworks/edu/x-dw-x-xmlcss2-i.html
XML Output with 4Suite & AMara - http://www.xml.com/pub/a/2005/04/20/py-xml.html
Use XSLT to prepare XML for import into OpenOffice Calc -
http://www.ibm.com/developerworks/xml/library/x-oocalc/
Schema standardization for top-down semantic transparency -
http://www-128.ibm.com/developerworks/xml/library/x-think31.html
--
http://mail.python.org/mailman/listinfo/python-list
python and Tile Studio
Has anyone used Python with Tile Studio to create games? http://tilestudio.sourceforge.net/ André -- http://mail.python.org/mailman/listinfo/python-list
Re: python modules in home dir
On Sat, 2005-04-16 at 08:12 -0600, Uche Ogbuji wrote: > On Sat, 2005-04-09 at 14:09 -0700, dzieciou wrote: > > > I'm new-comer in Python. > > I want to install few Python modules (4Suite, RDFLib, Twisted and Racoon) > > in my home directory, since Python installation is already installed in the > > system > > and I'm NOT its admin. > > I cannot install pyvm (portable binary python machine) - have no such big > > quota. > > Any idea how can I solve it? > > To install 4Suite in the home dir, use an incantation such as: > > ./setup.py config --prefix=$HOME/lib > ./setup.py install > > Note: I expect you also installed Python in your home dir? BTW, I expanded on this suggestion at: http://copia.ogbuji.net/blog/2005-04-16/Installing -- Uche Ogbuji Fourthought, Inc. http://uche.ogbuji.nethttp://fourthought.com http://copia.ogbuji.net http://4Suite.org Use CSS to display XML, part 2 - http://www-128.ibm.com/developerworks/edu/x-dw-x-xmlcss2-i.html XML Output with 4Suite & AMara - http://www.xml.com/pub/a/2005/04/20/py-xml.html Use XSLT to prepare XML for import into OpenOffice Calc - http://www.ibm.com/developerworks/xml/library/x-oocalc/ Schema standardization for top-down semantic transparency - http://www-128.ibm.com/developerworks/xml/library/x-think31.html -- http://mail.python.org/mailman/listinfo/python-list
Re: Python or PHP?
# [EMAIL PROTECTED] / 2005-04-23 15:53:17 +0200: > Lad wrote: > > >Is anyone capable of providing Python advantages over PHP if there are > >any? > > I am also new to python but I use php for 4 years. I can tell: > > - python is more *pythonic* than php > - python has its own perfume > http://www.1976.com.tw/image/trussardi_python_uomo.jpg and it's nice. > php doesn't have any smell > - writing python programs you feel much better No, *you* feel better. :) > check this: http://wiki.w4py.org/pythonvsphp.html The comparison found there is biased, the author is a Python partisan. -- How many Vietnam vets does it take to screw in a light bulb? You don't know, man. You don't KNOW. Cause you weren't THERE. http://bash.org/?255991 -- http://mail.python.org/mailman/listinfo/python-list
Re: Python or PHP?
On Sat, 23 Apr 2005 20:13:24 +0200, Mage wrote: > Avoid them is easy with set_type($value,"integer") for integer values and > correct escaping for strings. "Avoiding buffer overflows in C is easy, as long as you check the buffers each time." The *existence* of a technique to avoid problems is not in question. The problem is when the language makes it easier to *not* do the checks than to do the checks. Any look at the real world shows that that pattern causes trouble, and that clearly, the mere *existence* of a way to not get in trouble is not sufficient in the general case. Despite the fact that all you have to do to avoid cutting your finger off with a saw is not stick your finger in the saw, most people, even carpentry professionals, are going to want to use finger-guards and other safety equipment. A programmer turning down such security protection (without another good reason, which does happen), is being like the guy too macho to use the finger guard; stupidity induced by arrogance, not some one no longer using training wheels. Using PHP and futzing with SQL directly is probably not a good enough reason, as surely PHP has safer libraries available. (If not, my opinion of PHP goes down another notch.) Data binding with something like SQLObject makes it *easier* to be secure than insecure; barring an out-and-out bug in SQLObject (given the nature of the requisite bug, it is extremely unlikely to have survived this long), a programmer must go *way* out of their way to introduce the SQL injection attacks that so plague PHP projects. -- http://mail.python.org/mailman/listinfo/python-list
Re: Python or PHP?
Fredrik Lundh wrote: > >sql injection? what's your excuse for not using data binding? > > I am not sure I truly understand your question. So far my own servers didn't get successful sql injection attack. I just saw some on other sites and did one for demonstration. Avoid them is easy with set_type($value,"integer") for integer values and correct escaping for strings. However, php programmers usually don't initialize their variables because they don't have to do. They even turn off warnings and errors. Our php errorlog at my full time working company is so huge I could cry. We have php-copypasters. I don't know anyone IRL who uses python. So I started to learn it. Mage -- http://mail.python.org/mailman/listinfo/python-list
Re: PDF Printing support from Python
> You're use of the word "driver" is one with which I'm not > familiar. But I don't really "do windows" so it's probably a > Widnowism. It is a windowism but not exclusively ;). http://www.collaborium.org/onsite/romania/UTILS/Printing-HOWTO/winprinters.html This is the first link I found that mentioned drivers, but the last time I installed Linux-Mandrake I saw a document that went into detail about CUPS and windows printing. It seems that cups is available for windows( they also use the word driver ) http://www.cups.org/windows/index.php Ghostscript for windows available here http://www.ghostscript.com/ http://www.cs.wisc.edu/~ghost/ -- http://mail.python.org/mailman/listinfo/python-list
Re: Python or PHP?
"Mage" wrote: > I don't think so. Bad programmers are able to write bad programs in any > language. in PHP, good programmers are able to write bad programs without even noticing. (every successful server attack I've seen closely the last few years have been through PHP. it's totally without competition in this area) > However one of the worst cases is the sql injection attack. And sql > injections must be handled neither by php nor by python but by the > programmer. sql injection? what's your excuse for not using data binding? -- http://mail.python.org/mailman/listinfo/python-list
Re: Python Imaging Library and PyGTK - color image path?
On Sat, 23 Apr 2005 10:20:29 +0200, Fredrik Lundh wrote: > which discusses draw_rgb_image and friends, and says that "if you can > convert your PIL image to a pixel data string or buffer object, you could > use them to display the image". here's some code that seems to do exactly > that: > > http://www.mail-archive.com/pygtk@daa.com.au/msg07167.html > > (but maybe this is some kind of stupid "a bitmap isn't a pixmap isn't an > image" thing? if so, I suggest getting a modern windowing system ;-) A varient; I was missing the gdk.pixbuf because I assumed that because there was a gtk.pixbuf that I knew about, that I had all relevant data. Were that the only pixbuf, that would be an atrocity. (Particularly odd for GTK, the *Gimp* windowing toolkit.) (It of course figures that was the google search; I think I tried everything but that; "python imaging library" "pygtk" isn't anywhere near as helpful, for instance.) -- http://mail.python.org/mailman/listinfo/python-list
Does numarray search for blas and lapack during installation?
I have a PC with Debian sid installed. I install all my Python stuff in /usr/local. I just installed numarray 1.3.1. Blaslite and lapacklite were compiled. Did the installation process search for blas and lapack? -- http://mail.python.org/mailman/listinfo/python-list
Re: Python or PHP?
I've been a PHP and Perl programmer (amongst others) for 10 years or more now, and a Python coder for 3 or so. I have come to hate PHP now, it's pseudo-OOP is awful, it's dog slow at handling XML, it's so easy to use that most of the programmers I've had contact with are very sloppy and do things like extract($_GET); or put database usernames and passwords in index.php. I also have to agree that php.net/manual seems to be the main reference that coders use - which is not good if the comments are wrong! Python seems to force you to write better code, maybe because of the indentation, exception handling, proper OOP etc. Plus it's not so tied into web stuff, in fact most of my Python programming is for the desktop. I still love Perl, it's a bit of an art form, as "there's more than one way to do it", whereas Python usually only allows one way to do it, which may or may not be a better mantra I've come to allocate PHP the same standing as ASP, VB or Java - the language is OK, but the programmers are usually crap. -- http://mail.python.org/mailman/listinfo/python-list
Re: How to run Python in Windows w/o popping a DOS box?
On 22 Apr 2005 21:16:04 -0700, [EMAIL PROTECTED] wrote: >>>I think of it like the ''.join semantics. The object knows best how >to >>>handle join (even if it looks wierd to some people). In the #! case, >>>the program knows best how to start itself. > >>This I don't understand ;-) > >With ','.join(['a','b','c'])You rely on what wants to join the >sequence to handle the issue of joining rather than have the sequence >understand joining. I think of it as the object knows best. > >I think of #! as "the program knowing best" how to startup, rather >than having to rely on something else to deal with it. I also like the My point was that the "program" -- whether script or executable -- _is_ depending on something else, i.e., whatever is launching it in an appropriate environment, and my real point was that the launcher looks at the beginning of the file contents to check what to do, rather than looking at separate file metadata. I am objecting to embeddeding metadata in data. The convention of using a first #! line in scripts as metadata and passing the whole script to whatever interpreter means that the interpreters have to know to ignore the first line --usually meaning the '#' is a comment line start. Or else it has to be told with a command line option like python's -x to ignore extraneous metadata. Carrying metadata in file names and extensions is not better, just different, and brings a bag of problems, like having no identifier for the data per se, just its various containers. >text based simplicity and explictness. Just like text based "etc" files >on unix versus the registry in windows. And, if you want you can add >more power like use env variables in #!. >It can be as simple or as powerful as you need, you can use whatever >means you want to manage the #! line: text editors, other programs, >etc. It is data-centric, just like http, sql, file I/O rather than >verb-centric (learn another whole set of methods to figure out how to >change startup). I don't disagree about the usefulness of various text data, I just want to distinguish data from metadata and container identifiers from data identifiers. > >hopefully I am making sense, > I think we were just looking a different aspects of the elephant ;-) Regards, Bengt Richter -- http://mail.python.org/mailman/listinfo/python-list
Re: Trouble Installing TTX/FontTools (asks for .NET FrameworkPackages)
Jesper Olsen wrote: > > Apparently setup.py tries to compile a c file, which of course > doesn't > > work if there's no compiler. > > In fact it does not work even if there is a compiler - seems distutils > has been broken in python2.4 (it works in python2.3). distutils works just fine in 2.4. but the standard Windows distribution of Python 2.4 is compiled with a newer compiler. if you don't have a compatible compiler on your machine (or if the compiler isn't properly installed), setup won't be able to build extensions for 2.4. -- http://mail.python.org/mailman/listinfo/python-list
Re: Python or PHP?
"Lad" <[EMAIL PROTECTED]> writes: > Is anyone capable of providing Python advantages over PHP if there are > any? > Cheers, > L. PHP is strongly wedded to providing web-based content, while Python can be used to build a large number of different types of applications. -- Kirk Job-Sluder "The square-jawed homunculi of Tommy Hilfinger ads make every day an existential holocaust." --Scary Go Round -- http://mail.python.org/mailman/listinfo/python-list
func_code vs. string problem
Each function has a func_code property that is suposed to contain the pure bytecode of the function. All the context (including reference to relevant namespaces) is stored in different fields of the function object. Since 'exec' is able to execute any string or bytecode in the current scope, it would seem possible to execute code of any function in any namespace. But no matter how I tried, I could not do it. There must be something I am missing. Here's what I do:(if anyone wants to help, I placed the source under http://www.bajobongo.net/foo.py - tested on Python 2.4.1) 1. I declare a function. In the next steps I will try to run its code from inside a class: def myfunction(): print abc self.test() 2. I declare a class foo, with two methods. The first one tries to reach some local variables from a string passed to exec. The other one tries to do the same from inside a bytecode (from myfunction). IMHE this should make no difference to 'exec' - [spoiler: it does]. class foo: def test(self): print "ABC" def checkfunction(self): abc=10 exec myfunction.func_code def checkstring(self): abc=10 exec "print abc;self.test()" 3. I test the both methods. Sadly, the 'checkfunction' fails to find the correct namespace (id does not see 'abc' nor 'self'). Adding things like: "exec myfunction.func_code in globals(),locals()" does not help. i=foo() i.checkstring() i.checkfunction() # this throws exception; why??? 4. I try to find some help here, and hope to also gain better undesrtanding of how Python works :-) Thanks for any suggestions, regards, Filip Dreger -- http://mail.python.org/mailman/listinfo/python-list
Re: Python or PHP?
Tim Tyler wrote: >Mage <[EMAIL PROTECTED]> wrote or quoted: > > > >>check this: http://wiki.w4py.org/pythonvsphp.html >> >> > >Good - but it hardly mentions the issue of security - which seems >like a bit of a problem for PHP at the moment. > > I don't think so. Bad programmers are able to write bad programs in any language. Maybe there are more bad php programmers than python programmers and the 70% of the dynamic world wide web is copied from user comments in the php.net/manual. However one of the worst cases is the sql injection attack. And sql injections must be handled neither by php nor by python but by the programmer. I think a website or even a large portal is a well constructed database with triggers and stored procedures and some "echo", "if", "foreach" and "while" in the php code. To me the advantage of python seems to come out when you deal with xml, file handling or when you have to write a native server application for your website. But I am so new here, others may say other things. Mage -- http://mail.python.org/mailman/listinfo/python-list
Re: XML parsing per record
Willem Ligtenberg wrote: Is there an easy way, to couple data together. Because I have discoverd an irritating feature in the xml file. Sometimes this is a database reference: UCSC 1234 And sometimes: UCSC 1234 So I get a list database names and two! lists of ID's And those two are in no way related. Is there an easy way to create a dictionary like this DBname --> ID If not, I still might need to revert to SAX... :( None of your requirements sound particularly difficult to implement. If you would post a complete example of the data you want to parse and the data you would like to end up it would be easier to help you. The sample data you posted originally does not have many of the fields you want to extract and your example of what you want to end up with is not too clear either. If you are having trouble with ElementTree I expect you will be completely lost with SAX, ElementTree is much easier to work with and cElementTree is very fast. Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: a=[ lambda t: t**n for n in range(4) ]
On 22 Apr 2005 20:45:55 -0700, "El Pitonero" <[EMAIL PROTECTED]> wrote: >Bengt Richter wrote: >> I still don't know what you are asking for, but here is a toy, >> ... >> But why not spend some time with the tutorials, so have a few more >cards in your deck >> before you try to play for real? ;-) > >Communication problem. Indeed. > >All he wanted is automatic evaluation a la spreadsheet application. >Just like in Microsoft Excel. That's all. > >There are many ways for implementing the requested feature. Here are >two: > >(1) Push model: use event listeners. Register dependent quantities as >event listeners of independent quantities. When an independent quantity >is modified, fire off the event and update the dependent quantities. >Excel uses the push model. This is essentially what I was demonstrating with the namespace of FunArray, showing object attribute namespace access as perhaps _the_ 'listening" hook of Python -- which properties and overriding base class methods with subclass methods etc. etc. all depend on. FunArray 'listens' for named "spreadsheet cell" assignments to its namespace, and it "listens" for a repr access to the "spreadsheet" as a whole, presenting its status in terms of cell names and the formula value of the last cell entered. Not conventional, but I wanted to stay as close to the OP's proposed example interactive log (if that was what it was, which apparently it wasn't ;-) This does also demonstrate that if you want to "listen" for apparent assignments to bare names, AFAIK there is no way without byte code hackery or using a trace hook, or just doing your own eval-print loop, which is why I suggested the cmd module as a start. of course, you could mess with displayhook to get what the OP originally appeared to be asking for. E.g., this toy produces an interactive log much like the OP specified: >>> class DH(object): ... def __init__(self): ... import math ... self.env = vars(math) ... self.env.update(vars(__builtins__)) ... def evalstrex(self, s): ... for name in compile(s,'','eval').co_names: ... if type(self.env[name]) == str: ... self.env[name] = self.evalstrex(self.env[name]) ... return eval(s, self.env) ... def __call__(self, o): ... if type(o)==str: ... self.env.update(globals()) ... o = self.evalstrex(o) ... sys.__displayhook__(o) ... >>> import sys >>> sys.displayhook = DH() Other than the quotes around the formula, >>> a = '[sin(x), cos(x)]' >>> x=0.0 >>> a [0.0, 1.0] >>> x=1.0 >>> a [0.8414709848078965, 0.54030230586813977] looks a lot like """ I'm looking for array of functions. Something like a=[ sin(x) , cos(x) ] >>> x=0.0 >>> a [0, 1] >>> x=1.0 >>> a ... of course it can be made by >>> def cratearray(x): ... ... return a a=createarray(1.0) but this isn't what i am asking for. something automized. """ Of course, this is not what the OP _really_ wanted ;-) But it's kind of fun. Anything you type in quotes is evaluated using available global bindings plus the ones in the math module and __builtins__, and it's recursive, so if a name in the quoted formula refers to another string (which must be a valid expression), that is evaluated, and so on. This is "pull" based on interactive display trigger ;-) >>> x='pi/6' >>> a [0.49994, 0.86602540378443871] >>> x='pi/6' >>> a [0.49994, 0.86602540378443871] >>> x = 'pi/y' >>> y=6 >>> a [0.49994, 0.86602540378443871] >>> y=3 >>> a [0.8660254037844386, 0.50011] The display hook passes through non-strings, so you can box a string formula to see it: >>> [a] ['[sin(x), cos(x)]'] >>> [x] ['pi/y'] >>> [y] [3] You could specify your spread sheet: >>> a1,a2,a3=100,200,'sum([a1,a2])' >>> a1,a2,a3 (100, 200, 'sum([a1,a2])') >>> a1 100 >>> a2 200 >>> a3 300 ;-) > >(2) Pull model: lazy evaluation. Have some flag on whether an >independent quantity has been changed. When evaluating a dependent >quantity, survey its independent quantities recursively, and update the >cached copies whereever necessary. > >Of course, combination of the two approaches is possible. > >For Python, metaclasses and/or decorators and/or properties may help. > >But functional languages are a more natural territory. > Regards, Bengt Richter -- http://mail.python.org/mailman/listinfo/python-list
Re: Python licence again
fuzzylollipop <[EMAIL PROTECTED]> wrote or quoted: > try spelling license correctly next time and heading the google > suggestions that probably looked like "didn't you mean : Python License" How do you spell license correctly? -- __ |im |yler http://timtyler.org/ [EMAIL PROTECTED] Remove lock to reply. -- http://mail.python.org/mailman/listinfo/python-list
Re: Python or PHP?
Mage <[EMAIL PROTECTED]> wrote or quoted: > check this: http://wiki.w4py.org/pythonvsphp.html Good - but it hardly mentions the issue of security - which seems like a bit of a problem for PHP at the moment. -- __ |im |yler http://timtyler.org/ [EMAIL PROTECTED] Remove lock to reply. -- http://mail.python.org/mailman/listinfo/python-list
Re: Trouble Installing TTX/FontTools (asks for .NET Framework Packages)
weston wrote: > This problem may be addressed here: > > http://sourceforge.net/mailarchive/message.php?msg_id=1702374 > > Apparently setup.py tries to compile a c file, which of course doesn't > work if there's no compiler. In fact it does not work even if there is a compiler - seems distutils has been broken in python2.4 (it works in python2.3). Jesper -- http://mail.python.org/mailman/listinfo/python-list
Re: Python or PHP?
> php doesn't have any smell au contraire! I've seen many code smells in PHP. http://c2.com/cgi/wiki?CodeSmell -- Regards, Diez B. Roggisch -- http://mail.python.org/mailman/listinfo/python-list
Re: Python or PHP?
> "Leif" == Leif K-Brooks <[EMAIL PROTECTED]> writes: Leif> Lad wrote: >> Is anyone capable of providing Python advantages over PHP if there are >> any? Leif> Python is a programming language in more ways than simple Turing Leif> completeness. PHP isn't. +1 QOTW. -- Ville Vainio http://tinyurl.com/2prnb -- http://mail.python.org/mailman/listinfo/python-list
Re: Frog 1.4 (web log aka blogging server)
limodou wrote: great! How about change the bbcode like editor to FCKeditor? I think FCKeditor is much better, or make it as an optional editor which the user could select it himself. Isn't that pretty heavyweight for a blog? I mean; Frog is not a CMS with which you write HTML pages... Then again, it shouldn't be very hard to switch de default formatting engine for another one, the code is already somewhat prepared for this. I'd say, give it a shot :) Patches are gladly accepted. (I'll put this as a nice-to-have on the list) --Irmen 2005/4/23, Irmen de Jong <[EMAIL PROTECTED]>: I've released a new version of Frog, a web log aka blogging server written in 100% python. [...] -- http://mail.python.org/mailman/listinfo/python-list
Caching compiled regexps across sessions (was Re: Regular Expressions - Python vs Perl)
> "Ilpo" == Ilpo NyyssÃnen writes: >> so you picked the wrong file format for the task, and the slowest Ilpo> What would you recommend instead? Ilpo> I have searched alternatives, but somehow I still find XML Ilpo> the best there is. It is a standard format with standard Ilpo> programming API. Ilpo> I don't want to lose my calendar data. XML as a standard Ilpo> format makes it easier to convert later to some other Ilpo> format. As a textual format it is also readable as raw also Ilpo> and this eases debugging. Use pickle, perhaps, for optimal speed and code non-ugliness. You can always use xml as import/export format, perhaps even dumping the db to xml at the end of each day. Ilpo> And my point is that the regular expression compilation can Ilpo> be a problem in python. The current regular expression Ilpo> engine is just unusable slow in short lived programs with a Ilpo> bit bigger amount of regexps. And fixing it should not be Ilpo> that hard: an easy improvement would be to add some kind of Ilpo> storing mechanism for the compiled regexps. Are there any Ilpo> reasons not to do this? It should start life as a third-party module (perhaps written by you, who knows :-). If it is deemed useful and clean enough, it could be integrated w/ python proper. This is clearly something that should not be in the python core, because the regexps themselves aren't there either. >> python has shipped with a fast XML parser since 2.1, or so. Ilpo> With what features? validation? I really want a validating Ilpo> parser with a DOM interface. (Or something better than DOM, Ilpo> must be object oriented.) Check out (coincidentally) Fredrik's elementtree: http://effbot.org/zone/element-index.htm Ilpo> I don't want to make my programs ugly (read: use some more Ilpo> low level interface) and error prone (read: no validation) Ilpo> to make them fast. Why don't you use external validation on the created xml? Validating it every time sounds like way too much like Javaic B&D to be fun anymore. Pickle should serve you well, and would probably remove about half of your code. "Do the simplest thing that could possibly work" and all that. -- Ville Vainio http://tinyurl.com/2prnb -- http://mail.python.org/mailman/listinfo/python-list
Re: a=[ lambda t: t**n for n in range(4) ]
Mage wrote: Scott David Daniels wrote: See, the body of your anonymous function just looks for "the current value of n" when it is _invoked_, not when it is _defined_. The "lambda functions" was an unclear part of the tutorial I read. Should I use them? Are they pythonic? As far I see they are good only for type less a bit. As for most python features which are not "dead obvious", you should only use them where they they make the code clearer than it would be without the use of that feature. In this case, I was responding to a particular use of lambda which, in fact, had a flaw that made the code do something different from what it looked like it was doing. I felt the distinction was clearer in the lambda form than it would have been with "def-style" function definitions. One of the reasons the distinction came out was that there was no confusing naming of "what this function means," only program structure. In a real program that is a hindrance. In the case of pointing out a flaw, it makes differences between two versions of some code more obvious. --Scott David Daniels [EMAIL PROTECTED] -- http://mail.python.org/mailman/listinfo/python-list
Re: a=[ lambda t: t**n for n in range(4) ]
Mage <[EMAIL PROTECTED]> wrote in news:mailman.2339.1114242211.1799.python- > The "lambda functions" was an unclear part of the tutorial I read. > Should I use them? Are they pythonic? > As far I see they are good only for type less a bit. And to obfusicate code. lambda is evil, do not play with it. Harald -- http://mail.python.org/mailman/listinfo/python-list
Re: PDF Printing support from Python
On 2005-04-23, Diez B. Roggisch <[EMAIL PROTECTED]> wrote: >> You're use of the word "driver" is one with which I'm not >> familiar. But I don't really "do windows" so it's probably a >> Widnowism. > > It could be that he means that creating PDFs on windows is > done using a fake printer that will produce the pdf when being > printed to - and that fake printer is implemented as a driver. > > And traditionally in printing one often speaks of printer > drivers - even if they are mere filters that can't be > considered drivers in the kernel driver way. I think it's the latter. I believe he wants to know how to print a PDF file without using any external programs (or "drivers") like Acrobat Reader or ghostscript that understand PDF. AFAIK, the only way to do what he wants would be for him to write a PDF engine in Python that renders PDF into whatever raw format is understood by his printer. -- Grant Edwards grante Yow! I'LL get it!! It's at probably a FEW of my visi.comITALIAN GIRL-FRIENDS!! -- http://mail.python.org/mailman/listinfo/python-list
Re: Python callbacks & PyGILState_Release()
Thomas Heller:
|> Python -> C++ -> Python Callback
|>
|> (example attached) an exception raised in the callback doesn't make it back
|> across C++ to Python.
...
|> void callback_wrapper( void *user_data )
|> {
|> // Acquire interpreter lock
|> PyGILState_STATE gstate = PyGILState_Ensure();
|> ...
|> // Call Python
|> pyresult = PyEval_CallObject( pyfunc, pyargs );
|> ...
|
|if (pyresult == NULL)
|PyErr_Print();
|
|> // Free interpreter lock
|> PyGILState_Release(gstate);
|> }
|
|PyErr_Print() will do the 'right' thing?s.
Thanks for the reply. However, this won't:
a) Stop the main Python script, and
b) Print the full stack trace (including Python and C++ SWIG wrapper)
Is there a clean way to save the full exception state in the callback
before the PyGILState_Release(), and restore it when we return across the
C++ wrapper?
If I knew what the proper "save" and "restore" exception state code bits
were, I could easily implement this with exception typemaps in SWIG.
Thanks,
Randall
P.S. Perhaps PyGILState_Release should take an argument instructing it to
exclude exception state when resetting the interpreter state back to its
original state.
--
http://mail.python.org/mailman/listinfo/python-list
Re: Python or PHP?
Lad wrote: >Is anyone capable of providing Python advantages over PHP if there are >any? > > I am also new to python but I use php for 4 years. I can tell: - python is more *pythonic* than php - python has its own perfume http://www.1976.com.tw/image/trussardi_python_uomo.jpg and it's nice. php doesn't have any smell - writing python programs you feel much better check this: http://wiki.w4py.org/pythonvsphp.html Mage -- http://mail.python.org/mailman/listinfo/python-list
