Re: Why tuples use parentheses ()'s instead of something else like 's?
Roy Smith wrote: In article [EMAIL PROTECTED], Reinhold Birkenfeld [EMAIL PROTECTED] wrote: + being an operator Looks more like a smiley for guy wearing a bowtie :)), I had a nice laugh with this one. -- http://mail.python.org/mailman/listinfo/python-list
Re: Complementary language?
On Sat, 25 Dec 2004 18:40:31 -0500, HackingYodel [EMAIL PROTECTED] wrote: Hello all! I'm learning to program at home. I can't imagine a better language than Python for this. The ideal situation, for me, would be to study two languages at the same time. Probably sounds crazy, but it works out better for me. Me too, thats why my web tutorial features Python, VBSCript and Javascript. (The previous version had BASIC and Tcl with Python) fascinating. C, D, Objective-C, Ocaml, C++, Lisp, how is a non-tech to choose? Does any single language do a better job in Python's weaker areas? C is better at low level stuff, Prolog is better at declaratie programming and Haskell is better at functional programming. Lisp/Scheme are good for giving a good theoretical understanding (try the SICP and HTDP web sites). And Tcl has a really different approach which is plain fun to grapple with :-) I chose VBScript and JavaScript because they have similar structure to Python (traditional imperative programming with OOP) but very different syntax. Plus they were free and easily available (albeit with VBScript limited to Windows users, who are 80+% of my visitors). Javascript is especially useful since its an easy lead in to learning C/C++, Java, even Perl to some extent and a lot of sample code sites use those languages. Alan G. Author of the Learn to Program website http://www.freenetpages.co.uk/hp/alan.gauld -- http://mail.python.org/mailman/listinfo/python-list
Re: OT: spacing of code in Google Groups
JanC [EMAIL PROTECTED] wrote in message news:[EMAIL PROTECTED] I don't know if gmane keeps formating of messages intact when posting? That could be an alternative too... Reading posts via gmane with Outlook Express preserves leading spaces just fine. However, OE deletes tabs regardless of what newsgroup does. The funny thing is that typing a tab gets converted to 4 spaces. Terry J. Reedy -- http://mail.python.org/mailman/listinfo/python-list
Re: exposing C array to python namespace: NumPy and array module.
On Sat, 2005-01-01 at 08:18, Bo Peng wrote:
Python's array module is built-in, easy to use, but *without* a
FromLenAndData function! Even the buffer interface provides only 'get
buffer' but no 'set buffer' functions. Could anyone tell me how I can
create an array object from existing data?
Python has no array objects in the core language, only lists. The
distinction is important when discussing numarray etc, because Python
lists and NumPy etc arrays are very different.
While you can build a Python list from a subsection of your C array,
changes made in Python won't be pushed back to the C array it was
created from. If this is OK, you can probably build the list using just
a for loop - I'm not sure if there are any more efficient methods for
variable length lists.
If the Python user needs to be able to change the underlying array, I'd
probably drop the use of the built-in list class entirely and write my
own class that looks like a list (and smells like a list, and tastes
like a list - lucky we didn't step in it!). It can be pretty simple,
providing as few of the list protocol methods as:
__getitem__ (a PyList_GetItem equivalent)
__setitem__ (a PyList_SetItem equivalent)
and preferably:
__len__
__iter__
or as much of the list protocol as documented on the Python/C API page
as you need.
I'd probably implement the class in Python, and have my extension module
provide a couple of simple functions to the underlying C array. These
could be considered private to your list class. That'd make writing
things like the __iter__ method much nicer, while still letting you
implement __len__, __getitem__, __setitem__, etc in C. For example, I
might write:
class CArray(object):
def __init__(self, ...):
...
def __getitem__(self, index):
_carray_getitem(self, index)
def __len__(self):
_carray_len(self, index)
def __iter__(self):
# build and return an interator using Python
...
If you want to write part of your extension module in Python and part in
C, there are two main ways to do it. The usual way is to write a
'wrapper' in Python that imports the C parts, wraps them where necessary
or just pushes them into its own namespace, etc.
The less common way is to import __builtins__ and __main__ into your C
extension module's namespace then PyRun_String() python code in it to
set things up. I find this approach MUCH more useful when embedding
Python in an app and I only want to write small bits of my module in
Python.
The other alternative is to code your class entirely in C, implementing
all the __methods__ as C functions. Unattractive as far as I'm
concerned, but then I find constructing classes using Python's C API
irritating and less clear than it could be.
Here's the code -- hideously reformatted to avoid wrapping in the mail -
in my initmodule() function that I use to set up the module so that
Python code can execute in its namespace. You can ignore the
const_cast stuff, chances are your compiler will ignore the const
problems.
// 'd' is the dictionary of the extension module, as obtained
// with PyModule_GetDict(module)
PyObject* builtinModule = PyImport_ImportModuleEx(
const_castchar*(__builtin__),
d, d, Py_BuildValue(const_castchar*([]))
);
if (builtinModule == NULL)
{
// Error handling will not be shown; it'll depend on your module anyway.
}
PyDict_SetItemString(d, const_castchar*(__builtin__),
builtinModule);
PyObject* exceptionsModule = PyImport_ImportModuleEx(
const_castchar*(exceptions), d, d,
Py_BuildValue(const_castchar*([]))
);
if (exceptionsModule == NULL) {}
PyDict_SetItemString(d, const_castchar*(exceptions),
exceptionsModule);
// We can now run Python code in the module's namespace. For
// example (untested), as my real examples wouldn't do you any
// good, they're too bound to the internal API of my module:
QString python_code = ;
python_code += def sample_function():\n;
python_code += print \See, it worked\\n;
// My app sets sysdefaultencoding to utf-8, hence:
char* python_code_cstring = python_code.utf8();
// Note that we pass our module dictionary as both
// locals and globals. This makes the code effectively
// run in the extension module, as if it was being
// run during loading of a Python module after an
// 'import' statement.
PyObject* result = PyRun_String(python_code_cstring,
Py_file_input,
d,d);
if (result == NULL)
{
qDebug(Python code to declare sample_function failed!);
PyErr_Print(); // also clears the exception
}
// Because 'result' may be NULL, not a PyObject*, we must call PyXDECREF
not Py_DECREF
Py_XDECREF(result);
--
Ugh - I'd forgotten how ugly C code limited to 80 cols and without
syntax highlighting really was. Especially when the reformatting is done
as badly as I've done it. I hope you can make some sense out of that,
anyway. Note that once
Re: Complementary language?
On Sat, 1 Jan 2005 09:35:32 + (UTC), Alan Gauld [EMAIL PROTECTED] wrote: On Sat, 25 Dec 2004 18:40:31 -0500, HackingYodel [EMAIL PROTECTED] wrote: Hello all! I'm learning to program at home. I can't imagine a better language than Python for this. The ideal situation, for me, would be to study two languages at the same time. Probably sounds crazy, but it works out better for me. Yes, the best way to learn a new language is probably to compare it with some other language (of the same paradigm) that you are already familiar with. The best part about Python is that there really isn't much learning involved. Python comes closest to what you'd call pseudocode. If you know your English, you probably know Python. :D Me too, thats why my web tutorial features Python, VBSCript and Javascript. (The previous version had BASIC and Tcl with Python) fascinating. C, D, Objective-C, Ocaml, C++, Lisp, how is a non-tech to choose? Does any single language do a better job in Python's weaker areas? C is better at low level stuff, Prolog is better at declaratie programming and Haskell is better at functional programming. Lisp/Scheme are good for giving a good theoretical understanding (try the SICP and HTDP web sites). And Tcl has a really different approach which is plain fun to grapple with :-) I chose VBScript and JavaScript because they have similar structure to Python (traditional imperative programming with OOP) but very different syntax. Plus they were free and easily available (albeit with VBScript limited to Windows users, who are 80+% of my visitors). Javascript is especially useful since its an easy lead in to learning C/C++, Java, even Perl to some extent and a lot of sample code sites use those languages. Alan G. Author of the Learn to Program website http://www.freenetpages.co.uk/hp/alan.gauld -- http://mail.python.org/mailman/listinfo/python-list -- Premshree Pillai http://www.livejournal.com/~premshree -- http://mail.python.org/mailman/listinfo/python-list
Re: The Industry choice
In article [EMAIL PROTECTED], Hans Nowak [EMAIL PROTECTED] wrote: Paul Rubin wrote: You should write unit tests either way, but in Python you're relying on the tests to find stuff that the compiler finds for you with Java. As I wrote on my weblog a while ago, I suspect that this effect is largely psychological. You jump through hoops, declaring types all over the place, checking exceptions, working around the language's limitations, etc. So when your code compiles, it *feels* safer. Like you're at least part of the way towards ensuring correctness. All that work must be good for *something*, right? Never mind that when writing unit tests for a dynamic language, you don't check for these things at all. How often do you explicitly check types in Python unit tests? IMHO, when using a dynamic language, you don't need most of the checks that Java, C# and their ilk force upon you. . . . Me, too. That is, while I have a LOT of respect for Paul's programming and judgment, and question myself when I'm on the side opposite him, I ultimately value type declarations in languages such as Java as more cost than benefit. It's a funny position to hold, because I simultaneously recognize that type theory is one of computing's strongest theoretical achievements, AND I am a strong advocate of static syntax checkers such as PyChecker. Still, I see TDD as the right place to start. -- http://mail.python.org/mailman/listinfo/python-list
Which blog tool
I currently use python to automatically summarise a certain newsgroup daily, and post the findings that it makes. Someone has suggested that they would like a to see a blog of the posts. I wondered if there was a python tool/library that could automate the blog postings. Any ideas? Some details: * the summaries are basically just text files * I already have a blog at www.blogger.com (http://markcarterturriff.blogspot.com/), so I would like to use that if possible; although any alternative free one that I can use to achieve my objective would be OK, too. * I do have my own hosted website, which can use perl but not python; but I'd rather use a freebie blog site * the whole thing must be scriptable, because it will run daily. A GUI would therefore likely get in the way. * generating an RSS feed would be nice -- http://mail.python.org/mailman/listinfo/python-list
Re: Speed ain't bad
Bulba! [EMAIL PROTECTED] wrote:
One of the posters inspired me to do profiling on my newbie script
(pasted below). After measurements I have found that the speed
of Python, at least in the area where my script works, is surprisingly
high.
Pretty good code for someone who calls himself a newbie.
One line that puzzles me:
sfile=open(sfpath,'rb')
You never use sfile again.
In any case, you should explicitly close all files that you open. Even
if there's an exception:
sfile = open(sfpath, 'rb')
try:
stuff to do with the file open
finally:
sfile.close()
The only thing I'm missing in this picture is knowledge if my script
could be further optimised (not that I actually need better
performance, I'm just curious what possible solutions could be).
Any takers among the experienced guys?
Basically the way to optimise these things is to cut down on anything
that does I/O: Use as few calls to os.path.is{dir,file}, os.stat, open
and such that you can get away with.
One way to do that is caching; e.g. storing names of known directories
in a set (sets.Set()) and checking that set before calling
os.path.isdir. I haven't spotted any obvious opportunities for that
in your script, though.
Another way is the strategy of it's easier to ask forgiveness than to
ask permission.
If you replace:
if(not os.path.isdir(zfdir)):
os.makedirs(zfdir)
with:
try:
os.makedirs(zfdir)
except EnvironmentError:
pass
then not only will your script become a micron more robust, but
assuming zfdir typically does not exist, you will have saved the call
to os.path.isdir.
- Anders
--
http://mail.python.org/mailman/listinfo/python-list
Re: Which blog tool
On Sat, 01 Jan 2005 13:14:23 +, Mark Carter [EMAIL PROTECTED] wrote: I currently use python to automatically summarise a certain newsgroup daily, and post the findings that it makes. Someone has suggested that they would like a to see a blog of the posts. I wondered if there was a python tool/library that could automate the blog postings. Any ideas? Some details: * the summaries are basically just text files * I already have a blog at www.blogger.com (http://markcarterturriff.blogspot.com/), so I would like to use that if possible; although any alternative free one that I can use to achieve my objective would be OK, too. You can use the Blogger API to post to your Blogger account. There's a Python interface to the API -- PyBlogger -- available here: http://beetle.cbtlsl.com/archives/category/pyblogger You could also use a free service like LiveJournal (http://www.livejournal.com/). There are several clients available to post to LJ. I don't know if a Python wrapper to post is available or not. IAC, it'd be a few lines of code to make the XML-RPC calls. The protocol docs are available here: http://www.livejournal.com/doc/server/ljp.csp.protocol.html HTH * I do have my own hosted website, which can use perl but not python; but I'd rather use a freebie blog site * the whole thing must be scriptable, because it will run daily. A GUI would therefore likely get in the way. * generating an RSS feed would be nice -- http://mail.python.org/mailman/listinfo/python-list -- Premshree Pillai http://www.livejournal.com/~premshree -- http://mail.python.org/mailman/listinfo/python-list
HELP: Tkinter idiom needed
Hi there, after reading TkInter/thread -recipe: http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/82965 I wondered if it was possible to avoid using threads for the following problem: I have script started from W2K console that normally prints ascii messages to the screen. However, I have command line debug -flag that might cause printing of UTF-8 data to the screen. This fails occassionally due to Console encoding, of course. What I need is Tkinter window where some printouts are directed when script is run in Debug -mode (Redirection of stdout is out of question). While testing, I have got this far already: ---script starts from Tkinter import * from ScrolledText import ScrolledText import os, sys, tkFont, codecs class Pyg_message_box: def __init__(self, parent): self.myParent = parent self.myContainer1 = Frame(parent) self.myContainer1.option_add(*font,\ tkFont.Font(family=Arial Unicode MS, size=8)) self.myContainer1.pack() self.text = ScrolledText() self.text.pack() self.button1 = Button(self.myContainer1, text=Quit,\ command=self.button1Click) self.button1.pack(side=LEFT) self.button1.bind(Button-1, self.button1Click) def button1Click(self, event): self.myContainer1.quit() def write(self, s): self.text.insert(END, s) root = Tk() widget = Pyg_message_box(root) sys.stdout = widget a = codecs.open(d:\\test.txt, r, utf_16).readlines() for x in a: print x root.mainloop() ---script ends My questions are: - Can I open Tk -window without enclosing the whole script between root=Tk() and root.mainloop()? - What is the idiom of opening Tk -window only when Debug -flag is encountered (the script stops running until window is closed)? Something like: if not my_debug == ON: print message # prints to console else: # 1) open temporary ScrolledText() Tk -window # 2) Print stuff to window # 3) Ask user to close window I would no like to always open Tkwindows just in case user runs script with debug -flag on. -pekka- -- http://mail.python.org/mailman/listinfo/python-list
Re: what is lambda used for in real code?
In article [EMAIL PROTECTED], Adam DePrince [EMAIL PROTECTED] wrote: We can operate on every other class without having to involve the namespace, why should functions be any different? def is a weird beast. It does more than just bind a lambda to a name, it also alters the function so it knows its own name. For example, the following: -- def foo (): print I am foo bar = foo def foo (): print I am foo's evil twin foo() print foo bar() print bar baz = lambda : I am lambda print baz print baz() -- will print: I am foo's evil twin function foo at 0x363c70 I am foo function foo at 0x35ae70 function lambda at 0x363770 I am lambda -- http://mail.python.org/mailman/listinfo/python-list
Re: what is lambda used for in real code?
Why not improve your metaclass wrapping so it knows about properties and replaces them with properties containing wrapped functions? Erg - never thought of that, actually - it was so fast to introduce the lambda... But after some tinkering with metaclasses, I think it can be done - I have to create a mapping between the pure, unwrapped function and the wrapped one so that I can recreate all properties. Thanks for nudging me in that direction :) -- Regards, Diez B. Roggisch -- http://mail.python.org/mailman/listinfo/python-list
DB-API 2.0 in pysqlite and pgdb
Happy New Year to all Pythoneers!
I am playing with pysqlite and pgdb and their DB-API conformancy.
It was quite interesting to know:
- sqlite doesn't have mandatory helper-functions Date, Tim, etc.
(due to an error int it's __init__, but this is quite obvious to correct
or just to use mx.Date, mx.Time)
more serious mishaps with pgdb (postgresql-python):
it doesn't know how to quote date-time data for the objects
it has constructors itself.
import pgdb
c = pgdb.connect(database=template1)
cu = c.cursor()
o = pgdb.Time(10, 0, 0)
cu.execute(select %(o);, vars())
Traceback (most recent call last):
File stdin, line 1, in ?
File /usr/local/lib/python2.3/site-packages/pgdb.py, line 189, in execute
self.executemany(operation, (params,))
File /usr/local/lib/python2.3/site-packages/pgdb.py, line 201, in
executemany
sql = _quoteparams(operation, params)
File /usr/local/lib/python2.3/site-packages/pgdb.py, line 283, in
_quoteparams
x[k] = _quote(v)
File /usr/local/lib/python2.3/site-packages/pgdb.py, line 275, in _quote
raise InterfaceError, 'do not know how to handle type %s' % type(x)
pgdb.InterfaceError: do not know how to handle type type 'instance'
This doesn't happen for strings or numbers:
cu.execute(select %s;, ['s'])
cu.execute(select %s;, [1])
cu.execute(select %(k)s;, {'k': 123})
o
DateTimeDelta object for '10:00:00.00' at 401e8a48
Thus, pgdb doesn't know how to handle DateTimeDelta.
The same with
cu.execute(select %(o)s;, {'o': pgdb.Date(2005,1,1)})
. . .
line 201, in executemany
sql = _quoteparams(operation, params)
File /usr/local/lib/python2.3/site-packages/pgdb.py,
line 283, in _quoteparams
x[k] = _quote(v)
File /usr/local/lib/python2.3/site-packages/pgdb.py,
line 275, in _quote
raise InterfaceError, 'do not know how to handle type
%s' % type(x)
pgdb.InterfaceError: do not know how to handle type type
'DateTime'
(It was after I commented out exception catch:
# except:
# raise OperationalError, internal error in '%s' % sql
in pgdb.py to see where the error occurs)
Am I missing something obvious or is it really a bug/feature of pgdb?
python2.3
postgresql-7.2.1
almost fresh mx.DateTime
Thank you!
Sincerely yours, Roman Suzi
--
[EMAIL PROTECTED] =\= My AI powered by GNU/Linux RedHat 7.3
--
http://mail.python.org/mailman/listinfo/python-list
Re: Which blog tool
Premshree Pillai wrote: You can use the Blogger API to post to your Blogger account. There's a Python interface to the API -- PyBlogger -- available here: http://beetle.cbtlsl.com/archives/category/pyblogger Hey, it Just Works! I got the whole basic thing working in a few minutes. It was exactly what I was looking for. Thanks for the link. -- http://mail.python.org/mailman/listinfo/python-list
want some extra cash, try this
want some extra cash, try this THIS REALLY CAN MAKE YOU EASY MONEY!! A little while back, I was on my computer having a grand old time, just like you are now and came across an article similar to this that said you could make thousands dollars within weeks with only an initial investment of $6.00! So I thought, Yeah, right, this must be a scam, but like most of us, I was curious, so I kept reading. Anyway, it said that you send $1.00 to each of the 6 names and address stated in the article. You then place your own name and address in the bottom of the list at #6, and post the article in at least 200 newsgroups. No catch, that was it. So after thinking it over, and talking to few people first, I thought about trying it. I figured what have I got to lose except 6 stamps and $6.00, right? Like most of us I was a little skeptical and a little worried about the legal aspects of it all, So I checked it out with the U.S. Post Office (1-800-725-2161) and they confirmed that it is indeed legal! Then I invested the measly $6.00. Well GUESS WHAT!!?. Within 7 days, I started getting money in the mail! I was shocked! I figured it would end soon, but the money just kept coming in. In my first week, I made about $25.00. By the end second week I had made a total over $1,000.00! In the third week I had over $10,000.00 and it's still growing. Its Certainly worth $6.00, and 6 stamps, I have spent more than that on the lottery!! Let me tell you how this works and most importantly, why it works?.STEP 1: Get 6 separate pieces of paper and write the following on each piece of paper PLEASE PUT ME ON YOUR MAILING LIST. Now get 6 US $1.00 bills and place ONE inside EACH of the 6 pieces of paper so the bill will not be seen through the envelope to prevent thievery. Next, place one paper in each stating the above phrase, your name and address, and a $1.00 bill. What you are doing is creating a service by this. THIS IS ABSOLUTELY LEGAL! Mail the 6 envelopes to the following addresses: #1) Jason Barone P.O. Box 1015 Glen Burnie, MD 21060-1015 #2) Jonathon Markwood 3308 Birdsong Way Birmingham, AL 35242 #3) Eben Mcgee 1876 #C Locust, Las Cruces, NM 88001 #4) Ricky DeMaio 471 McCutcheon rd, Hudson WI 54016 #5) P. Ortner 29 Briarlee Dr. Tonawanda, NY 14150 #6) O. Humphrey 8452 E. Louise Dr, Tucson, AZ 85730 STEP 2: Now take the #1 name off the list that you see above, move the other names up and add YOUR Name as number 6 on the list. STEP 3: Change anything you need to, but try to keep this article as close to original as possible. Now, post your amended article to at least 200 newsgroups, message board. All you need is 200, but remember, the more you post, the more money you make! Just copy this message, paste it in Word or Notepad, find message boards like this and paste away. Congratulations? THAT'S IT! All you have to do is jump to different newsgroups and post away, after you get the hang of it, and it will take about 30 seconds for each newsgroup! * REMEMBER, THE MORE NEWSGROUPS OR MESSAGE BOARD YOU POST IN, THE MORE MONEY YOU EILL MAKE!! BUT YOU HAVE TO POST A MINIMUM OF 200* That's it! You will begin receiving money from around the world within days! -- http://mail.python.org/mailman/listinfo/python-list
Re: exposing C array to python namespace: NumPy and array module.
Craig Ringer wrote: On Sat, 2005-01-01 at 08:18, Bo Peng wrote: Python's array module is built-in, easy to use, but *without* a FromLenAndData function! Even the buffer interface provides only 'get buffer' but no 'set buffer' functions. Could anyone tell me how I can create an array object from existing data? Python has no array objects in the core language, only lists. The distinction is important when discussing numarray etc, because Python lists and NumPy etc arrays are very different. Thank you very much for the detailed reply! Sorry if I was not clear enough. I was talking about the differece between python array module (http://docs.python.org/lib/module-array.html, Modules/arraymodule.c in the source tree) and NumPy array. They both use C-style memory block arrangement for efficient memory access. While NumPy has both, the array module is designed to be used purely in Python so there is no header file and no function to build an array from a pointer. One of the methods you suggested (creating a new type) already implemented in arraymodule.c. I am not sure if it is appropriate to add the file into my project and add a 'CreateFromLenAndBuf' function. Bo -- http://mail.python.org/mailman/listinfo/python-list
Re: pickling a subclass of tuple
fedor [EMAIL PROTECTED] wrote:
Hi all, happy new year,
I was trying to pickle a instance of a subclass of a tuple when I ran
into a problem. Pickling doesn't work with HIGHEST_PROTOCOL. How should
I rewrite my class so I can pickle it?
You're falling afoul of an optimization in pickle's protocol 2, which is
documented in pickle.py as follows:
# A __reduce__ implementation can direct protocol 2 to
# use the more efficient NEWOBJ opcode, while still
# allowing protocol 0 and 1 to work normally. For this to
# work, the function returned by __reduce__ should be
# called __newobj__, and its first argument should be a
# new-style class. The implementation for __newobj__
# should be as follows, although pickle has no way to
# verify this:
#
# def __newobj__(cls, *args):
# return cls.__new__(cls, *args)
#
# Protocols 0 and 1 will pickle a reference to __newobj__,
# while protocol 2 (and above) will pickle a reference to
# cls, the remaining args tuple, and the NEWOBJ code,
# which calls cls.__new__(cls, *args) at unpickling time
# (see load_newobj below). If __reduce__ returns a
# three-tuple, the state from the third tuple item will be
# pickled regardless of the protocol, calling __setstate__
# at unpickling time (see load_build below).
Essentially, and simplifying just a little...: you're inheriting
__reduce_ex__ (because you're not overriding it), but you ARE overriding
__new__ *and changing its signature* -- so, the inherited __reduce__ex__
is used, and, with this protocol 2 optimization, it essentially assumes
that __new__ is similarly used -- or, at least, that a __new__ is used
which does not arbitrarily change the signature!
So, if you want to change __new__'s signature, and yet be picklable by
protocol 2, you have to override __reduce_ex__ to return the right
args... those your class's __new__ expects!
For example, you could consider something like...:
def __newobj__(cls, *args):
return cls.__new__(cls, *args)
class A(tuple):
def __new__(klass, arg1, arg2):
return super(A, klass).__new__(klass, (arg1, arg2))
def __reduce_ex__(self, proto=0):
if proto = 2:
return __newobj__, (A, self[0], self[1])
else:
return super(A, self).__reduce_ex__(proto)
Note the key difference in A's __reduce_ex__ (for proto=2) wrt tuple's
(which is the same as object's) -- that's after an import a where a.py
has this code as well as an 'a = A(1, 2)'...:
a.a.__reduce_ex__(2)
(function __newobj__ at 0x3827f0, (class 'a.A', 1, 2))
tuple.__reduce_ex__(a.a, 2)
(function __newobj__ at 0x376770, (class 'a.A', (1, 2)), {}, None,
None)
Apart from the additional tuple items (not relevant here), tuple's
reduce returns args as (class 'a.A', (1, 2)) -- two items: the class
and the tuplevalue; so with protocol 2 this ends up calling A.__new__(A,
(1,2))... BOOM, because, differently from tuple.__new__, YOUR override
doesn't accept this signature! So, I suggest tweaking A's reduce so it
returns args as (class 'a.A', 1, 2)... apparently the only signature
you're willing to accept in your A.__new__ method.
Of course, if A.__new__ can have some flexibility, you COULD have it
accept the same signature as tuple.__new__ and then you wouldn't have to
override __reduce_ex__. Or, you could override __reduce_ex__ in other
ways, say:
def __reduce_ex__(self, proto=0):
if proto = 2:
proto = 1
return super(A, self).__reduce_ex__(proto)
this would avoid the specific optimization that's tripping you up due to
your signature-change in __new__.
The best solution may be to forget __reduce_ex__ and take advantage of
the underdocumented special method __getnewargs__ ...:
class A(tuple):
def __new__(klass, arg1, arg2):
return super(A, klass).__new__(klass, (arg1, arg2))
def __getnewargs__(self):
return self[0], self[1]
This way, you're essentially choosing to explicitly tell the normal
__reduce_ex__ about the particular arguments you want to be used for the
__new__ call needed to reconstruct your object on unpickling! This
highlights even better the crucial difference, due strictly to the
change in __new__'s signature...:
a.a.__getnewargs__()
(1, 2)
tuple.__getnewargs__(a.a)
((1, 2),)
It IS, I guess, somewhat unfortunate that you have to understand
pickling in some depth to let you change __new__'s signature and yet
fully support pickling... on the other hand, when you're overriding
__new__ you ARE messing with some rather deep infrastructure,
particularly if you alter its signature so that it doesn't accept
normal calls any more, so it's not _absurd_ that compensatory depth of
understanding is required;-).
Alex
--
http://mail.python.org/mailman/listinfo/python-list
Re: lies about OOP
[EMAIL PROTECTED] wrote: A paper finding that OOP can lead to more buggy software is at http://www.leshatton.org/IEEE_Soft_98a.html Sure, OOP *can* lead to more buggy software, that doesn't mean it always does. Les Hatton Does OO sync with the way we think?, IEEE Software, 15(3), p.46-54 This paper argues from real data that OO based systems written in C++ appear to increase the cost of fixing defects significantly when compared with systems written in either C or Pascal. It goes on to suggest that at least some aspects of OO, for example inheritance, do not fit well with the way we make mistakes. So, he has data that shows that C++ *appears* to increase the cost of fixing defects, then *suggests* that its because C++ is an OO language? Sounds like he is ignoring his own data to me... Mr. Hatton suffers from the same problem that many OO critics suffer. He thinks that the language choice decides whether the program written is an OO program. I've seen plenty of very non-OO systems written in OO languages, I've seen expert OO systems written in non-OO languages. OOP isn't a language choice, it is a style of problem solving. I'm happy to accept that it could take longer to fix bugs in programs written in C++ when compared to either C or Pascal, the language itself is quite a bit more complicated than either of the latter. You know, it tends to take longer to repair a 2004 Mustang than it does a 1964 Mustang, does that mean the newer car is not as good? If OOP is so beneficial for large projects, why are the Linux kernel, the interpreters for Perl and Python, and most compilers I know written in C rather than C++? All three of the systems in question were begun before C++ was standardized. Python was also implemented in Java, does that mean OO other than C++ is good? Of course not, the fact that the three projects in question were implemented in C is not an indictment against OO in any way. -- http://mail.python.org/mailman/listinfo/python-list
Re: lies about OOP
H. S. Lahman [EMAIL PROTECTED] wrote: Les Hatton Does OO sync with the way we think?, IEEE Software, 15(3), p.46-54 This paper argues from real data that OO based systems written in C++ appear to increase the cost of fixing defects significantly when compared with systems written in either C or Pascal. It goes on to suggest that at least some aspects of OO, for example inheritance, do not fit well with the way we make mistakes. Try and find and experienced OO developer who would advocate that large, complex generalizations are a good practice. You can write lousy programs in any paradigm. The likelihood increases when you use the most technically deficient of all the OOPLs. (If those developers had used Smalltalk, I'll bet their defect rates would have been substantially lower even if they weren't very good OO developers.) Careful, the paper never claims that C++ produced more defects than C or Pascal. It only claims that the defects found in the C++ program were more costly to fix. That is a very big difference. However, I agree completely with the rest of your comments. -- http://mail.python.org/mailman/listinfo/python-list
Windows process priority setting question...
Is it possible to have an app re-set its own priority? I see that 2.4+ has the ability for sub-processes, but only on creation. Apparently win32process.SetPriorityClass(handle, dwPriorityClass) and PyCWinThread.SetThreadPriority(priority) allows one to change a sub while a the sub is running, but what about the current? Ray -- http://mail.python.org/mailman/listinfo/python-list
Re: PyQT installation
[EMAIL PROTECTED] (Alex Martelli) writes: [...] Basically: if you want it on Windows for free, forget Qt Correct. (I hear the cygwin people are trying to make a GPL Qt available for Win+cyg+XFree, but I suspect trolltech ain't happy about that -- anyway, I don't think it would be native, X11 being still required). [...] Not correct. It's driven by KDE, and it's more ambitious than that: http://kde-cygwin.sourceforge.net/qt3-win32/roadmap.php IIRC, people have already run some KDE apps under Windows (though still needing X, so far). I wonder how TrollTech will react as (and if) it progresses. John -- http://mail.python.org/mailman/listinfo/python-list
Re: The Industry choice
Cameron Laird wrote: In article [EMAIL PROTECTED], [EMAIL PROTECTED] wrote: Bulba wrote: OK, so what projects and why would you consider Python: 1. clearly unsuitable Large-scale scientific computing projects, such as numerical weather prediction, where performance is critical. Python could be used as the glue but not the guts, where Fortran 95 and C++ are more appropriate. In my tests, some posted here, there has been a . . . I feel like growling that it's clearly a mistake for large-scale scientific computing projects not to leverage dynamic languages, at least in part. Yes, I've seen projects that would have been disasters if done entirely in Python. I've also seen many, many large-scale scientific projects that soaked up far more resources than they should have because they limited themselves to C++ or Fortran. I argue that it's a false opposition to categorize projects in terms of use of single languages. Many projects are MUCH better off with a mix of Python and Fortran, say (and probably SQL and JavaScript and ...), and it's pernicious to accomodate the managerial conceit that One Language will suffice. Indeed it's sensible to choose language based on the nature of the task to be performed, to avoid language-blindness and to build systems in mixed languages. Unfortunately the hierarchy of power in most modern commercial and academic organizations is such that large-scale efforts will be nominally run by single individuals, and since those individuals typically can dispense favors and determine who advances within the organization it's often unwise *not* to accommodate the managerial conceit it career advancement is one's primary goal. which-is-why-i-run-my-own-business-ly y'rs - steve -- Steve Holden http://www.holdenweb.com/ Python Web Programming http://pydish.holdenweb.com/ Holden Web LLC +1 703 861 4237 +1 800 494 3119 -- http://mail.python.org/mailman/listinfo/python-list
Re: PyQT installation
John J. Lee wrote: [EMAIL PROTECTED] (Alex Martelli) writes: [...] Basically: if you want it on Windows for free, forget Qt Correct. I believe the book C++ GUI programming Qt3 comes with a windows Qt gpl 3.x version. Just have to buy the book. No PyQt version to match thou. Blackadder from the Kompany, while not free, is still a pretty good deal. Like $100 for personal and around $350 for commercial version. Include current windows/linux versions of (Qt)PyQt along with converted Qt C++ to PyQt docs. Not correct. It's driven by KDE, and it's more ambitious than that: http://kde-cygwin.sourceforge.net/qt3-win32/roadmap.php IIRC, people have already run some KDE apps under Windows (though still needing X, so far). I wonder how TrollTech will react as (and if) it progresses. I don't think your giving TrollTech any credit here, yes they have a business model and need to make money, but not everybody is Microsoft. They are fully aware and supportive of the project and I remember reading not to long ago they struck an aggrement with the project that if anything ever happened to TrollTech they would release Qt to project under gpl, or something like that. -- http://mail.python.org/mailman/listinfo/python-list
Re: what is lambda used for in real code?
Steve Holden [EMAIL PROTECTED] wrote:
Adam DePrince wrote:
[...]
In sort, we must preserve the ability to create an anonymous function
simply because we can do so for every other object type, and functions
are not special enough to permit this special case.
And you'd create an anonymous type how, exactly?
type('',(),{})
class '__main__.'
maybe...?
Alex
--
http://mail.python.org/mailman/listinfo/python-list
Re: exposing C array to python namespace: NumPy and array module.
On Sat, 2005-01-01 at 10:27 -0600, Bo Peng wrote: Sorry if I was not clear enough. I was talking about the differece between python array module (http://docs.python.org/lib/module-array.html, Modules/arraymodule.c in the source tree) and NumPy array. They both use C-style memory block arrangement for efficient memory access. While NumPy has both, the array module is designed to be used purely in Python so there is no header file and no function to build an array from a pointer. Thanks for clarifying that - I had misunderstood your reference to arraymodule.c . I guess the core language doesn't have an array type, but as there's a standard lib module that does (I'd forgotten it was there), it hardly matters. It would seem sensible to extend that module with a C API for mapping an existing array. That would be a rather handy thing to have in the standard library. One of the methods you suggested (creating a new type) already implemented in arraymodule.c. I am not sure if it is appropriate to add the file into my project and add a 'CreateFromLenAndBuf' function. That sounds like a reasonable approach to me, but I'm hardly an expert. The code's license permits you to do so, and it's hardly worth repeating the work if you don't have to. -- Craig Ringer -- http://mail.python.org/mailman/listinfo/python-list
Re: exposing C array to python namespace: NumPy and array module.
Bo Peng wrote: Dear list, I am writing a Python extension module that needs a way to expose pieces of a big C array to python. Currently, I am using NumPy like the following: PyObject* res = PyArray_FromDimsAndData(1, int*dim, PyArray_DOUBLE, char*buf); Users will get a Numeric Array object and can change its values (and actually change the underlying C array). This works fine. However, when I deliver my module, I find NumPy is unnecessarily large for this simple task. As a matter of fact, I had to build from source NumPy, ATLAS etc on Solaris, Linux, Mac and if a user would like to use my module, he has to do the same thing! Python's array module is built-in, easy to use, but *without* a FromLenAndData function! Even the buffer interface provides only 'get buffer' but no 'set buffer' functions. Could anyone tell me how I can create an array object from existing data? Some vague ideas might be used: 1. PyCObject (I do not really understand the manual), 2. copy and modify arraymodule.c to my project (doable at all? License issue?) 3. Create an array object and hack it. (no api to do this.) I would strongly suggest an arraymodule.h with Array_FromLenAndData. Many thanks in advance. Bo I don't know how much this will help but when I am faced with a problem like this, I use Pyrex and look at the generated code. All you need to do in Pyrex is import the array module and create your array like you would in Python. To get the data into the array you will need to use the buffer interface and fill it in from your C code. -- http://mail.python.org/mailman/listinfo/python-list
Re: PyQT installation
On Sat, 1 Jan 2005, Ken Godee wrote: [...] I believe the book C++ GUI programming Qt3 comes with a windows Qt gpl 3.x version. Just have to buy the book. No PyQt version to match thou. GPL only if you buy the book makes no sense. Either it's GPL or it isn't. (It isn't, in fact.) [...] IIRC, people have already run some KDE apps under Windows (though still needing X, so far). I wonder how TrollTech will react as (and if) it progresses. I don't think your giving TrollTech any credit here, yes they have a business model and need to make money, but not everybody is Microsoft. They are fully aware and supportive of the project and I remember reading not to long ago they struck an aggrement with the project that if anything ever happened to TrollTech they would release Qt to project under gpl, or something like that. I'd forgotten about that agreement (again, driven by KDE). Reassuring, assuming the legalese corresponds to what one assumes is the spirit of it, and that it will hold water if/when tested in the courts. I am surprised if they support the effort to make a GPL native MS Windows version of Qt. They wouldn't have to be evil monopolists to be concerned about this development, IMHO. John -- http://mail.python.org/mailman/listinfo/python-list
Re: The Industry choice
Donn Cave wrote: Quoth Hans Nowak [EMAIL PROTECTED]: | Paul Rubin wrote: | | You should write unit tests either way, but in Python you're relying | on the tests to find stuff that the compiler finds for you with Java. | | As I wrote on my weblog a while ago, I suspect that this effect is | largely psychological. You jump through hoops, declaring types all over | the place, checking exceptions, working around the language's | limitations, etc. So when your code compiles, it *feels* safer. Like | you're at least part of the way towards ensuring correctness. All that | work must be good for *something*, right? Never mind that when writing | unit tests for a dynamic language, you don't check for these things at | all. How often do you explicitly check types in Python unit tests? | IMHO, when using a dynamic language, you don't need most of the checks | that Java, C# and their ilk force upon you. I have been fooling around with strongly, statically typed languages for a couple of years, in my spare time - Objective CAML, Haskell, O'Haskell. This is a little different experience than what you two are talking about - I don't think Java, C# and their ilk are quite as rigorous, nor do they use type inference - but as much as it would probably gag an FP enthusiast to say this, the basic idea is the same. I can only believe that if you think the benefit of static typing is psychological, either something is very different between the way you and I write programs, or you're not doing it right. I do think it makes more sense in functional languages like the ones you mention... that's one of the reasons I am trying to learn OCaml. I don't think the type systems in OCaml, Haskell etc can quite be compared to what's used in Java, C#, C++ or Delphi. So far, I am getting the impression that the type system in OCaml is actually there to help you, rather than something that gets in your way. I concur that in my OCaml experiments so far, errors pointed out by the compiler made a lot more sense, because they pointed to actual problems, rather than being a case of you didn't declare this method as public static final. Of course, it helps that, like Python, said languages (OCaml, Haskell) are higher-level than Java/C#/etc, so you can express things concisely and clearly. That might be one of the reasons why static, strong typing in VHLLs has a much higher return on investment than it has in lower-level languages, where you have to write acres of code just to get something done (availability of libraries notwithstanding). -- Hans Nowak http://zephyrfalcon.org/ -- http://mail.python.org/mailman/listinfo/python-list
Re: The Industry choice
For managers of companies it's worse: the company makes VERY substantial investments into any technology it marries, and that means big losses if it goes. Long-term stability of this technology in terms of we're not going to be left out in cold alone with this technology to feed it means a lot to them. Even a poor technology with external backing of big, stable vendor is better than the excellent technology without .. There is the stability issue you mention... but also probably the fear issue. If you choose a solution from a major company -- then it fails for some reason or they drop the product -- it's their fault -- you've got an automatic fall guy. On the other hand, an open source solution or otherwise less accepted solution ... it will probably be consider your fault by the organization. It's a rational decision to avoid personal risk when you don't get much reward for choosing something different. Rob -- http://mail.python.org/mailman/listinfo/python-list
Python equivalent of script(1)
Is there anything like script(1) for python interactive sessions. From script(1) manpage: Script makes a typescript of everything printed on your terminal. It is useful for students who need a hardcopy record of an interactive session as proof of an assignment, as the typescript file can be printed out later with lpr(1). If the argument file is given, script saves all dialogue in file. If no file name is given, the typescript is saved in the file typescript. In my case I wouldn't like to use it as a proof of anything, but I want to get a script accessing a library system in my school -- it means many attempts to play with urllib. I would prefer to do it in an interactive session, but then I would love to have a record of all what I've done, so I can edit this record into final script. Thanks for any hint, Matej Cepl -- http://mail.python.org/mailman/listinfo/python-list
Re: Python equivalent of script(1)
[EMAIL PROTECTED] writes: I would love to have a record of all what I've done, so I can edit this record into final script. You can save the current input history with import readline readline.write_history_file(python.log) If you want to log your whole session, including output, try using the 'screen' utility. HTH - Thomas -- If you want to reply by mail, substitute my first and last name for 'foo' and 'bar', respectively, and remove '.invalid'. -- http://mail.python.org/mailman/listinfo/python-list
Re: Python equivalent of script(1)
Thanks a lot. -- http://mail.python.org/mailman/listinfo/python-list
Re: what is lambda used for in real code?
Alex Martelli wrote:
Steve Holden [EMAIL PROTECTED] wrote:
Adam DePrince wrote:
[...]
In sort, we must preserve the ability to create an anonymous function
simply because we can do so for every other object type, and functions
are not special enough to permit this special case.
And you'd create an anonymous type how, exactly?
type('',(),{})
class '__main__.'
maybe...?
Indeed. And then you'd insert all the methods as lambdas by
We both know that the Python language framework has enough introspection
capabilities to do this, but I'm pretty sure you wouldn't try to pretend
that this would represent a realistic programming style. Or am I wrong?
regards
Steve
--
Steve Holden http://www.holdenweb.com/
Python Web Programming http://pydish.holdenweb.com/
Holden Web LLC +1 703 861 4237 +1 800 494 3119
--
http://mail.python.org/mailman/listinfo/python-list
Looping using iterators with fractional values
Hello,
Making the transition from Perl to Python, and have a
question about constructing a loop that uses an iterator
of type float. How does one do this in Python?
In Perl this construct quite easy:
for (my $i=0.25; $i=2.25; $i+=0.25) {
printf %9.2f\n, $i;
}
Thanks in advance for your help.
Daran Rife
[EMAIL PROTECTED]
--
http://mail.python.org/mailman/listinfo/python-list
Re: The Industry choice
Rob Emmons wrote: For managers of companies it's worse: the company makes VERY substantial investments into any technology it marries, and that means big losses if it goes. Long-term stability of this technology in terms of we're not going to be left out in cold alone with this technology to feed it means a lot to them. Even a poor technology with external backing of big, stable vendor is better than the excellent technology without .. There is the stability issue you mention... but also probably the fear issue. If you choose a solution from a major company -- then it fails for some reason or they drop the product -- it's their fault -- you've got an automatic fall guy. On the other hand, an open source solution or otherwise less accepted solution ... it will probably be consider your fault by the organization. It's a rational decision to avoid personal risk when you don't get much reward for choosing something different. You are ignoring the fact that with the open source solution you do at least have the option of hiring bright programmers to support the framework which has now become moribund, whereas when a company goes bust there's no guarantee the software IP will ever be extricated from the resulting mess. So I'm not sure I'd agree with rational there, though comprehensible might be harder to argue with. Personally I'd feel in a better position standing before a Board of Directors and saying While it's true that our chosen software platform isn't being supported by the original team any more, we do have options to continue to move it forward, including forming a consortium with other users. Avoidance of blame is way too large a motivator in large organizations, and it leads to many forms of sub-optimal decision making. regards Steve -- Steve Holden http://www.holdenweb.com/ Python Web Programming http://pydish.holdenweb.com/ Holden Web LLC +1 703 861 4237 +1 800 494 3119 -- http://mail.python.org/mailman/listinfo/python-list
Re: Looping using iterators with fractional values
drife wrote: Hello, Making the transition from Perl to Python, and have a question about constructing a loop that uses an iterator of type float. How does one do this in Python? Use a generator: def iterfloat(start, stop, inc): ... f = start ... while f = stop: ... yield f ... f += inc ... for x in iterfloat(0.25, 2.25, 0.25): ... print '%9.2f' % x ... 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 -- http://mail.python.org/mailman/listinfo/python-list
I need some advice/help on running my scripts
For the last couple of months I have been reading and working throught the examples in Magnus Lie Hetland's Book Practical Python This for all practical purposes is the first computer programming language I have spent any time at learning, so much of what I have covered in the book was for the first time. My problem is that many of the example scripts are run on Linux machines and I am using Win XP Pro. Here is a specific example of what is confusing me. If I want to open a file from the dos prompt in some script do I just write the name of the file I want to open (assuming it is in the same directory) after the script name? such as c:\some_script.py some_text_file.txt Does piping work the same way in dos as it does on a linux machine? And last but not least, is there a way to do this all from IDLE? -- http://mail.python.org/mailman/listinfo/python-list
Re: Python equivalent of script(1)
On 2005-01-01, [EMAIL PROTECTED] [EMAIL PROTECTED] wrote: Is there anything like script(1) for python interactive sessions. $ script transcript.txt Script started, file is transcript.txt $ python ... Not sure if there's a way to shut off readline... -- Grant Edwards grante Yow! But was he mature at enough last night at the visi.comlesbian masquerade? -- http://mail.python.org/mailman/listinfo/python-list
Re: Looping using iterators with fractional values
drife wrote:
Hello,
Making the transition from Perl to Python, and have a
question about constructing a loop that uses an iterator
of type float. How does one do this in Python?
In Perl this construct quite easy:
for (my $i=0.25; $i=2.25; $i+=0.25) {
printf %9.2f\n, $i;
}
=Py2.3:
for i in [x/4.0 for x in xrange(1, 10)]:
print %9.2f % i
Py2.4:
for i in (x/4.0 for x in xrange(1, 20)):
print %9.2f % i
Reinhold
--
http://mail.python.org/mailman/listinfo/python-list
Re: Python equivalent of script(1)
[EMAIL PROTECTED] writes: In my case I wouldn't like to use it as a proof of anything, but I want to get a script accessing a library system in my school -- it means many attempts to play with urllib. I would prefer to do it in an interactive session, but then I would love to have a record of all what I've done, so I can edit this record into final script. Thanks for any hint, Emacs will do that for you, either in a shell (command shell) or in a Python shell. Edit a python file, and type C-C ! and it'll start an interactive python in a buffer that will save all the output. Of course, you can also run your python after running script. That will log everything from the python session in the script file. mike -- Mike Meyer [EMAIL PROTECTED] 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: Looping using iterators with fractional values
Mark McEahern wrote: drife wrote: Hello, Making the transition from Perl to Python, and have a question about constructing a loop that uses an iterator of type float. How does one do this in Python? Use a generator: def iterfloat(start, stop, inc): ... f = start ... while f = stop: ... yield f ... f += inc ... for x in iterfloat(0.25, 2.25, 0.25): ... print '%9.2f' % x ... 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 Or use the numarray module: py import numarray as na py for f in na.arange(0.25, 2.25, 0.25): ... print '%9.2f' % f ... 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 Steve -- http://mail.python.org/mailman/listinfo/python-list
Re: what is lambda used for in real code?
Steve Holden [EMAIL PROTECTED] wrote:
...
And you'd create an anonymous type how, exactly?
type('',(),{})
...
Indeed. And then you'd insert all the methods as lambdas by
We both know that the Python language framework has enough introspection
capabilities to do this, but I'm pretty sure you wouldn't try to pretend
that this would represent a realistic programming style. Or am I wrong?
Calling 'type' to make a new type on the fly is occasionally neat -- not
quite as often as (say) using 'lambda', maybe;-). Neither should be a
'programming _style_' as opposed to an occasional convenience -- of the
two, lambda has more sensible use cases, but is also more prone to
overuse in practice. Also, the ability to call 'type' to make a type
adds zero complexity or issues to the language: it's basically zero
cost, just like the ability to call 'int' to make an int, and so on.
This can't be said of lambda, alas: it has a non-zero cost in terms of
(slightly) 'fattening' the language.
Alex
--
http://mail.python.org/mailman/listinfo/python-list
Re: I need some advice/help on running my scripts
Sean wrote:
My problem is that many of the example scripts are run on Linux
machines and I am using Win XP Pro. Here is a specific example of what
is confusing me. If I want to open a file from the dos prompt in some
script do I just write the name of the file I want to open (assuming it
is in the same directory) after the script name?
such as
c:\some_script.py some_text_file.txt
It's unclear to me what you want to do here. If your some_script.py
looks like:
import sys
f = file(sys.argv[1])
then yes, you can call some_script.py as above, and the file will be
readable from the 'f' file object.
Does piping work the same way in dos as it does on a linux machine?
Mostly:
[D:\Steve]$ type test.py
import sys
for i, line in enumerate(sys.stdin):
sys.stdout.write(%i:%s % (i, line))
[D:\Steve]$ type input.txt
A
B
C
D
[D:\Steve]$ python test.py input.txt
0:A
1:B
2:C
3:D
[D:\Steve]$ python test.py output.txt
Z
Y
X
^Z
^Z
[D:\Steve]$ type output.txt
0:Z
1:Y
2:X
[D:\Steve]$ python test.py input.txt output.txt
[D:\Steve]$ type output.txt
0:A
1:B
2:C
3:D
[D:\Steve]$ type input.txt | python test.py
0:A
1:B
2:C
3:D
Note however, that you may run into problems if you don't explicitly
call python:
[D:\Steve]$ test.py input.txt
Traceback (most recent call last):
File D:\Steve\test.py, line 2, in ?
for i, line in enumerate(sys.stdin):
IOError: [Errno 9] Bad file descriptor
And last but not least, is there a way to do this all from IDLE?
What exactly do you want to do? You can certainly type something like:
f = file('input.txt')
in IDLE to get access to the 'input.txt' file...
Steve
--
http://mail.python.org/mailman/listinfo/python-list
What can I do with Python ??
Beginners question, but really what can you do with it ? How hard is Python to learn compared with other languages (let's say C#). Can you make fullscreen game with it (for example) ? I've looked at http://www.python.org but nothing concrete there -- http://mail.python.org/mailman/listinfo/python-list
Re: Clearing the screen
In the darkest hour on Sat, 25 Dec 2004 09:41:54 +1030, Ishwor [EMAIL PROTECTED] screamed: def cls(): for i in range(1,40): print ; Slightly ot, but perhaps this'll work for you: def cls(): print \033[2J -- [ Artur M. Piwko : Pipen : AMP29-RIPE : RLU:100918 : From == Trap! : SIG:217B ] [ 22:06:17 user up 10478 days, 10:01, 1 user, load average: 0.06, 0.06, 0.06 ] Even God cannot change the past. -- http://mail.python.org/mailman/listinfo/python-list
Re: exposing C array to python namespace: NumPy and array module.
Bo Peng wrote: Dear list, I am writing a Python extension module that needs a way to expose pieces of a big C array to python. Currently, I [use] NumPy Users ... actually change the underlying C array. Python's array module is built-in, easy to use, but *without* a FromLenAndData function! Python's array module is not built to do this well. It can re-size the array, delete elements inside the array, and other things that don't work very well with C-managed data. I wrote blocks and views to overcome this problem. A View of data can be pointed at data, and the view behaves much like a Python array (except that you cannot affect the array's size). You can even take slices of the view, which will produce a new view referring to the same base memory. There are two kinds of views available, read-only views and writable views. Have a look at: http://members.dsl-only.net/~daniels/Block.html to see if it addresses your problem. It is MIT-licensed (give credit, but feel free to use). Let me know if it works OK, could use a tweak, or is completely useless. I'll be more than happy to respond to questions. --Scott David Daniels [EMAIL PROTECTED] -- http://mail.python.org/mailman/listinfo/python-list
Re: Looping using iterators with fractional values
Mike Meyer wrote: Or - and much safer when dealing with floating point numbers - iterate over integers and generate your float values: for j in range(1, 9): i = j * .25 print %9.2f % i There's a glitch there, though - should be range(1, 10). Reinhold PS: I'm wondering whether my genexp approach or this one is preferable. Readability is equal, I would say, but how about speed? Brought up a few timeits: Python 2.3 -- for i in [x/4.0 for x in range(1, 10)]: 36,9 sec for j in range(1, 10): i = j * 0.25: 33,7 sec Python 2.4 -- for i in (x/4.0 for x in range(1, 10)): 32,5 sec for j in range(1, 10): i = j * 0.25: 28,4 sec So what does that tell us? (a) don't use genexps where there is a simpler approach (b) Py2.4 rocks! Reinhold -- http://mail.python.org/mailman/listinfo/python-list
Re: Securing a future for anonymous functions in Python
Doug Holton [EMAIL PROTECTED] writes:
Steven Bethard wrote:
Simo Melenius wrote:
map (def x:
Oops, I found a typo alreay. I meant to write def (x): -- no name
for anonymous functions but just the argument list, please :)
Right the comma plus other things make this difficult for a parser to
handle correctly. Other people have already come up with working
It is difficult since in Python we don't enjoy the ugly luxury of
stuffing statements inside {}s. But as Bengt pointed out, parentheses
don't actually look bad at all in this case.
Then the multi-line way. I had to add an overload of map to support
reversing the order of parameters (list first, then the closure):
newlist = map([1,2,3,4,5,6]) def (x as int):
return x*x*x
That doesn't seem to scale if you want to pass more than one anonymous
function arguments to the function or call an arbitrary function with
parameters in arbitrary order.
br,
S
--
http://mail.python.org/mailman/listinfo/python-list
Re: PyQT installation
Ken Godee wrote: I believe the book C++ GUI programming Qt3 comes with a windows Qt gpl 3.x version. Just have to buy the book. No PyQt version to match thou. No, Sir. It's a non-commercial edition. At the request from Trolltech, there's no PyQt-nc available for this version of Qt. Blackadder from the Kompany, while not free, is still a pretty good deal. Like $100 for personal and around $350 for commercial version. Include current windows/linux versions of (Qt)PyQt along with converted Qt C++ to PyQt docs. This is much better way to get PyQt for Windows! -- Jarek Zgoda http://jpa.berlios.de/ | http://www.zgodowie.org/ -- http://mail.python.org/mailman/listinfo/python-list
Re: UserDict deprecated
Uwe Mayer wrote: Why is the UserDict module is deprecated after Python 2.2. The application of it I have in mind is, i.e. multiple inheritance from file and dic - which is not possible. I am curious, what would you do with a class that derives from both file and dict? -- Hans Nowak http://zephyrfalcon.org/ -- http://mail.python.org/mailman/listinfo/python-list
Re: UserDict deprecated
Uwe Mayer wrote: Why is the UserDict module is deprecated after Python 2.2. The application of it I have in mind is, i.e. multiple inheritance from file and dic - which is not possible. [...] I was writing a class that read /writes some binary file format. I implemented the functions from the file interface such that they are refering to records. However, the file format has some header fields and I'd wanted to grant access to those via the dict-interface. Another example: working with PyQt I have an instance of a QListView and wanted to use the list-interface to get and set individual records. If it's just a matter of attribute access, implementing the relevant __getitem__ and __setitem__ methods will probably suffice. I don't think that deriving from dict or list will do you much good here... most of the methods will be irrelevant, or won't do what you want, so you have to override them anyway. -- Hans Nowak http://zephyrfalcon.org/ -- http://mail.python.org/mailman/listinfo/python-list
Approximating scattered data
I've been looking for some way to approximate scattered 3D data points in Python. The data doesn't seem to be amenable to fitting functions like polymials, so I may have to use something more like a spline surface. However, I can't find anything usable from Python, and my Fortram skills are pretty rusty. I tried SciPy, but it's spline fitting module doesn't work at all for my data. I've found mentions of a Python port NURBS toolbox, but all the links I can find are broken. I've also found references to Fortran programs from netlib/toms, but I was hoping there might be something that was already usable from Python. Can anybody point me toward a Python module for approximating scattered data using something like a Renka algorithm? -- Grant Edwards grante Yow! How do I get HOME? at visi.com -- http://mail.python.org/mailman/listinfo/python-list
Re: The Industry choice
Steve Holden [EMAIL PROTECTED] writes: It seems to me that IDLE and a lot of the rest of Python are examples of someone having a cool idea and writing a demo, then releasing it with a lot of missing components and rough edges, without realizing that it can't reasonably be called complete without a lot more work. ^Python^open source^ I wouldn't say so. I'd say the Linux kernel, GCC, Emacs, Apache, Mozilla, etc. are all developed with a much more serious attitude than Python is. Of course there are lots of other FOSS programs that someone wrote for their own use and released, that are less polished than Python, but that are also the subject of less advocacy than Python. -- http://mail.python.org/mailman/listinfo/python-list
Re: The Industry choice
[EMAIL PROTECTED] (Cameron Laird) writes: That is, while I have a LOT of respect for Paul's programming and judgment, and question myself when I'm on the side opposite him, I ultimately value type declarations in languages such as Java as more cost than benefit. I don't find static type declarations to have much cost. It's just a few more keystrokes. I'm open to persuasion about whether they have benefit. I do believe that it's a horrible deficiency in Python that it has no declarations at all, even optional ones, like perl -w or use strict. Python's scoping hacks that result from the lack of declarations just seem to me like pure insanity. I was pretty skeptical of Java's checked exceptions when I first used them but have been coming around about them. There's just been too many times when I wrote something in Python that crashed because some lower-level function raised an exception that the upper level hadn't been expecting, after the program had been in use for a while. I'd sure rather find out about that at compile time. -- http://mail.python.org/mailman/listinfo/python-list
Re: UserDict deprecated
Uwe Mayer wrote: Saturday 01 January 2005 22:48 pm Hans Nowak wrote: I am curious, what would you do with a class that derives from both file and dict? I was writing a class that read /writes some binary file format. I implemented the functions from the file interface such that they are refering to records. However, the file format has some header fields and I'd wanted to grant access to those via the dict-interface. If you implemented the file interface functions yourself, why do you want to inherit from file? Another example: working with PyQt I have an instance of a QListView and wanted to use the list-interface to get and set individual records. But just inheriting from list won't make this work, will it? Don't you want to do something like: class C(QListView): def __getitem__(self, i): return self.getIndividualRecord(i) # or whatever method gives # you the record Steve -- http://mail.python.org/mailman/listinfo/python-list
Re: UserDict deprecated
Uwe Mayer [EMAIL PROTECTED] wrote: ... If I used UserDict I would not need to specify all methods UserDict provides alreay, anyway. The DictMixin class from the UserDict module is *not* deprecated -- only the UserDict class from the same module. (If you found info saying otherwise pls provide a URL: the info is wrong and I'll try to get it fixed -- thanks!). DictMixin's purpose is exactly as you state: letting you make a complete mapping class out of one which only supplies the very basics, by mix-in inheritance. Alex -- http://mail.python.org/mailman/listinfo/python-list
Re: Looping using iterators with fractional values
Mike Meyer wrote: Or - and much safer when dealing with floating point numbers - iterate over integers and generate your float values: for j in range(1, 9): i = j * .25 print %9.2f % i I agree with this suggestion. As an historical aside, Fortran had loops with floating point variables for decades, but in 1995, the first standard in a while to REMOVE features, this was one of the few things deleted. The Fortran standards committee is very conservative about creating backwards incompatibilities, but they must have thought loops with floating point variables are so error-prone -- and alternatives with integer counters are so easy to write -- that they put their foot down. I know the OP is asking about Python, but the principle is the same. -- http://mail.python.org/mailman/listinfo/python-list
Re: What can I do with Python ??
BOOGIEMAN [EMAIL PROTECTED] wrote: Beginners question, but really what can you do with it ? You can write application programs, big or small, of just about any kind you may imagine, on just about any platform you may imagine (from mainframes and supercomputers down to powerful cellphones such as Nokia's S-60 series). How hard is Python to learn compared with other languages (let's say C#). Python is among the simplest languages to learn. Can you make fullscreen game with it (for example) ? Sure! Have you thought of using google? The first 2 hits for python games are on www.pygame.org, This allows you to create fully featured games and multimedia programs in the python language, as the google snippet says. The third hit is for the book Game Programming With Python on the amazon site. The 4th one is about Month Python, but the fifth is back to our subject -- a Python Game Programming page full of useful links. Then you get another link to the same book, a link to a different book, c. I've looked at http://www.python.org but nothing concrete there You _gotta_ be kidding, right...? The Beginner's Guide link takes you right to the BeginnersGuide page which starts with the reassurance that Python is easy to learn even if you're new to programming and continues with a zillion useful links. The Python Books link takes you to a huge list of books, and the FIRST subheading under specific applications is for game programming, leading you to the two books I already mentioned. There's a Search bar, enter Game there, and the FIRST hit is http://www.python.org/moin/GameProgramming which STARTS with the reassurance that, yes, you CAN write whole games in Python, and besides PyGame also points you to PyKira, a fast game development framework for Python (which) also supports MPEG video, sound (MP3, Ogg Vorbis, Wav and Multichannel module files), direct images reading and much more. Etc, etc, ...!!! How much more concrete could you expect *ANY* blessed website to BE, for Pete's sake?!??! Alex -- http://mail.python.org/mailman/listinfo/python-list
Re: exposing C array to python namespace: NumPy and array module.
Bo Peng wrote: Scott David Daniels wrote: I wrote blocks and views to overcome this problem. I was too impatient to wait for your reply. :-) I call 21-hour turnaround over New Year's Eve pretty good. Clearly I will never be quick enough for you ;-). Since I presented this at the Vancouver Python Workshop last August, I'll claim a negative five months response time (possibly a personal best). --Scott David Daniels [EMAIL PROTECTED] -- http://mail.python.org/mailman/listinfo/python-list
Re: What can I do with Python ??
On Sat, 1 Jan 2005 21:57:32 +0100, BOOGIEMAN (let's say C#). Can you make fullscreen game with it (for example) ? RANT You can but please don't! Make your game run fast in a window. I hate fascist games programmers who insist on monopolising a 21 inch 1600x1200 display and assuming I have nothing better to do than play their game. If that's all I wanted to do I'd stick with DOS, or buy a Nintendo... I have a multi tasking PC please let me multi task! /RANT ;-) Alan G. Author of the Learn to Program website http://www.freenetpages.co.uk/hp/alan.gauld -- http://mail.python.org/mailman/listinfo/python-list
Re: Approximating scattered data
Grant Edwards wrote: I've been looking for some way to approximate scattered 3D data points in Python. The data doesn't seem to be amenable to fitting functions like polymials, so I may have to use something more like a spline surface. However, I can't find anything usable from Python, and my Fortram skills are pretty rusty. I tried SciPy, but it's spline fitting module doesn't work at all for my data. I've found mentions of a Python port NURBS toolbox, but all the links I can find are broken. NURBS is available in Matlab and Scilab at http://www.aria.uklinux.net/nurbs.php3 , and translating to Python with Numeric/Numarray should not be too hard. If you are trying to fit z = f(x,y) without having a particular functional form in mind, you can apply a nonparametric regression technique. One of the easiest approaches to code is Nadaraya-Watson kernel regression -- see for example http://www.quantlet.com/mdstat/scripts/spm/html/spmhtmlnode24.html , equation 4.68, where a Gaussian kernel can be used for K. PyML at http://pyml.sourceforge.net/doc/tutorial/tutorial.html may implement this (I have not tried it). LIBSVM at http://www.csie.ntu.edu.tw/~cjlin/libsvm/ has a Python interface for Support Vector Machines, a fairly popular and recent flexible regression method. -- http://mail.python.org/mailman/listinfo/python-list
Re: The Industry choice
[EMAIL PROTECTED] writes: Overall I agree with you and would like to have OPTIONAL static type declarations in Python, as has often been discussed. But without facilities for generic programming, such as templates in C++, static type declarations can force one to duplicate a LOT of code, with one sorting routine each for integer, floats, strings, etc. I don't see that big a problem. The current Python sorting routine operates on instances of class object and calls the __cmp__ method to do comparisons. Every class of sortable objects either defines a __cmp__ method or inherits one from some superclass, and sort calls those methods. Static type declarations would not require writing any additional sorting routines. -- http://mail.python.org/mailman/listinfo/python-list
Re: Red Robin Jython JDK classes
Henri Sivonen a écrit : I am trying to set up the Red Robin Jython Development Tools for Eclipse. It finds the Python libraries of Jython and my own jars. It does not find the JDK classes. If I try to add classes.jar from the JDK to the Jython Class Path of the project, the plug-in no longer finds even my own Java classes. How do I make the plug-in see the JDK classes? I am using Eclipse 3.0.1, Mac OS X 10.3.7, Java 1.4.2_05, Jython 2.1 and Red Robin Jython Development Tools 1.3.9. if i may ask, did you ask the author of the eclipse plugin ? did anybody else answer you ? or could you by any chance, solve it by yourself ? -- http://mail.python.org/mailman/listinfo/python-list
PEP 288 ponderings
PEP 288 was mentioned in one of the lambda threads and so I ended up
reading it for the first time recently. I definitely don't like the
idea of a magical __self__ variable that isn't declared anywhere. It
also seemed to me like generator attributes don't really solve the
problem very cleanly. An example from the PEP[1]:
def mygen():
while True:
print __self__.data
yield None
g = mygen()
g.data = 1
g.next()# prints 1
g.data = 2
g.next()# prints 2
I looked in the archives but couldn't find a good discussion of why
setting an attribute on the generator is preferable to passing the
argument to next. Isn't this example basically equivalent to:
class mygen(object):
def next(self, data):
print data
return None
g = mygen()
g.next(1) # prints 1
g.next(2) # prints 2
Note that I didn't even define an __iter__ method since it's never used
in the example.
Another example from the PEP:
def filelike(packagename, appendOrOverwrite):
data = []
if appendOrOverwrite == 'w+':
data.extend(packages[packagename])
try:
while True:
data.append(__self__.dat)
yield None
except FlushStream:
packages[packagename] = data
ostream = filelike('mydest','w')
ostream.dat = firstdat; ostream.next()
ostream.dat = firstdat; ostream.next()
ostream.throw(FlushStream)
This could be rewritten as:
class filelike(object):
def __init__(self, packagename, appendOrOverwrite):
self.data = []
if appendOrOverwrite == 'w+':
self.data.extend(packages[packagename])
def next(self, dat):
self.data.append(dat)
return None
def close(self):
packages[packagename] = self.data
ostream = filelike('mydest','w')
ostream.next(firstdat)
ostream.next(firstdat)
ostream.close()
So, I guess I have two questions:
(1) What's the benefit of the generator versions of these functions over
the class-based versions?
(2) Since in all the examples there's a one-to-one correlation between
setting a generator attribute and calling the generator's next function,
aren't these generator attribute assignments basically just trying to
define the 'next' parameter list?
If this is true, I would have expected that a more useful idiom would
look something like:
def mygen():
while True:
data, = nextargs()
print data
yield None
g = mygen()
g.next(1) # prints 1
g.next(2) # prints 2
where the nextargs function retrieves the arguments of the most recent
call to the generator's next function.
With a little sys._getframe hack, you can basically get this behavior now:
py class gen(object):
... def __init__(self, gen):
... self.gen = gen
... def __iter__(self):
... return self
... def next(self, *args):
... return self.gen.next()
... @staticmethod
... def nextargs():
... return sys._getframe(2).f_locals['args']
...
py def mygen():
... while True:
... data, = gen.nextargs()
... print data
... yield None
...
py g = gen(mygen())
py g.next(1)
1
py g.next(2)
2
Of course, it's still a little magical, but I think I like it a little
better because you can see, looking only at 'mygen', when 'data' is
likely to change value...
Steve
[1] http://www.python.org/peps/pep-0288.html
--
http://mail.python.org/mailman/listinfo/python-list
Re: Confusion About Classes
Well, I took a short excursion into xml for a different part of the
program, but the class is now finished!! (source below) I have a few
more questions for you guys.
1)If I set
self.serverConfig = file(os.path.join('configuration','score.conf'),
'w')
and then go self.serverConfig.close(), is there a way to open it in
read mode without calling the filename directly? Like
self.serverConfig.open('r') -which doesn't work BTW- instead of
open(os.path.join('configuration','score.conf'), 'r')? Using
open(self.ServerConfig, 'r') doesn't seem to work either.
2) A problem arose when converting the encoded file back into a string
for decoding; the \n's seemed to have dissapeared so it returned an
error when I tried to decode. Is there a way to stop python from
disposing of those those characters before writing to file?
3) Is there way to retrieve the timestamp of a file via ftp?
There are NAMES, thats why there are NAMESPACES.
A name is just a reference or 'handle' to an object, because.
everything in python is an OBJECT,(except for names, they are just
names).
And
That being said, understanding this part of Python can aid enormously
in
working with the language. If you'd like to think of it in C terms,
basically every 'name' in Python is a pointer to a PyObject, and
'names'
(as pointers) are always passed by value -- that is, you get a copy
of
the pointer, but not a copy of the object.
Ah...now *that* makes sense. So dynamically typed variables aren't
variables at all...but just another term for pointers? cool, I like
that. And thanks for the examples, guys. Its coming together and I'm
starting to actually 'get it' :)
So name mangling basically follows the rules of private and public in
Java? (I have limited experience in java so don't quote me on that.)
(Google groups isn't displaying the spaces correctly, so I added four
*'s = 1 four space indentation..)
import ftplib, ezPyCrypto, ConfigParser
import traceback, sys, os
#---
class create_server:
'''Create a create_server object whenever a new server is to be
added to
the SCORE network.'''
def __init__(self, absCFGpath, domain, servername, master_ftpUSER,
master_ftpPASS, score_ftpUSER='anonymous',
score_ftpPASS='anonymous',
scorecontact='[EMAIL PROTECTED]', maxusers='unlimited',
httpport='80',
ftpport='21', passivemode=True):
self.domain = domain
self.httpport = httpport
self.ftpport= ftpport
self.servername = servername
self.maxusers = maxusers
self.scorecontact = scorecontact
try:
self.serverConfig =
file(os.path.join('configuration','score.conf'), 'w')
except:
os.mkdir('configuration')
self.serverConfig =
file(os.path.join('configuration','score.conf'), 'w')
self.absCFGpath= absCFGpath
self.master_ftpUSER= master_ftpUSER
self.master_ftpPASS= master_ftpPASS
self.score_ftpUSER = score_ftpUSER
self.score_ftpPASS = score_ftpPASS
self.passivemode = passivemode
self.parser= ConfigParser.ConfigParser()
#---
def createUniversalConfig(self):
'''Creates the SCORE servers main configuration file.'''
self.parser.add_section('score')
self.parser.set('score', 'domain', self.domain)
self.parser.set('score', 'servername', self.servername)
self.parser.set('score', 'httpport', self.httpport)
self.parser.set('score', 'ftpport', self.ftpport)
self.parser.set('score', 'maxusers', self.maxusers)
self.parser.set('score', 'scorecontact', self.scorecontact)
self.parser.write(self.serverConfig)
self.serverConfig.close()
return open(os.path.join('configuration','score.conf'), 'r')
#---
def editUniversalConfig(self, section, key, value):
'''edit the SCORE servers main configuration file.'''
self.serverConfig =
open(os.path.join('configuration','score.conf'), 'w')
self.parser.set(section, key, value)
self.serverConfig.close
#---
def createUSERfile(self):
'''Creates an encrypted ascii public ftp password file that
clients use
to decode after logging in'''
crypt = ezPyCrypto.key()
userFile = file(os.path.join('configuration','uFile.enc'), 'w')
userFile.write(crypt.encStringToAscii(self.score_ftpUSER))
userFile.close()
userFile = open(os.path.join('configuration','uFile.enc'), 'r')
return userFile
#---
def createPASSfile(self):
Re: What can I do with Python ??
On Sat, 01 Jan 2005 16:03:08 -0500, Mark Nenadov wrote: What can you do with Python? Just about anything your heart desires. Thanks everybody, I downloaded latest windows version and Python-Docs-2.4 archive. Is that enough for absolute beginner. Is there any e-book, step by step guide ... etc for download, or anything else important what I have to know before I start learning Python ? -- http://mail.python.org/mailman/listinfo/python-list
Re: What can I do with Python ??
BOOGIEMAN wrote: Thanks everybody, I downloaded latest windows version and Python-Docs-2.4 archive. Is that enough for absolute beginner. Is there any e-book, step by step guide ... etc for download, or anything else important what I have to know before I start learning Python ? The main thing I would do is subscribe to the python-tutor list. It is the best place by far to ask any questions when you are learning to use python: http://mail.python.org/mailman/listinfo/tutor Second, here are some of the best tutorials specifically designed for people with little or no previous programming experience: http://www.honors.montana.edu/~jjc/easytut/easytut/ http://www.freenetpages.co.uk/hp/alan.gauld/ http://www.dickbaldwin.com/tocpyth.htm http://www.ibiblio.org/obp/pyBiblio/ And lastly, really a great way to learn is to look at what's already out there in python. Try out some of the many 3rd party libraries and programs for python: For games: http://pygame.org/ For GUI applications: http://www.wxpython.org/ and others: http://www.python.org/pypi -- http://mail.python.org/mailman/listinfo/python-list
Re: Is it possible to open a dbf
Paul Rubin wrote: John Fabiani [EMAIL PROTECTED] writes: I'm wondering if there is a module available that will open a dbf So far (more than a minute) I have discovered a reader only. So if you have a URL or a search string it would be very helpful. TIA John Yes, dBase Python yields only some code for reading dBase ... and lots of enquires about such a thing... Miklós --- Jegenye 2001 Bt. Egyedi szoftverkészítés, tanácsadás | Custom software development, consulting Magyarul: http://jegenye2001.parkhosting.com In English: http://jegenye2001.parkhosting.com/en -- http://mail.python.org/mailman/listinfo/python-list
Re: PEP 288 ponderings
On Sun, 02 Jan 2005 01:04:06 GMT, Steven Bethard [EMAIL PROTECTED] wrote: PEP 288 was mentioned in one of the lambda threads and so I ended up reading it for the first time recently. I definitely don't like the idea of a magical __self__ variable that isn't declared anywhere. It also seemed to me like generator attributes don't really solve the problem very cleanly. An example from the PEP[1]: [snip] You may be interested in greenlets. They solve this problem in a way which is conceptually much simpler and cleaner. They are available as a third party extension, and unfortunately are not terribly well documented yet (but luckily they are quite simple). http://codespeak.net/svn/user/arigo/greenlet/ Jp -- http://mail.python.org/mailman/listinfo/python-list
screen clear question
Is there a command in Python to clear the screen? That is without writing multiple blank lines. Thanks. Jim C -- http://mail.python.org/mailman/listinfo/python-list
ANN: PyXR 0.9.4 - Cross-Referenced HTML from Python Source
PyXR 0.9.4 - Cross-Referenced HTML from Python Source PyXR generates pretty-printed HTML pages from python source files to make source browsing easier. It provides extensive cross-referencenced hyperlinks that integrate with the Python Library Reference as well as other python source files. Its cross-referencing capabilities are vastly superior to other source pretty-printing packages that I've seen. 0.9.4 provides compatibility with the new language semantics in Python 2.4 and addresses changes to the format of the Library Reference Manual, in addition to a littany of smaller fixes. Previous versions WILL NOT work with python 2.4. This release does provide backward compatibility to python versions as early as 2.2 and should work on all major OSes. PyXR is available for download here: http://sourceforge.net/projects/pyxr/ PyXR'ed markup of Python 2.4's source is available here: http://pyxr.sourceforge.net/PyXR/ Detailed release notes are available here: http://pyxr.sourceforge.net/ Enjoy! -- http://mail.python.org/mailman/listinfo/python-list
HTTP GET request with basic authorization?
How do I do this using httplib.HTTPConnection and
httplib.HTTPConnection.request()? The library reference only gives a
simple GET example with no header stuff. I tried this, but it didn't work:
conn.request(GET, /somepage.html, None, {AUTHORIZATION: Basic
username:password})
Thanks for the help.
P.S. I know nothing about HTTP, I'm just piecing this stuff together from
examples on the internet, please be gentle with your responses.
--
http://mail.python.org/mailman/listinfo/python-list
Re: Mailing list hosting?
free mailing list offer - limited time http://nabaza.com/autoresponders.htm -- http://mail.python.org/mailman/listinfo/python-list
Re: OT: spacing of code in Google Groups
Terry Reedy schreef: JanC [EMAIL PROTECTED] wrote in message news:[EMAIL PROTECTED] I don't know if gmane keeps formating of messages intact when posting? That could be an alternative too... Reading posts via gmane with Outlook Express preserves leading spaces just fine. However, OE deletes tabs regardless of what newsgroup does. OE is useless anyway (at least as a newsreader). I was talking about the gmane web interface as an alternative to Google's. They have an NNTP server but also three http-based interfaces: RSS-feed, blog-style framed (looks more or less like a newsreader). ... Tested it in gmane.test, posting through their web interface preserves whitespace. -- JanC Be strict when sending and tolerant when receiving. RFC 1958 - Architectural Principles of the Internet - section 3.9 -- http://mail.python.org/mailman/listinfo/python-list
Frameworks for Non-Content Oriented Web Apps
Hi, There are great Python Web Application Framework. But most of them are meant for content oriented web apps. Is there something that can ease the development of application that are not content oriented(I call them NON CONTENT-ORIENTED WEB APPLICATIONS because I don't know what else to call them). I mean the applications like, accounting, high volume data entry apps, where normally GUI clients have ruled. I know very high quality ERP and similar packages have been implemented in a web based environment. But problem is that they have been developed with the tools that were actually meant for content oriented apps like Zope, PHP, etc. But is there some sort of framework or something that is actually meant for such web apps,application that make heavy use of forms, have very high amount of user interaction etc. What I am asking here may sound off beat, but I think, in todays world where web based solutions offers such a flexibility, we really need it. I also know that I am to ambiguous, but as is the characteristic of this wonderful community, talks that start as most abigous, transform in crystal clear. PS: I am a web developer, using PHP for living. I have been playing with python for a while. I found python is really a cool language(do I need to say that ;-)) with a really, really impressive collection of modules and frameworks. While developing a school information system, I felt the need of such a framework that makes developing of Non-Content Oriented Web-Apps easy. I know I posted a similar message earlier, but this time I a bit more general. -- http://mail.python.org/mailman/listinfo/python-list
Re: Frameworks for Non-Content Oriented Web Apps
[EMAIL PROTECTED] wrote: Hi, There are great Python Web Application Framework. But most of them are meant for content oriented web apps. Is there something that can ease the development of application that are not content oriented(I call them NON CONTENT-ORIENTED WEB APPLICATIONS because I don't know what else to call them). I mean the applications like, accounting, high volume data entry apps, where normally GUI clients have ruled. I know very high quality ERP and similar packages have been implemented in a web based environment. But problem is that they have been developed with the tools that were actually meant for content oriented apps like Zope, PHP, etc. Can you give some URL for publicly accessible examples of what you mean by a NON CONTENT-ORIENTED WEB APPLICATIONS, so we can get a better idea of what you mean? Tim C -- http://mail.python.org/mailman/listinfo/python-list
Re: Frameworks for Non-Content Oriented Web Apps
Tim Churches [EMAIL PROTECTED] writes: Can you give some URL for publicly accessible examples of what you mean by a NON CONTENT-ORIENTED WEB APPLICATIONS, so we can get a better idea of what you mean? I don't think there was anything unclear about it. A spreadsheet might be a good example. -- http://mail.python.org/mailman/listinfo/python-list
Re: when wxPython update to python2.4?
alang_yl wrote: i can't wait. wxPython 2.5 already has a version which works with Python 2.4 (grab it from www.wxpython.org). For the wxPython 2.4 series, I understand Robin is planning a release which will both integrate the 2.4 series into the new wxPython versioning scheme, and also include a Python 2.4 compatible version. The timeframe for that isn't entirely clear, though. Cheers, Nick. -- Nick Coghlan | [EMAIL PROTECTED] | Brisbane, Australia --- http://boredomandlaziness.skystorm.net -- http://mail.python.org/mailman/listinfo/python-list
Re: Frameworks for Non-Content Oriented Web Apps
[EMAIL PROTECTED] wrote: But is there some sort of framework or something that is actually meant for such web apps,application that make heavy use of forms, have very high amount of user interaction etc. Hmm, PJE's PEAK might be worth having a look at: http://peak.telecommunity.com/ However, I'm not sure if that will provide enough of the 'web' side of things. Cheers, Nick. -- Nick Coghlan | [EMAIL PROTECTED] | Brisbane, Australia --- http://boredomandlaziness.skystorm.net -- http://mail.python.org/mailman/listinfo/python-list
Re: The Industry choice
Paul Rubin wrote: I don't see that big a problem. The current Python sorting routine operates on instances of class object and calls the __cmp__ method to do comparisons. Every class of sortable objects either defines a __cmp__ method or inherits one from some superclass, and sort calls those methods. Static type declarations would not require writing any additional sorting routines. Python's list.sort doesn't check the *type* of the arguments at all. It only looks for the relevant comparison methods (__cmp__ or __lt__, as I recall). Sure, classes written in *Python* will ultimately inherit from either object or types.ClassType, but extension classes need not do any such thing. Yet list.sort works with them all, anyway. Cheers, Nick. -- Nick Coghlan | [EMAIL PROTECTED] | Brisbane, Australia --- http://boredomandlaziness.skystorm.net -- http://mail.python.org/mailman/listinfo/python-list
Re: screen clear question
On Sun, 2005-01-02 at 11:31, jcollins wrote: Is there a command in Python to clear the screen? That is without writing multiple blank lines. Without knowing what 'screen' you're talking about, it's hard to say. If you mean clearing a terminal, you can call 'tput clear' or '/usr/bin/clear' on many UNIX systems; no idea about Windows. -- Craig Ringer -- http://mail.python.org/mailman/listinfo/python-list
Re: PEP 288 ponderings
Steven Bethard wrote: PEP 288 was mentioned in one of the lambda threads and so I ended up reading it for the first time recently. I definitely don't like the idea of a magical __self__ variable that isn't declared anywhere. It also seemed to me like generator attributes don't really solve the problem very cleanly. An example from the PEP[1]: def mygen(): while True: print __self__.data yield None g = mygen() g.data = 1 g.next()# prints 1 g.data = 2 g.next()# prints 2 I don't get why this isn't good enough: def mygen(data): while True: print data[0] yield None data = [None] g = mygen(data) data[0] = 1 g.next() data[0] = 1 g.next() Using a one-element list is kind of annoying, because it isn't clear out of context that it's just a way of creating shared state. But it's okay, work right now, and provides the exact same functionality. The exception part of PEP 288 still seems interesting. -- Ian Bicking / [EMAIL PROTECTED] / http://blog.ianbicking.org -- http://mail.python.org/mailman/listinfo/python-list
Re: The Industry choice
Quoth Paul Rubin http://[EMAIL PROTECTED]: | [EMAIL PROTECTED] writes: | Overall I agree with you and would like to have OPTIONAL static type | declarations in Python, as has often been discussed. But without | facilities for generic programming, such as templates in C++, static | type declarations can force one to duplicate a LOT of code, with one | sorting routine each for integer, floats, strings, etc. | | I don't see that big a problem. The current Python sorting routine | operates on instances of class object and calls the __cmp__ method | to do comparisons. Every class of sortable objects either defines a | __cmp__ method or inherits one from some superclass, and sort calls | those methods. Static type declarations would not require writing any | additional sorting routines. Yes, it would be really weird if Python went that way, and the sort of idle speculations we were reading recently from Guido sure sounded like he knows better. But it's not like there aren't some interesting issues farther on downstream there, in the compare function. cmp(), and str() and so forth, play a really big role in Python's dynamically typed polymorphism. It seems to me they are kind of at odds with static type analysis, especially if you want type inference -- kind of a type laundering system, where you can't tell what was supposed to be there by looking at the code. Some alternatives would be needed, I suppose. Donn Cave, [EMAIL PROTECTED] -- http://mail.python.org/mailman/listinfo/python-list
Re: Frameworks for Non-Content Oriented Web Apps
[EMAIL PROTECTED] wrote: There are great Python Web Application Framework. But most of them are meant for content oriented web apps. Is there something that can ease the development of application that are not content oriented(I call them NON CONTENT-ORIENTED WEB APPLICATIONS because I don't know what else to call them). Maybe you mean interactive web applications, as opposed to document-centric applications? But then, that's what most frameworks are really designed for. I mean the applications like, accounting, high volume data entry apps, where normally GUI clients have ruled. I know very high quality ERP and similar packages have been implemented in a web based environment. But problem is that they have been developed with the tools that were actually meant for content oriented apps like Zope, PHP, etc. Zope I'd say is content-oriented, though with a bit of imagination you can phrase these applications in terms of content. PHP and many other Python frameworks are process-oriented, meaning that each request just plain executes some code. Which is true of Zope too, but the basic metaphors in Zope are that a request displays the view of some object, which is a little more abstract way of looking at it. But is there some sort of framework or something that is actually meant for such web apps,application that make heavy use of forms, have very high amount of user interaction etc. Do you mean non-traditional web applications, ala gmail? Probably not, I think you are talking about certain framework concerns that most frameworks aspire to in some fashion, but actually achieve to differing degrees. PEAK addresses some of these, but in a UI-neutral way, and it's quite experimental (at least in the perspective of a whole application; as robust as the individual pieces may be, there's no real model for how to use it for a full application). There's other form processing libraries, but they all are experimental in a way. I developed FormEncode, which relates to some of this. Zope 3 has Schemas, which can be used for form generation and validation, and Plone has Archetypes. I don't think there's anything that's a Whole Package, but Zope 3 and Plone/Archetypes might be the closest (depending on what your vision is). What I am asking here may sound off beat, but I think, in todays world where web based solutions offers such a flexibility, we really need it. I also know that I am to ambiguous, but as is the characteristic of this wonderful community, talks that start as most abigous, transform in crystal clear. PS: I am a web developer, using PHP for living. I have been playing with python for a while. I found python is really a cool language(do I need to say that ;-)) with a really, really impressive collection of modules and frameworks. While developing a school information system, I felt the need of such a framework that makes developing of Non-Content Oriented Web-Apps easy. Eh, it just needs some clear direction for *any* kind of web apps, IMHO. But with what you are specifically asking for, I think it's just a Hard Problem that Is Not Yet Solved, though there is work being done and people are attacking it from different directions. -- Ian Bicking / [EMAIL PROTECTED] / http://blog.ianbicking.org -- http://mail.python.org/mailman/listinfo/python-list
Re: Any Python XML Data Binding Utilities Avaiable?
Sounds like generateDS is closest to what you want: http://www.rexx.com/~dkuhlman/generateDS.html If you can bind from instances only and don't need schema, see Amara Bindery: http://uche.ogbuji.net/tech/4Suite/amara/ Also consider Gnosis Utilities and ElementTree. -- Uche OgbujiFourthought, Inc. http://uche.ogbuji.nethttp://4Suite.orghttp://fourthought.com Use CSS to display XML - http://www.ibm.com/developerworks/edu/x-dw-x-xmlcss-i.html Full XML Indexes with Gnosis - http://www.xml.com/pub/a/2004/12/08/py-xml.html Be humble, not imperial (in design) - http://www.adtmag.com/article.asp?id=10286UBL 1.0 - http://www-106.ibm.com/developerworks/xml/library/x-think28.html Use Universal Feed Parser to tame RSS - http://www.ibm.com/developerworks/xml/library/x-tipufp.html Default and error handling in XSLT lookup tables - http://www.ibm.com/developerworks/xml/library/x-tiplook.html A survey of XML standards - http://www-106.ibm.com/developerworks/xml/library/x-stand4/ The State of Python-XML in 2004 - http://www.xml.com/pub/a/2004/10/13/py-xml.html -- http://mail.python.org/mailman/listinfo/python-list
Re: screen clear question
import os # windows os.system(cls) # bash ( mac, linux ) os.system(clear) That's all I can account for. Daniel Bickett -- http://mail.python.org/mailman/listinfo/python-list
Re: Frameworks for Non-Content Oriented Web Apps
On 1 Jan 2005 20:51:06 -0800, [EMAIL PROTECTED] [EMAIL PROTECTED] wrote: But is there some sort of framework or something that is actually meant for such web apps,application that make heavy use of forms, have very high amount of user interaction etc. etc Yeah, nevow, by those crazy twisted people, is great. The underlying concept is 'object publishing', and has some very funky technology for live-updating of a client-side web page via javascript (ala gmail). Object publishing is along the lines of, instead of having a 'form', you have an object which represents data. It knows how to handle form submissions, validate data, etc. And you 'publish' that object. The user can then interact with that object. Anyway, I haven't mucked around with nevow for months, you're better off checking out nevow.com and divmod.org yourself. Stephen. -- http://mail.python.org/mailman/listinfo/python-list
Re: The Industry choice
Donn Cave [EMAIL PROTECTED] writes: Yes, it would be really weird if Python went that way, and the sort of idle speculations we were reading recently from Guido sure sounded like he knows better. But it's not like there aren't some interesting issues farther on downstream there, in the compare function. cmp(), and str() and so forth, play a really big role in Python's dynamically typed polymorphism. It seems to me they are kind of at odds with static type analysis I don't understand that. If I see str x = str(3), then I know that x is a string. -- http://mail.python.org/mailman/listinfo/python-list
Re: PEP 288 ponderings
Ian Bicking wrote: Using a one-element list is kind of annoying, because it isn't clear out of context that it's just a way of creating shared state. But it's okay, work right now, and provides the exact same functionality. Uh, isn't shared state what classes were invented for? Py class mygen(object): ... def __init__(self, data): ... self.data = data ... def __iter__(self): ... while 1: ... print self.data ... yield None ... Py g = mygen(0) Py giter = iter(g) Py giter.next() 0 Py g.data = 1 Py giter.next() 1 Cheers, Nick. -- Nick Coghlan | [EMAIL PROTECTED] | Brisbane, Australia --- http://boredomandlaziness.skystorm.net -- http://mail.python.org/mailman/listinfo/python-list
[ python-Bugs-1092502 ] Memory leak in socket.py on Mac OS X 10.3
Bugs item #1092502, was opened at 2004-12-28 21:09
Message generated for change (Comment added) made by etrepum
You can respond by visiting:
https://sourceforge.net/tracker/?func=detailatid=105470aid=1092502group_id=5470
Category: Python Library
Group: Platform-specific
Status: Open
Resolution: None
Priority: 5
Submitted By: bacchusrx (bacchusrx)
Assigned to: Nobody/Anonymous (nobody)
Summary: Memory leak in socket.py on Mac OS X 10.3
Initial Comment:
Some part of socket.py leaks memory on Mac OS X 10.3 (both with
the python 2.3 that ships with the OS and with python 2.4).
I encountered the problem in John Goerzen's offlineimap.
Transfers of messages over a certain size would cause the program
to bail with malloc errors, eg
*** malloc: vm_allocate(size=5459968) failed (error code=3)
*** malloc[13730]: error: Can't allocate region
Inspecting the process as it runs shows that python's total memory
size grows wildly during such transfers.
The bug manifests in _fileobject.read() in socket.py. You can
replicate the problem easily using the attached example with nc -l
-p 9330 /dev/zero running on some some remote host.
The way _fileobject.read() is written, socket.recv is called with the
larger of the minimum rbuf size or whatever's left to be read.
Whatever is received is then appended to a buffer which is joined
and returned at the end of function.
It looks like each time through the loop, space for recv_size is
allocated but not freed, so if the loop runs for enough iterations,
python exhausts the memory available to it.
You can sidestep the condition if recv_size is small (like
_fileobject.default_bufsize small).
I can't replicate this problem with python 2.3 on FreeBSD 4.9 or
FreeBSD 5.2, nor on Mac OS X 10.3 if the logic from
_fileobject.read() is re-written in Perl (for example).
--
Comment By: Bob Ippolito (etrepum)
Date: 2005-01-01 21:25
Message:
Logged In: YES
user_id=139309
that code paste is missing an int i at the beginning of main..
--
Comment By: Bob Ippolito (etrepum)
Date: 2005-01-01 21:23
Message:
Logged In: YES
user_id=139309
#include unistd.h
#define NUM_ALLOCATIONS 10
#define ALLOC_SIZE 10485760
#define ALLOC_RESIZE 1492
int main(int argc, char **argv) {
/* exiting will free all this leaked memory */
for (i = 0; i NUM_ALLOCATIONS; i++) {
void *orig_ptr, *new_ptr;
size_t new_size, orig_size;
orig_ptr = malloc(ALLOC_SIZE);
orig_size = malloc_size(orig_ptr);
if (orig_ptr == NULL) {
printf(failure to malloc %d\n, i);
abort();
}
new_ptr = realloc(orig_ptr, ALLOC_RESIZE);
new_size = malloc_size(new_ptr);
printf(resized %d[%p] - %d[%p]\n,
orig_size, orig_ptr, new_size, new_ptr);
if (new_ptr == NULL) {
printf(failure to realloc %d\n, i);
abort();
}
}
return 0;
}
--
Comment By: Bob Ippolito (etrepum)
Date: 2005-01-01 21:22
Message:
Logged In: YES
user_id=139309
Ok. I've tracked it down. realloc(...) on Darwin doesn't actually resize
memory unless it *has* to. For shrinking an allocation, it does not have
to, therefore realloc(...) with a smaller size is a no-op.
It seems that this may be a misunderstanding by Python. The man page
for realloc(...) does not say that it will EVER free memory, EXCEPT in the
case where it has to allocate a larger region.
I'll attach an example that demonstrates this outside of Python.
--
Comment By: bacchusrx (bacchusrx)
Date: 2005-01-01 18:01
Message:
Logged In: YES
user_id=646321
I've been able to replicate the problem reliably on both 10.3.5 and
10.3.7. I've attached two more examples to demonstrate:
Try this: Do, dd if=/dev/zero of=./data bs=1024 count=10240 and save
server.pl wherever you put data. Have three terminals open. In one,
run perl server.pl -s0.25. In another, run top -ovsize and in the third
run python example2.py.
After about 100 iterations, python's vsize is +1GB (just about the value
of cumulative_req in example2.py) and if left running will cause a
malloc error at around 360 iterations with a vsize over 3.6GB (again, just
about what cumulative_req reports). Mind you, we've only received
~512kbytes.
server.pl differs from the netcat method in that it (defaults) to sending
only 1492 bytes at a time (configurable with the -b switch) and sleeps for
however many seconds specified with the -s switch. This guarantees
enough iterations to raise the error each time around. When omittting
the -s switch to server.pl, I don't get the error, but throughput is good
enough that the loop in readFromSockUntil() only runs a few times.
