Re: Decorators (was: Re: I love assert)
Mayank, Thanks. I have only been using Python for about four years, so there are features I have only recently discovered. Decorators are one of them. So far, I encounter other Python users who are also unfamiliar with them. When I discovered them, I instantly saw how they could be valuable. Richard Riehle, PhD Core Faculty, ITU On Fri, Nov 14, 2014 at 6:36 PM, Mayank Tripathi wrote: > Decorators were there in Python 2.4, released in 2005. Not exactly new. > > On Sat Nov 15 2014 at 7:51:11 AM Richard Riehle wrote: > >> On Friday, November 14, 2014 2:18:48 PM UTC-8, Marko Rauhamaa wrote: >> > Richard Riehle : >> > >> > > I find that not a lot of Python user really appreciate the power of >> > > decorators. >> > >> > Well, I don't. >> > >> > All it means is that I've never seen a use of decorators that has >> > enhanced the code. Once I "see the light," I'll have no problem changing >> > my view. >> > >> > >> > Marko >> >> Decorators are new in Python, so there are not a lot of people using >> them. From my experience with other languages, especially Ada and Eiffel, >> I enjoy the benefit of assertions (as pre-conditions and post-conditions >> and invariants) at the specification level (not embedded in the code), so >> decorators are closer to my other experience. They bring me closer to the >> Design by Contract model of Ada and Eiffel. That is why I was so pleased >> to see them added to Python. >> >> It is true, however, that they are not immediately intutive in Python, >> but once understood, they are handy IMHO for improving code reliability. >> Perhaps I was spoiled by having this capability in some other languages. >> -- >> https://mail.python.org/mailman/listinfo/python-list >> > -- https://mail.python.org/mailman/listinfo/python-list
Re: Decorators
Tim Chase : > And decorators are used pretty regularly in just about every code-base > that I've touched (I've been programming in Python since early 2004, > so I've maintained pre-2.4 code without decorators and then brought it > forward to 2.4 where decorators were usable). Funny. My experience with Python is about as old, and I have yet to encounter them in code. I have seen (maybe even used) @staticmethod once or twice over a decade and then as a magic keyword rather than a "decorator pattern." Marko -- https://mail.python.org/mailman/listinfo/python-list
Re: Efficient Threading
On 14Nov2014 18:42, Empty Account wrote: I am thinking about writing a load test tool in Python, so I am interested in how I can create the most concurrent threads/processes with the fewest OS resources. I would imagine that I/O would need to be non-blocking. There are a number of options including standard library threading, gevent, stackless python, cython parallelism etc. Because I am new to Python, I am unsure on which libraries to choose. I am not really bothered on the tool chain, just as long as it is Python related (so I'd use PyPy for example). The locust.io load test tool uses gevent and seems to like it. I do not know enough to make a recommendation myself, but I believe they use it for the same reasons you have. Cheers, Cameron Simpson Whatever is not nailed down is mine. What I can pry loose is not nailed down. - Collis P. Huntingdon -- https://mail.python.org/mailman/listinfo/python-list
Re: Question about installing python and modules on Red Hat Linux 6
On 14Nov2014 19:01, pythonista wrote: I am developing a python application as a contractor. I would like to know if someone can provide me with some insight into the problems that then infrastructure team has been having. The scope of the project was to install python 2.7.8 and 4 modules/site packages on a fresh linux build. The first team failed after almost 3 weeks of work. Then they put their star Linux administrator on the task and it took almost a week of considerable effort. I was able to perform the same task on my windows desktop in less than a morning. I cannot get a straight answer as to what the problems are. They just seemed to be building and rebuilding all of the components from scratch. Can anyone provide me with insight as to the scope what the problem could have been? It depends. If they were trying to interoperate with the vendor supplied Python, they could be fighting with the RPM system. When I do this these days I do two things: - fetch and build Python 2.7.8 from source, to install in /usr/local/python-2.7.8 (i.e. use that as the --prefix option for configure). At this point you could just proceed and use that python, installing inside its site-packages as usual. Or you could go a little further and make a virtualenv for your project: - fetch virtualenv and (blasphemy!) install it in the vendor space using: "python setup.py install" - create a virtualenv for your project: "/usr/local/python-2.7.8/bin/python2.7 virtualenv.py /usr/local/venv-2.7.8-your-project-name" At that point you will have a "bin" directory inside /usr/local/venv-2.7.8-your-project-name with "python" and so forth. Executing that "python" runs the python-2.7.8 you built earlier but with all the system paths set to install and use the lib tree inside the virtualenv directory. The nice thing about that is that it is easy to make multiple virtualenvs, using distinct collections of additional packages, nicely isolated and easy to invoke (just run the "python" from within the appropriate virtualenv tree). Cheers, Cameron Simpson I just kept it wide-open thinking it would correct itself. Then I ran out of talent. - C. Fittipaldi -- https://mail.python.org/mailman/listinfo/python-list
Re: Question about installing python and modules on Red Hat Linux 6
On Sat, Nov 15, 2014 at 2:01 PM, pythonista wrote: > The scope of the project was to install python 2.7.8 and 4 modules/site > packages on a fresh linux build. > > The first team failed after almost 3 weeks of work. > > Then they put their star Linux administrator on the task and it took almost > a week of considerable effort. > > I was able to perform the same task on my windows desktop in less than a > morning. > > I cannot get a straight answer as to what the problems are. Well, you're asking the wrong people. The crystal ball manufacturer around here is horribly shoddy, shipping us faulty optics and devices with frequent outages. But if you ask the people who did the work, they should be able to tell you what was happening. My suspicion here is that the admins were trying to use multiple different installation methods, and they ran into issues. This currently can't happen on Windows, as there simply isn't a system-provided package manager (though that may be changing - soon Windows people will have all the same advantages AND disadvantages that everyone else has!), hence you perhaps found it easier. On my Debian systems, I can use "apt-get install python python-bs4 python-django" and grab a consistent set of packages from the OS-provided repositories; or alternatively, I can use pip to get things from the Python-provided repository (PyPI). Trying to use both can cause issues. Want an easy solution? Get a recent Python (preferably 3.x, but otherwise the latest builds of 2.7 should do I think), get pip, get virtualenv, and then do everything inside a venv with "pip install" (maybe using requirements.txt to save you the hassle of keying everything in). You'll find that that "just works", pretty much all the time. It's perhaps more work than you truly need (I personally don't usually bother with a venv), but that way you can be sure you're not trampling all over anything else. ChrisA -- https://mail.python.org/mailman/listinfo/python-list
Re: Decorators (was: Re: I love assert)
On 2014-11-14 18:19, Richard Riehle wrote: > Decorators are new in Python, so there are not a lot of people > using them. Um...they were introduced in 2.4 which was released in late 2004. So they've only been around for about (almost exactly) a decade. Not sure that qualifies as "new in Python". And decorators are used pretty regularly in just about every code-base that I've touched (I've been programming in Python since early 2004, so I've maintained pre-2.4 code without decorators and then brought it forward to 2.4 where decorators were usable). -tkc -- https://mail.python.org/mailman/listinfo/python-list
Re: I love assert
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 On 11/14/2014 06:58 PM, Steven D'Aprano wrote: > Ethan Furman wrote: >> >> My point being: a safety net that is so easily disabled does not count >> (IMHO) as a backup. > > Assertions are not a backup or a safety net. [...] Would you be happier if I phrased that as: Defensive programming techniques that can be unknowingly disabled by the end-user aren't very helpful? >>> If your process is so poor that you release code without running it with >>> asserts enabled, then assert will not >>> save you from bugs. >> >> This is one my very few complaints about Python: running it normally is the >> same as running with DEBUG turned >> on, so the unusual case is remembering to run with asserts turned /off/. > > That's curious. Your complaint is that asserts are too easy to disable, > nevertheless it takes a deliberate and > conscious act to disable them. And more likely they were disabled because somebody was trying to get more performance from the app, not because that someone thought, "I know, I'll turn asserts off and see how badly I can corrupt all my data." > By default, Python runs assertions. And yet that is your complaint, so I > suppose that you would rather asserts > *didn't* run by default and you needed a deliberate act to run in debug mode. That is correct. > That doesn't seem consistent to me. Because debug mode runs by default, many folks (myself included) simply run everything in debug mode. I have never even considered, until this very moment, to run my unittests with -O. And yet the very purpose of -O is to (hopefully) get more performance. So you end up with folks using asserts inappropriately, yet their tests pass. They distribute their code. Somebody has a slower machine, or gobs of data, so they decide to use -O. Asserts are disabled, something somewhere isn't checked, an error passes silently, the wrong thing happens... I'll you use your imagination for what happens next. Having debug mode be the default makes it too easy to screw up. And yes, I am aware of at least one very large, complex, and modular system that uses Python, Javascript, CSS, HTML, and some templating language I don't remember the name of. It allows for third-party module integration. It checks third-party code with asserts. It checks user-input with asserts. I strongly suspect that if debug mode was not the default, this particular abuse wouldn't happen nearly as frequently as it does. - -- ~Ethan~ -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.11 (GNU/Linux) iQIcBAEBAgAGBQJUZtIBAAoJENZ7D1rrH75NmJAP/jmW9GhlR2TeThlUoiIaslVU qKgiUeNplab9rbbIfQigmZaSTh/n+CeSK9pCu5dIOz7m6oBGoqtWJGFIl+E7pAsz +MWLCDCIzCi4AGslDZ3ZZSW+e1zG2EK2BgNtLuh3EV4fBJq9GSNDfzlsUbXO7qnQ yO0h41QuFOMuPiXDGkZ979u5OOBoH1JRUjmXhfUOSua0YcJ1dyRxNJKyhsMyUYPn relMcTyT04rXj/sl3LUFgaO898mV7ieKgB5tBybAg5EKpArzpnAeIgMjcTP8B6YH f+2n0jyL56oCCA0CO4BWP31unD8v89hBBeVJo0weprS9owq8OAdfyjXdfYMM77sM oeQjCM8rs7uej17l4joGfvkrAnsa1BQLyhWzk0aeH4xpfMkgLHVnbwRt6v2PvPWK IxNraSQQm3UjL1o1trLVznxT2+TOnNUucAl0XSLWSnIo9H1NJmYBZdHpmXvfo7R5 qIo1MyrQYLful+iaNI1I+5A3KLrKOduHm6Uqf4mDKXX6hMMbOdT1lHHpuD/fJYWW jNqOiMpZl3NtxuEJjdLc5mvXvkoTZ9Z188WfFvFNnsL27aGxFfuulAWKc6EpbWgW +8VoXVVhgs1mcB4UHM5dFrRSG7CgZi+btfHEGympWv74zun9FHHu2hNg+XPDibtS D5P2/nCwQYFuCgapy+Ko =QH9H -END PGP SIGNATURE- -- https://mail.python.org/mailman/listinfo/python-list
Re: fileno() not supported in Python 3.1
On 14Nov2014 09:51, Ian Kelly wrote: On Fri, Nov 14, 2014 at 12:36 AM, Cameron Simpson wrote: On 13Nov2014 15:48, satishmlm...@gmail.com wrote: import sys for stream in (sys.stdin, sys.stdout, sys.stderr): print(stream.fileno()) io.UnsupportedOperation: fileno Is there a workaround? The first workaround that suggests itself it to use a more modern Python. I've got 3.4.2 here, and it goes: [... works just fine ...] Why do you think the Python version has anything to do with it? Python 2.7.6 (default, Mar 22 2014, 22:59:56) [... works just fine ...] Clearly, in 2.7.6 it also "just works". Yeah, true. I think the consensus is now that the OP is using some kind of IDE where the IO streams are not connected to terminals or other real OS-level files, but to stream abstractions delivering the the IDE display widgetry. Thus no .fileno() facility, because there is no OS-level file. But we have yet to obtain that information from the OP. Cheers, Cameron Simpson That's about as good as when one of my students left me a note signed 'anon.'--written on personalized stationery. - Ayse Sercan -- https://mail.python.org/mailman/listinfo/python-list
Question about installing python and modules on Red Hat Linux 6
I am developing a python application as a contractor. I would like to know if someone can provide me with some insight into the problems that then infrastructure team has been having. The scope of the project was to install python 2.7.8 and 4 modules/site packages on a fresh linux build. The first team failed after almost 3 weeks of work. Then they put their star Linux administrator on the task and it took almost a week of considerable effort. I was able to perform the same task on my windows desktop in less than a morning. I cannot get a straight answer as to what the problems are. They just seemed to be building and rebuilding all of the components from scratch. Can anyone provide me with insight as to the scope what the problem could have been? Thanks -- https://mail.python.org/mailman/listinfo/python-list
Re: I love assert
Ethan Furman wrote: > -BEGIN PGP SIGNED MESSAGE- > Hash: SHA1 > > On 11/14/2014 03:33 AM, Steven D'Aprano wrote: >> >> I agree with Marko in this case. Marko's example of defensive programming >> is very similar to the one I gave in my essay here: >> >> http://import-that.dreamwidth.org/676.html >> >> You're correct of course that under the circumstances you describe the >> code will fail. But that is no different from the scenario: >> >> "a new status is added, the code is not modified to handle it, no tests >> are written to check the code is correct (or if the tests are written, >> the test suite is not run), and then the code is released at which point >> it fails" > > I am reminded of a Star Treck episode (Deep Space 9?) in which a Klingon > is mocking the Federation tech for having three backups, instead of only > two, to which the Federation tech replies, "When the second one fails, I > wouldn't want to be without my tertiary backup!" > > My point being: a safety net that is so easily disabled does not count > (IMHO) as a backup. Assertions are not a backup or a safety net. They are development tools, like functional requirements, unit tests, code review and the use of version control. Like any tool, you need to use it correctly. Writing assertions but never actually running them is not correct use of assertions, just like writing tests but never actually running them is not correct use of tests. One wouldn't say that code review by a senior developer before code is checked into the main branch is pointless because "if the developer doesn't perform the review, buggy code might be checked in". Well duh. >> If your process is so poor that you release code without running it with >> asserts enabled, then assert will not save you from bugs. > > This is one my very few complaints about Python: running it normally is > the same as running with DEBUG turned on, so the unusual case is > remembering to run with asserts turned /off/. That's curious. Your complaint is that asserts are too easy to disable, nevertheless it takes a deliberate and conscious act to disable them. By default, Python runs assertions. And yet that is your complaint, so I suppose that you would rather asserts *didn't* run by default and you needed a deliberate act to run in debug mode. That doesn't seem consistent to me. >> Assertions are just a tool, not a panacea. > > Right -- and using it is like using a rock when what you need is a > ball-peen hammer. ;) Compared to Eiffel, Python doesn't have a lot of flexibility to assertions. You either run them all, or you run none of them. But the assertions themselves can be as narrow or as broad as you like. It's just code, you can do anything you like in it. -- Steven -- https://mail.python.org/mailman/listinfo/python-list
Re: Decorators (was: Re: I love assert)
Decorators were there in Python 2.4, released in 2005. Not exactly new. On Sat Nov 15 2014 at 7:51:11 AM Richard Riehle wrote: > On Friday, November 14, 2014 2:18:48 PM UTC-8, Marko Rauhamaa wrote: > > Richard Riehle : > > > > > I find that not a lot of Python user really appreciate the power of > > > decorators. > > > > Well, I don't. > > > > All it means is that I've never seen a use of decorators that has > > enhanced the code. Once I "see the light," I'll have no problem changing > > my view. > > > > > > Marko > > Decorators are new in Python, so there are not a lot of people using > them. From my experience with other languages, especially Ada and Eiffel, > I enjoy the benefit of assertions (as pre-conditions and post-conditions > and invariants) at the specification level (not embedded in the code), so > decorators are closer to my other experience. They bring me closer to the > Design by Contract model of Ada and Eiffel. That is why I was so pleased > to see them added to Python. > > It is true, however, that they are not immediately intutive in Python, but > once understood, they are handy IMHO for improving code reliability. > Perhaps I was spoiled by having this capability in some other languages. > -- > https://mail.python.org/mailman/listinfo/python-list > -- https://mail.python.org/mailman/listinfo/python-list
Re: Decorators (was: Re: I love assert)
On Friday, November 14, 2014 2:18:48 PM UTC-8, Marko Rauhamaa wrote: > Richard Riehle : > > > I find that not a lot of Python user really appreciate the power of > > decorators. > > Well, I don't. > > All it means is that I've never seen a use of decorators that has > enhanced the code. Once I "see the light," I'll have no problem changing > my view. > > > Marko Decorators are new in Python, so there are not a lot of people using them. From my experience with other languages, especially Ada and Eiffel, I enjoy the benefit of assertions (as pre-conditions and post-conditions and invariants) at the specification level (not embedded in the code), so decorators are closer to my other experience. They bring me closer to the Design by Contract model of Ada and Eiffel. That is why I was so pleased to see them added to Python. It is true, however, that they are not immediately intutive in Python, but once understood, they are handy IMHO for improving code reliability. Perhaps I was spoiled by having this capability in some other languages. -- https://mail.python.org/mailman/listinfo/python-list
Re: I love assert
On Sat, Nov 15, 2014 at 1:14 PM, Tim Chase wrote: > On 2014-11-15 12:48, Chris Angelico wrote: >> conn = establish_database_connection() >> try: >> do_stuff() >> finally: >> conn.rollback() > > this sounds suspiciously like you'd never actually commit. Do you > mean something like > > conn = establisth_database_connection() > try: > do_stuff(conn) > except: > conn.rollback() > raise No; I prefer to have the commit be as close as possible to the code that needs it done. So in this toy example, the commit would be inside - maybe deep inside - do_stuff(). After committing, rolling back wouldn't hurt. ChrisA -- https://mail.python.org/mailman/listinfo/python-list
Re: I love assert
On 2014-11-15 12:48, Chris Angelico wrote: > conn = establish_database_connection() > try: > do_stuff() > finally: > conn.rollback() this sounds suspiciously like you'd never actually commit. Do you mean something like conn = establisth_database_connection() try: do_stuff(conn) except: conn.rollback() raise instead? I don't generally like bare excepts, but in this case, the exception just gets re-raised, so I feel Less Bad™ about it (there's still the case where the rollback call raises some alternate exception, obfuscating the underlying root issue). -tkc -- https://mail.python.org/mailman/listinfo/python-list
Re: I love assert
On Sat, Nov 15, 2014 at 12:30 PM, Marko Rauhamaa wrote: > Chris Angelico : > >> On Sat, Nov 15, 2014 at 11:12 AM, Marko Rauhamaa wrote: >>> Most importantly, assertion failures are not supposed to be recovered >>> from (within the program). Assertion failures can result in the loss >>> of life and limb. They can result in database corruption. They can >>> result in monetary losses. They can result in smoke coming out of the >>> monitor. >> >> Or, in theory, AssertionError just prevented any of the above from >> happening. > > I'd advice against catching AssertionError and trying to recover from it > within the program. You could catch it, log it and reraise it, but since > the failure modes could be completely unexpected (really, by > definition), I would move fault-tolerance outside the failing process > and try to restore a coherent reality from there. I agree - never catch it. But you should be able to prevent database corruption: conn = establish_database_connection() try: do_stuff() finally: conn.rollback() The raising of AssertionError anywhere inside do_stuff() will prevent craziness from getting to the database, because it aborts the execution. (You know, the way a royal pardon does.) ChrisA -- https://mail.python.org/mailman/listinfo/python-list
Re: I love assert
Chris Angelico : > On Sat, Nov 15, 2014 at 11:12 AM, Marko Rauhamaa wrote: >> Most importantly, assertion failures are not supposed to be recovered >> from (within the program). Assertion failures can result in the loss >> of life and limb. They can result in database corruption. They can >> result in monetary losses. They can result in smoke coming out of the >> monitor. > > Or, in theory, AssertionError just prevented any of the above from > happening. I'd advice against catching AssertionError and trying to recover from it within the program. You could catch it, log it and reraise it, but since the failure modes could be completely unexpected (really, by definition), I would move fault-tolerance outside the failing process and try to restore a coherent reality from there. Assertion errors are in the same class with CPython bugs, external signals (say, SIGKILL), security breaches, hardware failures and the like. For expected failure modes, other exceptions are a suitable facility. Marko -- https://mail.python.org/mailman/listinfo/python-list
Re: I love assert
On Sat, Nov 15, 2014 at 11:12 AM, Marko Rauhamaa wrote: > Most importantly, assertion failures are not supposed to be recovered > from (within the program). Assertion failures can result in the loss of > life and limb. They can result in database corruption. They can result > in monetary losses. They can result in smoke coming out of the monitor. Or, in theory, AssertionError just prevented any of the above from happening. ChrisA -- https://mail.python.org/mailman/listinfo/python-list
Re: I love assert
Steven D'Aprano : > Marko Rauhamaa wrote: > >> Asserts are not about notification, checking or optimization. They are >> about communicating what's going on in the programmer's mind. They are >> comments. > > Assertions can be used for *all of these things*. > > Assertions can be used for: > > - checking internal program logic; > - testing pre- and post-conditions; > - testing program invariants; > - comments which are verified at runtime; Most importantly, assertion failures are not supposed to be recovered from (within the program). Assertion failures can result in the loss of life and limb. They can result in database corruption. They can result in monetary losses. They can result in smoke coming out of the monitor. That's because the programmer is in no way prepared for the assertion to fail and cannot rely on the assertions to really be checked. IOW, assertions are not a mechanism for fault-tolerant programming. Marko -- https://mail.python.org/mailman/listinfo/python-list
Re: Array of Functions
On 11/14/2014 5:17 PM, Richard Riehle wrote: In C, C++, Ada, and functional languages, I can create an array of functions, albeit with the nastiness of pointers in the C family. For example, an array of functions where each function is an active button, or an array of functions that behave like formulae in a spreadsheet. Googling 'python spreadsheet', the first hit is https://manns.github.io/pyspread/ "Pyspread expects Python expressions in its grid cells," and expressions can reference other cells. There may be other relevant programs. I am finding this a bit challenging in Python. Since python functions are objects, they easy fit into any array of objects. They can also be the values in dicts. Since strings can be passed to built-in runtime compile, eval, and exec functions, (not part of standard C), functions can also be represented by a return expression, as in Pyspread, or even quoted def statements. A program that executes user-entered code is much easier in Python than in C or any other language where one would have to write or find lexer, parser, compiler, and execution functions. I think my difficulty is related to the REPL nature of Python. I do not understand this. The interpreter runs a REPL in interactive mode but can also run in batch mode. -- Terry Jan Reedy -- https://mail.python.org/mailman/listinfo/python-list
Re: I love assert
Marko Rauhamaa wrote:
> Asserts are not about notification, checking or optimization. They are
> about communicating what's going on in the programmer's mind. They are
> comments.
Assertions can be used for *all of these things*.
Assertions can be used for:
- checking internal program logic;
- testing pre- and post-conditions;
- testing program invariants;
- comments which are verified at runtime;
> So why use asserts instead of comments?
Not all comments can be replaced with an assertion, but some can:
# once we reach here, mylist has at least two items
is better turned into an assert:
assert len(mylist) >= 2
To someone who is fluent in Python, the assertion is as easy to read and
understandable as the English comment. And it has the added benefit that
the interpreter will verify that the comment is correct at runtime.
Verifying comments is important, since programmers are notorious for
ignoring comments and failing to update them:
http://import-that.dreamwidth.org/956.html
Why would you choose a comment rather than an assertion? If the code is
performance critical, and the extra cost of the assertion is significant,
and you cannot reasonably run the code using -O to disable it, then a
comment might be better.
> Asserts *could* help in fixing bugs:
>
> 1. An assertion failure immediately, unambiguously, declares even to
> customer service representatives that this is a terrible bug and
> should be brought to R&D's attention instead of hazing the poor
> customer with standard questions ("have you updated?", "have you
> rebooted?").
If only that were the case :-(
> 2. An assertion failure probably gives the developer an very good clue
> as to what has gone wrong. There is a good chance of quickly
> finding an accurate analysis and fix to the bug.
In general, it is desirable to have any eventual exception occur as soon as
possible to the ultimate cause of the exception. Assertions can aid in
that. Languages such as Eiffel provide a rich and powerful set of different
assertions, including:
require
ensure
check
debug
invariant
The Eiffel manual is explicit about the correct use of assertions:
It should be clear from the preceding discussion that contracts
are not a mechanism to test for special conditions, for example
erroneous user input. For that purpose, the usual control
structures ( if deposit_sum > 0 then ...) are available,
complemented in applicable cases by the exception handling
mechanism reviewed next. An assertion is instead a correctness
condition governing the relationship between two software modules
(not a software module and a human, or a software module and an
external device). If sum is negative on entry to deposit,
violating the precondition, the culprit is some other software
element, whose author was not careful enough to observe the terms
of the deal. Bluntly:
Rule -- Assertion Violation: A run-time assertion violation is
the manifestation of a bug.
[...]
That violations indicate bugs explains why it is legitimate to
enable or disable assertion monitoring through mere compilation
options: for a correct system -- one without bugs -- assertions
will always hold, so the compilation option makes no difference
to the semantics of the system.
https://docs.eiffel.com/book/method/et-design-contract-tm-assertions-and-exceptions
--
Steven
--
https://mail.python.org/mailman/listinfo/python-list
Re: Array of Functions
On 2014-11-14 22:17, Richard Riehle wrote:
In C, C++, Ada, and functional languages, I can create an array of
functions, albeit with the nastiness of pointers in the C family.
For example, an array of functions where each function is an active
button, or an array of functions that behave like formulae in a
spreadsheet. I am finding this a bit challenging in Python.
Example:
r1c1 r1c2 r1c3
r2c1 r2c2 r2c3
r3c1 r3c2 r3c3
where r1 is row 1 and c1 is column 1. Suppose I want an array where
the colum three is a set of functions that operates on the other two
columns, depending on the values I set for those rows and columns?
As noted, I can do this pretty easily in most languages (well, except
for Java which does not support any kind of functional programming
capability), even if I have to use pointers.
I think my difficulty is related to the REPL nature of Python.
However, I am sure some clever Pythonista has found a way to do
this.
Thanks in advance for any suggestions,
In C, you're not creating an array of functions, but an array of
_pointers_ to functions.
In Python, we don't have pointers, but we do have references.
For example, you can define a function:
>>> def my_func():
... print('my_func called')
...
The name of the function is just a reference to that function:
>>> print(my_func)
You call it using (...):
>>> my_func()
my_func called
You can store the reference in a list or bind another name to it:
>>> func_by_another_name = my_func
And call it by that other name:
>>> func_by_another_name()
my_func called
Does that help?
--
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Re: Array of Functions
On Fri, Nov 14, 2014 at 3:17 PM, Richard Riehle wrote: > In C, C++, Ada, and functional languages, I can create an array of functions, > albeit with the nastiness of pointers in the C family. For example, an > array of functions where each function is an active button, or an array of > functions that behave like formulae in a spreadsheet. I am finding this a > bit challenging in Python. > > Example: > > r1c1 r1c2 r1c3 > r2c1 r2c2 r2c3 > r3c1 r3c2 r3c3 > > where r1 is row 1 and c1 is column 1. Suppose I want an array where the > colum three is a set of functions that operates on the other two columns, > depending on the values I set for those rows and columns?As noted, I can > do this pretty easily in most languages (well, except for Java which does not > support any kind of functional programming capability), even if I have to use > pointers. > > I think my difficulty is related to the REPL nature of Python. However, I am > sure some clever Pythonista has found a way to do this. >>> list_of_functions = [lambda x=x: x + 4 for x in range(3)] >>> list_of_functions[0]() 4 >>> list_of_functions[1]() 5 >>> list_of_functions[2]() 6 If you want more help, you'll have to be more specific about the problem you're encountering. Since you didn't go into any detail, I'm just going to assume that it's the common pitfall of variable scoping in functions defined in a loop and point you to this FAQ answer: https://docs.python.org/3/faq/programming.html#why-do-lambdas-defined-in-a-loop-with-different-values-all-return-the-same-result -- https://mail.python.org/mailman/listinfo/python-list
Re: Decorators
Mark Lawrence : > Perhaps this helps > http://blog.dscpl.com.au/2014/01/how-you-implemented-your-python.html ? Thanks, but sorry, it didn't. I couldn't even relate to the supposed WSGI craze. I'm yet to face the situation where a colleague would point out, "See how elegantly you could have done that using a decorator." Marko -- https://mail.python.org/mailman/listinfo/python-list
Re: Array of Functions
I second the call for a more concrete implementation, but if you want the results of the functions in c3 to be responsive to the values of c1 and c2 (i.e., if you change r1c1, r1c3 returns a different value), it might be worth encapsulating the whole thing in an object and making the c3 functions properties, which is Python for 'preprocessed attributes.' On Friday, November 14, 2014 5:17:38 PM UTC-5, Richard Riehle wrote: > In C, C++, Ada, and functional languages, I can create an array of functions, > albeit with the nastiness of pointers in the C family. For example, an > array of functions where each function is an active button, or an array of > functions that behave like formulae in a spreadsheet. I am finding this a > bit challenging in Python. > > Example: > > r1c1 r1c2 r1c3 > r2c1 r2c2 r2c3 > r3c1 r3c2 r3c3 > > where r1 is row 1 and c1 is column 1. Suppose I want an array where the > colum three is a set of functions that operates on the other two columns, > depending on the values I set for those rows and columns?As noted, I can > do this pretty easily in most languages (well, except for Java which does not > support any kind of functional programming capability), even if I have to use > pointers. > > I think my difficulty is related to the REPL nature of Python. However, I am > sure some clever Pythonista has found a way to do this. > > Thanks in advance for any suggestions, > > Richard Riehle, PhD, International Technological University, San Jose, CA -- https://mail.python.org/mailman/listinfo/python-list
Re: Decorators
On 14/11/2014 22:18, Marko Rauhamaa wrote: Richard Riehle : I find that not a lot of Python user really appreciate the power of decorators. Well, I don't. All it means is that I've never seen a use of decorators that has enhanced the code. Once I "see the light," I'll have no problem changing my view. Perhaps this helps http://blog.dscpl.com.au/2014/01/how-you-implemented-your-python.html ? -- My fellow Pythonistas, ask not what our language can do for you, ask what you can do for our language. Mark Lawrence -- https://mail.python.org/mailman/listinfo/python-list
Re: Array of Functions
Richard Riehle : > Example: > > r1c1 r1c2 r1c3 > r2c1 r2c2 r2c3 > r3c1 r3c2 r3c3 > > where r1 is row 1 and c1 is column 1. Suppose I want an array where the > colum three is a set of functions that operates on the other two > columns, depending on the values I set for those rows and columns? As > noted, I can do this pretty easily in most languages (well, except for > Java which does not support any kind of functional programming > capability), even if I have to use pointers. Show some code in, say, Scheme (which is among the most functional programming languages in existence), and we'll see how we could translate that into Python. Marko -- https://mail.python.org/mailman/listinfo/python-list
Decorators (was: Re: I love assert)
Richard Riehle : > I find that not a lot of Python user really appreciate the power of > decorators. Well, I don't. All it means is that I've never seen a use of decorators that has enhanced the code. Once I "see the light," I'll have no problem changing my view. Marko -- https://mail.python.org/mailman/listinfo/python-list
Array of Functions
In C, C++, Ada, and functional languages, I can create an array of functions, albeit with the nastiness of pointers in the C family. For example, an array of functions where each function is an active button, or an array of functions that behave like formulae in a spreadsheet. I am finding this a bit challenging in Python. Example: r1c1 r1c2 r1c3 r2c1 r2c2 r2c3 r3c1 r3c2 r3c3 where r1 is row 1 and c1 is column 1. Suppose I want an array where the colum three is a set of functions that operates on the other two columns, depending on the values I set for those rows and columns?As noted, I can do this pretty easily in most languages (well, except for Java which does not support any kind of functional programming capability), even if I have to use pointers. I think my difficulty is related to the REPL nature of Python. However, I am sure some clever Pythonista has found a way to do this. Thanks in advance for any suggestions, Richard Riehle, PhD, International Technological University, San Jose, CA -- https://mail.python.org/mailman/listinfo/python-list
Re: I love assert
On Tuesday, November 11, 2014 11:41:06 AM UTC-8, Peter Cacioppi wrote: > I get the impression that most Pythonistas aren't as habituated with assert > statements as I am. Is that just a misimpression on my part? If not, is there > a good reason to assert less with Python than other languages? > > As far as I can tell, Python supports assert perfectly well. When run with > the optimization flagging, the asserts are truly removed. > > I think one needs to take care with some basic assert coding - it's not a > substitute for unit tests, it doesn't absolve you of normal exception > responsibilities, and, most of all, it should be used for passive inspection > and not action. But given these guidelines, I still find it very useful as > "active comments". -- Reply & Comment: I am new to this group, but really like Python. One of the things I find helpful is to combine the assert with the decorator capability to produce code that is close to, although not identical to, the Design by Contract features built-in to Eiffel and Ada (2012). I find that not a lot of Python user really appreciate the power of decorators. Richard Riehle, PhD, International Technological University, San Jose, CA. -- https://mail.python.org/mailman/listinfo/python-list
Re: Two locations for module struct ?
On 11/14/2014 10:11 AM, ast wrote: Hello In module wave there is a sub module struct. struct is not a documented part of the wave module. You can call function pack() with: import wave val = wave.struct.pack(...) wave imports several other stdlib modules. All are accessible the same way. None are documented or included in wave.__all__. Some modules, typically more recently written or edited, do things like import struct as _struct to avoid such leakage of import. But this is a nuisance to write and read. Best to stick with the documented api. -- Terry Jan Reedy -- https://mail.python.org/mailman/listinfo/python-list
Re: I love assert
Ethan Furman : > Python the language is just the opposite: debug mode is on /by > default/, and to turn it off you have to specify -O: C's the same way. When I did Java, we enabled assertions in production code. Marko -- https://mail.python.org/mailman/listinfo/python-list
Re: I love assert
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 On 11/14/2014 11:12 AM, Marko Rauhamaa wrote: > Ethan Furman wrote: > >> My point being: a safety net that is so easily disabled does not count >> (IMHO) as a backup. > > Correct. You never lean on assertions. They are primarily formal comments. On this point we can agree. :) >> This is one my very few complaints about Python: running it normally is the >> same as running with DEBUG turned >> on, so the unusual case is remembering to run with asserts turned /off/. > > I don't remember ever having optimized them out in any programming language. > Has that really improved the > performance of your code? In the handful of languages I have worked with so far, it's the other way 'round: you un-optimize debug mode in. CPython itself is a good example: when configuring, you must add --with-pydebug in order to get all the extra checks added (which is great when adding new features), but that option isn't used when making production CPythons; yet Python the language is just the opposite: debug mode is on /by default/, and to turn it off you have to specify -O: $ ./python -c "print(__debug__)" True $ ./python -O -c "print(__debug__)" False - -- ~Ethan~ -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.11 (GNU/Linux) iQIcBAEBAgAGBQJUZmjlAAoJENZ7D1rrH75N3wMP/j9AowuuEvW9khTFX512QUHn VGwEqkIu4FDFRA8T+qzwqhL7st5GGsnXaPvaWCLmPGbtt1qrVxJ1M6LLkuSWI8Fj /hGe5rcEPP88/tMA5zy/pmg6jDgl96hojCnDmmS6meIQijVRpxMUGQ/4+N1oKI5d JYKOlhFStk0N5O6gyZ3Yc6UDY+I9kLVPZsIgH0bXx5IkvwQUi1aNboADehDgSbM5 XDCuZvfNsauKyJZL52NkKu6qLSY/CHDx4kaWdP/i75gZPeVJirjEUkcLYSK6iE19 DpkyeR5wetH1yppH27yyfZPCKHnaYD8O/rykRrQLaIYefKb7XhxGWXa4C17w+AQP 3+hjONiPBsXe2FZZNTskKufI88oXbFwTyI3GseeWTIbS+V9TIwGTjZA+V9jc6EvL T6T9PRGwOzfPolcLZ43x3ea8uCzLhxe0BILEfdmv6XPoPl9sJ5wHhbxg0oblo8GL GNkfOFw0ncxplyobU0RXhvsKCUg6EpAukWgIcX5IhHfnesoS1BpSMtZubAbY4GVI AHzL34KpYhOIDo3Ws26dCtHz5ocJSnDlHv2lxv+iEEZV+4lShFEreqfCLK0hcJTP QMFoI401Dy3bLd3wJX9mYQA+nMGhNtRK+4uYwGSbAinOGDKVuqrmNM7wCaF9lr/I aC+wno9PzNxkDNy2nUpY =gJhZ -END PGP SIGNATURE- -- https://mail.python.org/mailman/listinfo/python-list
Re: Help with Python Multiprocessing
On Thursday, November 13, 2014 3:22:49 PM UTC-8, Anurag wrote: > On Thursday, November 13, 2014 2:18:50 PM UTC-5, sohca...@gmail.com wrote: > > On Thursday, November 13, 2014 10:07:56 AM UTC-8, Anurag wrote: > > > I am having trouble understanding the Multiprocessing module. > > > I need to run three different files 'Worker1' , 'Worker2', 'Worker3' all > > > at once. Currently I am doing this : > > > > > > from multiprocessing import Process > > > > > > import Worker1.py > > > import Worker2.py > > > import Worker3.py > > > > > > > > > > > > p1 = Process(target=Worker1.py) > > > p1.start() > > > p2 = Process(target=Worker2.py) > > > p2.start() > > > p3 = Process(target=Worker3.py) > > > p3.start() > > > > > > But this will only start the 'Worker1'. How do I execute all the three > > > files at once? > > > > > > Thanks > > > > Do your WorkerX.py files have a main() function or anything like that? If > > not, they should. Then, you'd set the targets to WorkerX.main. > > My Worker files have three different functions What I mean is that your code should probably look more like this: # Contents of main.py from multiprocessing import Process import Worker1 import Worker2 import Worker3 p1 = Process(target=Worker1.main) p1.start() p2 = Process(target=Worker2.main) p2.start() p3 = Process(target=Worker3.main) p3.start # Contents of Worker1.py def main(): # Do worker1 stuff... # Contents of Worker2.py def main(): # Do worker2 stuff... # Contents of Worker3.py def main(): # Do worker3 stuff... Alternatively, you could have a single worker.py, import that, but have 3 main() functions, main1(), main2(), main3(), and set the targets for each process to those functions. Maybe its because I'm less experienced as most people on this group, but setting a Process's target to a module and not a specific function in that module seems slightly strange and ambiguous to me. -- https://mail.python.org/mailman/listinfo/python-list
Efficient Threading
Hi, I am thinking about writing a load test tool in Python, so I am interested in how I can create the most concurrent threads/processes with the fewest OS resources. I would imagine that I/O would need to be non-blocking. There are a number of options including standard library threading, gevent, stackless python, cython parallelism etc. Because I am new to Python, I am unsure on which libraries to choose. I am not really bothered on the tool chain, just as long as it is Python related (so I'd use PyPy for example). Many Thanks Aidy -- https://mail.python.org/mailman/listinfo/python-list
Re: I love assert
Ethan Furman : > My point being: a safety net that is so easily disabled does not count > (IMHO) as a backup. Correct. You never lean on assertions. They are primarily formal comments. However, assertion failures do help in troubleshooting occasionally. Most importantly, they immediately, unquestionably point the finger at the developer. > This is one my very few complaints about Python: running it normally > is the same as running with DEBUG turned on, so the unusual case is > remembering to run with asserts turned /off/. I don't remember ever having optimized them out in any programming language. Has that really improved the performance of your code? Marko -- https://mail.python.org/mailman/listinfo/python-list
Re: I love assert
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 On 11/14/2014 03:33 AM, Steven D'Aprano wrote: > > I agree with Marko in this case. Marko's example of defensive programming is > very similar to the one I gave in my > essay here: > > http://import-that.dreamwidth.org/676.html > > You're correct of course that under the circumstances you describe the code > will fail. But that is no different > from the scenario: > > "a new status is added, the code is not modified to handle it, no tests are > written to check the code is correct > (or if the tests are written, the test suite is not run), and then the code > is released at which point it fails" I am reminded of a Star Treck episode (Deep Space 9?) in which a Klingon is mocking the Federation tech for having three backups, instead of only two, to which the Federation tech replies, "When the second one fails, I wouldn't want to be without my tertiary backup!" My point being: a safety net that is so easily disabled does not count (IMHO) as a backup. > If your process is so poor that you release code without running it with > asserts enabled, then assert will not save > you from bugs. This is one my very few complaints about Python: running it normally is the same as running with DEBUG turned on, so the unusual case is remembering to run with asserts turned /off/. > Assertions are just a tool, not a panacea. Right -- and using it is like using a rock when what you need is a ball-peen hammer. ;) - -- ~Ethan~ -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.11 (GNU/Linux) iQIcBAEBAgAGBQJUZkdzAAoJENZ7D1rrH75Nl9YQALx9UIAxYzlzH04EoMlILErb 0wz5xNhTM2JmF3csJPi3pQSpEr1XpHhWjFZYsFoPB24I8bN7tGALb91+ME7ElHgw WP6Z+AVPuHCRxTG/oteK72+f5S+SN6zV1ECwrUuWxqIt5CHzYFtQjRKvEinNDtaT xKtEfYZdrZFeqo7ssV2gHprDd1QFIAygLMbIlwke6nT/TdMGmw/wG9LQtpfSnrQc 4BeFoeYM3OL+hxHUNfYJI9cGL7skykU3EHnuFqNbhA6QhGawvBqUhVDGoFFDkJ/e AX6AGk5Fu9cvjEFTzRQJzW4S5s6nD4dYM7Z93GfD9G9KBmfzQNM1pBA3yqxf0S8Q CWTWBs8pPkYe/G1Y/WOn7lzYQdMneIGUNnHR8fnABKPPf5IeTXabkWgtVnq1g5Ty DVcg/47G8gBMOTz5DD08iigu4f2bsNGowFoAkCDsbNmzjmxODGSUoj1ph/4xg6HP HbuEQZXwNZXmlP9ZcLoxjCKdBdRJo3JZ4hAf6kVj4VT4y438GL2dI0/KIUSDWgYE B0mCsQ7WYm80AvfpYR7fJoZsd/5jXe7RCLHanNLIZff3LupdFZri5E246KloUBj+ 3Jw3HgwME6wyDshiHtsS5tuDcANvow+PICA+wn2KmU9Mn2JNwsG3D98ZFJfXp0JR eG/Pg7cgQhrjhFqe6cgO =EoEX -END PGP SIGNATURE- -- https://mail.python.org/mailman/listinfo/python-list
Re: Two locations for module struct ?
"Peter Otten" <__pete...@web.de> a écrit dans le message de news:mailman.15823.1415983912.18130.python-l...@python.org... Do you see the pattern? You should ;) Understood thx -- https://mail.python.org/mailman/listinfo/python-list
Re: I love assert
On Fri, Nov 14, 2014 at 4:37 AM, Steven D'Aprano wrote: > Ethan Furman wrote: > >>> There's no way to make the CONFUSED status be handled without actually >>> changing the code. The difference is that this version will not >>> incorrectly treat CONFUSED as WARNING; it just won't do anything at >>> all if the code is optimized. >> >> So, a different wrong thing, but still a wrong thing. ;) > > And potentially a *worse* wrong thing. Potentially it's worse, but more likely doing the wrong thing will be worse than doing nothing. >"I find it amusing when novice programmers believe their main > job is preventing programs from crashing. ... More experienced > programmers realize that correct code is great, code that > crashes could use improvement, but incorrect code that doesn’t > crash is a horrible nightmare." > -- Chris Smith > > Assertions can help by this, by causing wrong code to fail as soon as > possible (provided, of course, that you don't defeat the assertions by > running the code with assertions disabled). I fail to see the relevance of this quote. The code I posted that you're responding to does use an assertion. The case where it does "a different wrong thing" is precisely the case where assertions are disabled. -- https://mail.python.org/mailman/listinfo/python-list
Re: fileno() not supported in Python 3.1
On Fri, Nov 14, 2014 at 12:36 AM, Cameron Simpson wrote: > On 13Nov2014 15:48, satishmlm...@gmail.com wrote: >> >> import sys >> for stream in (sys.stdin, sys.stdout, sys.stderr): >> print(stream.fileno()) >> >> >> io.UnsupportedOperation: fileno >> >> Is there a workaround? > > > The first workaround that suggests itself it to use a more modern Python. > I've got 3.4.2 here, and it goes: > >Python 3.4.2 (default, Nov 5 2014, 21:19:51) >[GCC 4.2.1 Compatible Apple LLVM 6.0 (clang-600.0.54)] on darwin >Type "help", "copyright", "credits" or "license" for more information. >>>> import sys >>>> for stream in (sys.stdin, sys.stdout, sys.stderr): >... print(stream.fileno()) >... >0 >1 >2 >>>> > > In short, in 3.4.2 it just works. Why do you think the Python version has anything to do with it? Python 2.7.6 (default, Mar 22 2014, 22:59:56) [GCC 4.8.2] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> import sys >>> for stream in (sys.stdin, sys.stdout, sys.stderr): ... print(stream.fileno()) ... 0 1 2 Clearly, in 2.7.6 it also "just works". -- https://mail.python.org/mailman/listinfo/python-list
Re: python on android: where to start
On 14/11/2014 2:18 pm, maurog wrote: I looked at the newsgroup, but I didn't find recent infos on this topic. On the other side I went lost by looking for this topic with google. So I'm asking you my question, if I want to develop or run some code with python on android, what are the resources to start with? PyQt4 or PyQt5 with pyqtdeploy... http://pyqt.sourceforge.net/Docs/pyqtdeploy/ Phil -- https://mail.python.org/mailman/listinfo/python-list
Re: Two locations for module struct ?
ast wrote: > In module wave there is a sub module struct. > You can call function pack() with: > > import wave > val = wave.struct.pack(...) > > but the same function can be called with: > > import struct > val = struct.pack(...) > > Is it exactly the same module in both location ? You can answer that yourself: >>> import struct, wave >>> struct is wave.struct True > Why putting struct in two places ? Assumming your code is part of a module called mymodule.py > import wave > val = wave.struct.pack(...) > import struct > val = struct.pack(...) you can now also do import mymodule val = mymodule.struct.pack(...) or even val = mymodule.wave.struct.pack(...) Do you see the pattern? You should ;) -- https://mail.python.org/mailman/listinfo/python-list
Re: Two locations for module struct ?
On Sat, Nov 15, 2014 at 2:11 AM, ast wrote: > In module wave there is a sub module struct. > You can call function pack() with: > > import wave > val = wave.struct.pack(...) > > but the same function can be called with: > > import struct > val = struct.pack(...) > > Is it exactly the same module in both location ? > Why putting struct in two places ? I don't think that's a submodule of wave. It's just the standard struct module, which presumably wave imported. Use it as struct, not as wave.struct. ChrisA -- https://mail.python.org/mailman/listinfo/python-list
Two locations for module struct ?
Hello In module wave there is a sub module struct. You can call function pack() with: import wave val = wave.struct.pack(...) but the same function can be called with: import struct val = struct.pack(...) Is it exactly the same module in both location ? Why putting struct in two places ? -- https://mail.python.org/mailman/listinfo/python-list
Re:python on android: where to start
maurog Wrote in message: > I looked at the newsgroup, but I didn't find recent infos on this topic. > On the other side I went lost by looking for this topic with google. So > I'm asking you my question, if I want to develop or run some code with > python on android, what are the resources to start with? > > Thanks > > mauro > My Google shows two useful sites on the first page. Qpython.com Kivy.org -- DaveA -- https://mail.python.org/mailman/listinfo/python-list
Re: python on android: where to start
You can try Kivy. http://kivy.org On Fri Nov 14 2014 at 7:51:08 PM maurog wrote: > I looked at the newsgroup, but I didn't find recent infos on this topic. > On the other side I went lost by looking for this topic with google. So > I'm asking you my question, if I want to develop or run some code with > python on android, what are the resources to start with? > > Thanks > > mauro > -- > https://mail.python.org/mailman/listinfo/python-list > -- https://mail.python.org/mailman/listinfo/python-list
python on android: where to start
I looked at the newsgroup, but I didn't find recent infos on this topic. On the other side I went lost by looking for this topic with google. So I'm asking you my question, if I want to develop or run some code with python on android, what are the resources to start with? Thanks mauro -- https://mail.python.org/mailman/listinfo/python-list
Authentication method with txjson-rpc.
Hi, I want to write authentication by txjson, Please help me in this way. -- https://mail.python.org/mailman/listinfo/python-list
Re: Twisted and txJSON-RPC
Hi, I want to write authentication with txjson-rpc. please guide me in this method! best Regards, Ali Hallaji -- https://mail.python.org/mailman/listinfo/python-list
Islam prohibited women to be Unveiled....why?
Islam prohibited women to be Unveiledwhy?
Are there any harmful effects on women if they used to display parts of their
body? Let us read.
According to the latest figures, the incidence of melanoma, a potentially fatal
skin cancer, is increasing dramatically. It is currently the most common type
of cancer in young women between the ages of 25 and 29.
Researchers believe that sun exposure plays a significant role in the
development of melanoma. According to Dr. Diane Berson, an American
dermatologist says "intense sun exposure prior to age 20 may be more of a
significant risk factor for skin cancer than sun exposure past the age of 20.
Three or more blistering sunburns early in life, or three or more years of
working out of doors, (e.g. camp counselors or lifeguards), without protection,
can increase the risk of skin cancer by more than three times."
Another study held from 1973 to 2004 found that the rate of new melanoma cases
in younger women had jumped 50 percent since 1980, but did not increase for
younger men in that period.
"It's worrying," said Mark Purdue, a research fellow at the National Cancer
Institute, who led the analysis published in the Journal of Investigative
Dermatology. "What we are seeing in young adults right now could foretell a
much larger number of melanoma cases in older women." he said.
"One possible explanation is increases among young women of recreational sun
exposure or tanning bed use," Purdue said. "Both of these things have been
identified as risk factors."
Statistics say that 62,000 melanoma cases are diagnosed each year in the United
States, and more than 8,400 people die from the disease, according to the
American Cancer Society. Previous studies have shown that the rate of new
diagnoses has been increasing among adults overall.
Woman's dress in Islam
According to religion of Islam woman should only display her face and palms of
hands in front of foreigner men (indoor and outdoor) and more than that is
prohibited.
Allah Almighty tells prophet Mohamed peace be upon him to order women to do the
following: (And tell the believing women to lower their gaze (from looking at
forbidden things), and protect their private parts (from illegal sexual acts)
and not to show off their adornment except only that which is apparent (like
both eyes for necessity to see the way, or outer palms of hands or one eye or
dress like veil, gloves, head-cover, apron, etc.), and to draw their veils all
over Juyûbihinna (i.e. their bodies, faces, necks and bosoms) and not to reveal
their adornment except to their husbands, or their fathers, or their husband's
fathers, or their sons, or their husband's sons, or their brothers or their
brother's sons, or their sister's sons, or their (Muslim) women (i.e. their
sisters in Islâm), or the (female) slaves whom their right hands possess, or
old male servants who lack vigour, or small children who have no sense of
feminine sex. And let them not stamp their feet so as to reveal what they hide
of their adornment. And all of you beg Allâh to forgive you all, O believers,
that you may be successful.){ Sûrat An-Nûr - The Light -verse31}.
Also prophet Mohamed peace be upon him says in the right Hadith about some
indications for the imminence of day of resurrection that "there will be women
who are dressed and naked at the same time, who are reeling while walking and
their heads are like the top of the camel, those will not enter the heaven or
even smell its smell" [narrated by Abu- horraira]
Muslim women who are veiled believe that their body is valuable so it should
not be as a commodity that is exposed to everyone to evaluate.
Conclusion
The great religion of Islam doesn't approve any practice that may cause any
harm to both men and women , therefore Allah Almighty and His prophet Mohamed
peace be upon him order women to be veiled because woman's veil definitely
respects woman than exposing her parts in front of everyone.
Also, Allah Almighty didn't order women to be veiled and ordered men to do what
they want but He Almighty orders men also to respect women by not to look in
their parts because that is purer for them so that Allah Almighty tells the
prophet to inform men to:(Tell the believing men to lower their gaze (from
looking at forbidden things), and protect their private parts (from illegal
sexual acts, etc.). That is purer for them. Verily, Allah is All-Aware of what
they do.){ Sûrat An-Nûr - The Light -verse30}.
--
By: Abduldaem Al-Kaheel
www.kaheel7.com/eng
http://www.kaheel7.com/eng/index.php/legislative-miracles/646-islam-prohibited-women-to-be-unveiledwhy
References:
*
http://www.webmd.com/skin-beauty/guide/sun-exposure-skin-cancer
*
http://www.boston.com/news/nation/washington/articles/2008/07/11/skin_cancer_on_rise_in_young_women/
* http://www.medicalnewstoday.com/article
Re: fileno() not supported in Python 3.1
On Fri, Nov 14, 2014 at 8:59 AM, Nobody wrote: > On Thu, 13 Nov 2014 15:48:32 -0800, satishmlmlml wrote: > >> import sys >> for stream in (sys.stdin, sys.stdout, sys.stderr): >>print(stream.fileno()) >> >> >> io.UnsupportedOperation: fileno >> >> Is there a workaround? > > Try: > sys.stdin.buffer.fileno() > > or maybe > > sys.stdin.buffer.raw.fileno() > > In Python 3.x, sys.stdin isn't actually a "file", it's a TextIOWrapper > around a BufferedReader around a file (io.FileIO). > > TextIOWrapper is responsible for converting a stream of bytes to a stream > of (Unicode) characters. BufferedReader is responsible for buffering (like > C stdio). > A little off topic, but why not upgrade to 3.4 if you are learning python. I run 2.7, but I've read that much has improved in the 3.x series since 3.1 > > -- > https://mail.python.org/mailman/listinfo/python-list -- Joel Goldstick http://joelgoldstick.com -- https://mail.python.org/mailman/listinfo/python-list
Re: fileno() not supported in Python 3.1
On Thu, 13 Nov 2014 15:48:32 -0800, satishmlmlml wrote: > import sys > for stream in (sys.stdin, sys.stdout, sys.stderr): >print(stream.fileno()) > > > io.UnsupportedOperation: fileno > > Is there a workaround? Try: sys.stdin.buffer.fileno() or maybe sys.stdin.buffer.raw.fileno() In Python 3.x, sys.stdin isn't actually a "file", it's a TextIOWrapper around a BufferedReader around a file (io.FileIO). TextIOWrapper is responsible for converting a stream of bytes to a stream of (Unicode) characters. BufferedReader is responsible for buffering (like C stdio). -- https://mail.python.org/mailman/listinfo/python-list
Re: Python 3.x (beazley): __context__ vs __cause__ attributes in exception handling
It's been answered here: http://stackoverflow.com/questions/26924045/python-3-x-beazley-context-vs- cause-attributes-in-exception-handling?noredirect=1#comment42403467_26924045 -- https://mail.python.org/mailman/listinfo/python-list
Re: UnicodeDecodeError: 'charmap' codec can't decode byte 0x81 in position 308: character maps to
On Fri, Nov 14, 2014 at 6:57 AM, wrote:
> For 'mimetypes' in the code given below, python is giving the following
> error. Kindly help.
>
import os
matches = []
for (dirname, dirshere, fileshere) in os.walk(r'C:\Python34'):
> for filename in fileshere:
> if filename.endswith('.py'):
> pathname = os.path.join(dirname, filename)
> if 'mimetypes' in open(pathname).read():
> matches.append(pathname)
>
>
> Traceback (most recent call last):
> File "", line 5, in
> if 'mimetypes' in open(pathname).read():
> File "C:\Python34\lib\encodings\cp1252.py", line 23, in decode
> return codecs.charmap_decode(input,self.errors,decoding_table)[0]
> UnicodeDecodeError: 'charmap' codec can't decode byte 0x81 in position 308:
> character maps to
You should understand encodings. There is lots of literature on the
web about unicode and python. In your case, the fact that you are
reading a file called cp1252.py and your code is raising a
UnicodeDecodeError should be a clue
> --
> https://mail.python.org/mailman/listinfo/python-list
--
Joel Goldstick
http://joelgoldstick.com
--
https://mail.python.org/mailman/listinfo/python-list
UnicodeDecodeError: 'charmap' codec can't decode byte 0x81 in position 308: character maps to
For 'mimetypes' in the code given below, python is giving the following error.
Kindly help.
>>> import os
>>> matches = []
>>> for (dirname, dirshere, fileshere) in os.walk(r'C:\Python34'):
for filename in fileshere:
if filename.endswith('.py'):
pathname = os.path.join(dirname, filename)
if 'mimetypes' in open(pathname).read():
matches.append(pathname)
Traceback (most recent call last):
File "", line 5, in
if 'mimetypes' in open(pathname).read():
File "C:\Python34\lib\encodings\cp1252.py", line 23, in decode
return codecs.charmap_decode(input,self.errors,decoding_table)[0]
UnicodeDecodeError: 'charmap' codec can't decode byte 0x81 in position 308:
character maps to
--
https://mail.python.org/mailman/listinfo/python-list
Re: I love assert
Ethan Furman wrote: >> There's no way to make the CONFUSED status be handled without actually >> changing the code. The difference is that this version will not >> incorrectly treat CONFUSED as WARNING; it just won't do anything at >> all if the code is optimized. > > So, a different wrong thing, but still a wrong thing. ;) And potentially a *worse* wrong thing. "I find it amusing when novice programmers believe their main job is preventing programs from crashing. ... More experienced programmers realize that correct code is great, code that crashes could use improvement, but incorrect code that doesn’t crash is a horrible nightmare." -- Chris Smith Assertions can help by this, by causing wrong code to fail as soon as possible (provided, of course, that you don't defeat the assertions by running the code with assertions disabled). -- Steven -- https://mail.python.org/mailman/listinfo/python-list
Re: io.UnsupportedOperation: fileno
Am 14.11.2014 00:42 schrieb satishmlm...@gmail.com: fileno() in not supported. Is it only in 3.1? What is the workaround? You have been asked many times about the details of your environment. Especially, you have been told that it is important to know if you directly use the Python CLI or some GUI like IDLE. I just tested the latter thing and found out that it indeed makes a difference, as it introduces a replacement for the std* stuff you are missing: >>> sys.stdin >>> sys.stdout >>> sys.stderr Calling .fileno() on such a Pseudo*File just raises an UnsupportedOperation exception. This is in contrast to using the CLI directly. -- https://mail.python.org/mailman/listinfo/python-list
Re: I love assert
Ethan Furman wrote: > On 11/12/2014 01:41 PM, Marko Rauhamaa wrote: >> >> Or I might indicate the exhaustion of possibilities: >> >> if status == OK: >> ... >> elif status == ERROR: >> ... >> else: >> assert status == WARNING >> ... > > And here's a nice example of what one should NOT do. Imagine that a new > status, CONFUSED is added, the above code is not modified to handle it, > and for whatever reason the program is being run optimized -- the assert > is not there, and CONFUSED is treated the same as WARNING. I agree with Marko in this case. Marko's example of defensive programming is very similar to the one I gave in my essay here: http://import-that.dreamwidth.org/676.html You're correct of course that under the circumstances you describe the code will fail. But that is no different from the scenario: "a new status is added, the code is not modified to handle it, no tests are written to check the code is correct (or if the tests are written, the test suite is not run), and then the code is released at which point it fails" We know that even the best programmer writes buggy code, which is why we invent processes like defensive programming, design by contract, test driven development, unit testing and so on. Even so, buggy code gets written and released. When that happens, it is a failure of process. If your process is so poor that you release code without running it with asserts enabled, then assert will not save you from bugs. No process is immune to sufficiently malicious or incompetent use. Assertions are just a tool, not a panacea. -- Steven -- https://mail.python.org/mailman/listinfo/python-list
Re: I love assert
Peter Cacioppi wrote: > I get the impression that most Pythonistas aren't as habituated with > assert statements as I am. Is that just a misimpression on my part? If > not, is there a good reason to assert less with Python than other > languages? I love assert, and use it frequently. But there are good reasons and bad reasons to use it. I've written an essay about the good reasons to use assert, e.g. defensive programming, program invariants, checked comments, design by contract, and when not to use them, e.g. testing arguments to public interfaces. http://import-that.dreamwidth.org/676.html > As far as I can tell, Python supports assert perfectly well. When run with > the optimization flagging, the asserts are truly removed. > > I think one needs to take care with some basic assert coding - it's not a > substitute for unit tests, it doesn't absolve you of normal exception > responsibilities, and, most of all, it should be used for passive > inspection and not action. But given these guidelines, I still find it > very useful as "active comments". Agreed completely! -- Steven -- https://mail.python.org/mailman/listinfo/python-list
Re: I don't read docs and don't know how to use Google. What does the print function do?
On Fri, Nov 14, 2014 at 9:58 PM, Steven D'Aprano wrote: > http://blog.codinghorror.com/why-cant-programmers-program/ > > Not everyone agrees that this is a thing: > > http://www.skorks.com/2010/10/99-out-of-100-programmers-cant-program-i-call-bullshit/ > > I'm inclined to accept that maybe 99 out of 100 *applications* for > programming jobs are from people who can't program, but I don't think that > 99 out of 100 *programmers* can't program. It's probably more like 65, > maybe 70 out of 100, tops. I was talking only about *applications* at that point. From the point of view of an applicant, the massive noise of incompetent people trying to get the job means it's really hard to get heard, especially since a lot of the incompetents can make their resumes look great. [1] So getting a job you apply for based on your own skill is... not easy. At least, I'm fairly sure it's not easy. All I know is that it's never happened to me. [1] They probably learned from all the other department heads. http://dilbert.com/strips/comic/2011-02-20/ ChrisA -- https://mail.python.org/mailman/listinfo/python-list
Re: What does zip mean?
Grant Edwards wrote: > What the zipper on a coat does is convert two separate sequences into > a single sequence where the members alternate between the two input > sequences. IOW if we want to do something analogous to a zipper > fastener it should do this: > > zip([a,b,c,d,e,f],[1,2,3,4,5,6]) => [a,1,b,2,c,3,d,4,e,5,f,6] While that is correct, the name "zip" for zip([a,b,c],[1,2,3]) => [(a,1), (b,2), (c,3)] is long-established. I generally call the alternate behaviour "interleaving" or "muxing", derived from multiplexer. While muxing and demuxing is extremely important in circuit design and telecommunications, I've never needed it in Python programming. -- Steven -- https://mail.python.org/mailman/listinfo/python-list
Re: I don't read docs and don't know how to use Google. What does the print function do?
Chris Angelico wrote: > There are blog posts out there about how large proportions of > applicants can't even write simple code on command... and I've taken > the questions and shown them to my siblings (who protest that they're > definitely not programmers), proving that a basic smattering of > mathematical nous puts you above people who are trying to earn money > from coding. > > It's like a carpenter, looking for a skilled assistant, and getting > people who don't know which end of a saw to hold. http://blog.codinghorror.com/why-cant-programmers-program/ Not everyone agrees that this is a thing: http://www.skorks.com/2010/10/99-out-of-100-programmers-cant-program-i-call-bullshit/ I'm inclined to accept that maybe 99 out of 100 *applications* for programming jobs are from people who can't program, but I don't think that 99 out of 100 *programmers* can't program. It's probably more like 65, maybe 70 out of 100, tops. Ha ha only serious. More here: http://www.protocolostomy.com/2010/03/15/programmers-that-cant-program/ -- Steven -- https://mail.python.org/mailman/listinfo/python-list
Re: netaddr value back to IP
Noah wrote:
> I am trying to get a value back to IP using the netaddr python module.
> How do I get the value 'ip' back to IP format? how is it done?
>
> snip
>
> print IPNetwork(v4_peer_ip).value
> ip = IPNetwork(v4_peer_ip).value + 1
> print ip
>
> --- snip ---
>>> ip=netaddr.IPAddress('192.168.71.20')
>>> ip+=1
>>> str(ip)
'192.168.71.21'
Ciao, Michael.
--
https://mail.python.org/mailman/listinfo/python-list
Re: A Freudian slip of *EPIC PROPORTIONS*!
On 2014-11-13, Rick Johnson wrote: > On the other hand, if the author is not GvR, then he is most > likely someone of great importance within the community. As much as I love Python, I hate the amount of appeal to authority that is present in the Python community. Ok, GvR created Python, great. He is extremely smart and knowledgable, no doubt. But that doesn't make him right on everything. That doesn't mean his opinion on something makes it True or False. Gooosh. -- ko -- https://mail.python.org/mailman/listinfo/python-list
Re: Bad file descriptor
On 13Nov2014 15:40, satishmlm...@gmail.com wrote: import os os.write(1, b'Hello descriptor world\n') OSError: Bad file descriptor How to give a file descriptor number to this function? How to get a file descriptor number? Wow, this must be at least the 4th post of the same question. It now occurs to me that a newer Python won't help you. Are you running this at a command prompt? Or are you running this in some IDE? The reason I ask this question is that at a command prompt, the above would probably work. In short, please provide more context. What OS? What version of Python? What environment (command prompt, IDE (which one?), a standalone script, etc)? CHeers, Cameron Simpson Louis Pasteur's theory of germs is ridiculous fiction. --Pierre Pachet, Professor of Physiology at Toulouse, 1872 -- https://mail.python.org/mailman/listinfo/python-list
