Reading Windows CSV file with LCID entries under Linux.
Dear all, I've stumbled over a problem with Windows Locale ID information and codepages. I'm writing a Python application that parses a CSV file, the format of a line in this file is LCID;Text1;Text2. Each line can contain a different locale id (LCID) and the text fields contain data that is encoded in some codepage which is associated with this LCID. My current data file contains the codes 1033 for German and 1031 for English US (as listed in http://www.microsoft.com/globaldev/reference/lcid-all.mspx). Unfortunately, I cannot find out which Codepage (like cp-1252 or whatever) belongs to which LCID. My question is: How can I convert this data into something more reasonable like unicode? Basically, what I want is something like Text1;Text2, both fields encoded as UTF-8. Can this be done with Python? How can I find out which codepage I have to use for 1033 and 1031? Any help appreciated, Thomas. -- http://mail.python.org/mailman/listinfo/python-list
Re: Difference between type and class
Steven D'Aprano wrote: class A: def bar(self): print A Alas, you've chosen the worst-possible example to clarify matters, because old-style classic classes are *not* unified with types, and will disappear in the future: Of course I wanted to write `class A(object)', but I keep forgetting this one because I'm still used to the old ways... Will this disappear in Python 3.0., i.e. can you again simply write class A: and inherit from object automagically? That would be nice since that's what most people probably want. -- http://mail.python.org/mailman/listinfo/python-list
Re: Difference between type and class
Can someone explain to me the difference between a type and a class? If your confusion is of a more general nature I suggest reading the introduction of `Design Patterns' (ISBN-10: 0201633612), under `Specifying Object Interfaces'. In short: A type denotes a certain interface, i.e. a set of signatures, whereas a class tells us how an object is implemented (like a blueprint). A class can have many types if it implements all their interfaces, and different classes can have the same type if they share a common interface. The following example should clarify matters: class A: def bar(self): print A class B: def bar(self): print B class C: def bla(self): print C def foo(x): x.bar() you can call foo with instances of both A and B, because both classes share a common type, namely the type that has a `bar' method), but not with an instance of C because it has no method `bar'. Btw, this example shows the use of duck typing (http://en.wikipedia.org/wiki/Duck_typing). HTH, Thomas. -- http://mail.python.org/mailman/listinfo/python-list
Re: Difference between type and class
That would imply that I cannot create instances of a type, only of a class that implements the type, wouldn't it? But Python denotes 'int' as a type *and* I can instantiate it. Now I start getting confused also ;-) a=5 a.__class__ type 'int' a.__class__.__class__ type 'type' dir(a) ['__abs__', '__add__', '__and__', '__class__', '__cmp__', '__coerce__', '__delattr__', '__div__', '__divmod__', '__doc__', '__float__', '__floordiv__', '__getattribute__', '__getnewargs__', '__hash__', '__hex__', '__index__', '__init__', '__int__', '__invert__', '__long__', '__lshift__', '__mod__', '__mul__', '__neg__', '__new__', '__nonzero__', '__oct__', '__or__', '__pos__', '__pow__', '__radd__', '__rand__', '__rdiv__', '__rdivmod__', '__reduce__', '__reduce_ex__', '__repr__', '__rfloordiv__', '__rlshift__', '__rmod__', '__rmul__', '__ror__', '__rpow__', '__rrshift__', '__rshift__', '__rsub__', '__rtruediv__', '__rxor__', '__setattr__', '__str__', '__sub__', '__truediv__', '__xor__'] I think in Python everything is implemented as a class which makes sense. AFAIK you can implement a certain interface in a custom class and it behaves like, for example, a builtin integer. But I guess one of the gurus can clarify this matter with an appropriate URL ;-) -- http://mail.python.org/mailman/listinfo/python-list
Re: Function editing with Vim throws IndentError
Lawrence D'Oliveiro wrote: Specified by whom? The most common setting these days is 4 columns. Where? I've randomly seen code snipplets that indent using spaces or, worse, tabstop != 8, but most code I've come across uses tabstop width 8, which is how it was meant to be from the beginning of time. Unfortunately, for many people it's hard to understand that a tabstop is not the same as indenting with spaces, but I think this is leading too far and will end in a dogmatic discussion like the `ViM vs. Emacs' war. Anyways, if you claim tabstop 4 is most widely used I'd like to see some kind of a reference for that since it contradicts not only my experience. Finally, I'd like to throw in this one from the Linux kernel sources, from `Documentation/CodingStyle: Chapter 1: Indentation Tabs are 8 characters, and thus indentations are also 8 characters. There are heretic movements that try to make indentations 4 (or even 2!) characters deep, and that is akin to trying to define the value of PI to be 3. [...] Now, some people will claim that having 8-character indentations makes the code move too far to the right, and makes it hard to read on a 80-character terminal screen. The answer to that is that if you need more than 3 levels of indentation, you're screwed anyway, and should fix your program. In short, 8-char indents make things easier to read, and have the added benefit of warning you when you're nesting your functions too deep. Heed that warning. -- http://mail.python.org/mailman/listinfo/python-list
Re: Function editing with Vim throws IndentError
ptn wrote: Hi everybody, I have a weird problem. Say I have a .py file with some functions in it, like this: [...] Could someone provide some pointers? Thanks, Pablo Torres N. Have you enabled the `list' option to see which characters are acutally on the lines of interest? Try out `:set list' and see the contents! Otherwise helpful is `ga' to see the code values. Of course this will not tell you why it is going wrong, but maybe it helps you to determine what is going wrong :-) -- http://mail.python.org/mailman/listinfo/python-list
Re: Python embedding question (2).
Carl Banks wrote: On Jul 17, 9:57 am, Thomas Troeger [EMAIL PROTECTED] wrote: I'd say that PyGame could be a solution. Or otherwise you could do your own audio/graphics programming (you don't tell us which OS you use, but there exist python modules that allow you to do barebones graphics sound programming on linux...). Pyglet runs on top of OpenGL, which might have performance problems on an embedded device, if OpenGL or Mesa is even supported. If it's supported, I suspect performance will be adequate for 2D drawing. It almost certainly is the lightest solution you can find. Carl Banks I've managed to put together a small pyGame program, it runs smoothly and seems to be exactly what I wanted. It's fast! Even with 100 moving objects it still runs so fast that I can consider using Python/pyGame for the whole project. There are still some questions left which I haven't found out by myself, so maybe someone here can answer them: - I can't see how to create more sophisticated text output, it seems the built in font render facilities are limited to simple strings. Is that true? I'd need a way to at least render multiline text with paragraphs and bidirectionality, like pango does it. Is there a way to integrate pango support into pyGame? I'd prefer marked up text display with text properties ... - Is there some way to reserve screen areas so they are excluded from a blit, or do I have to manage stuff like this myself? I am thinking about several graphic layers where each layer is painted on top of the next layer, for example to draw a gui in front of a background image. - There seems to be support for video overlay, i.e. is it possible to have an external program paint an image from a camera into a portion of the screen while pyGame is running? Maybe this is the wrong list to ask, so please forgive the question but direct me to somewhere better. Cheers, Thomas. -- http://mail.python.org/mailman/listinfo/python-list
Re: Using Tcl extensions with Python?
C Martin wrote: How do you setup a Tcl extension to be accessible through Python? I understand that I'll have to use native Tcl calls to use it (tk.call() etc), but I can't figure out where to put the files or how to initialize them so I can call them. The package I would like to use is TkPNG: http://www.muonics.com/FreeStuff/TkPNG/ Thanks. ARGH, Tcl!!! ;-) I know that's not the question, but do you know PIL (http://www.pythonware.com/products/pil)? -- http://mail.python.org/mailman/listinfo/python-list
Re: Python embedding question.
Jan Claeys wrote: I'd say that PyGame could be a solution. Or otherwise you could do your own audio/graphics programming (you don't tell us which OS you use, but there exist python modules that allow you to do barebones graphics sound programming on linux...). Yes, I'm using a very small Linux system with busybox, running from a compact flash drive. I'll investigate PyGame, it sounds as if it is a good candidate :P Thanks so far, Thomas. -- http://mail.python.org/mailman/listinfo/python-list
Re: Python embedding question (2).
I'd say that PyGame could be a solution. Or otherwise you could do your own audio/graphics programming (you don't tell us which OS you use, but there exist python modules that allow you to do barebones graphics sound programming on linux...). After some more reading I've stumbled over pyglet. Any experiences with it? It seems it does a lot of cool things, if anyone has used it more intensely I'd be happy to hear if the following things can be done: - Linux framebuffer (16, 24 bpp) display of 2d graphics with overlays (i.e. menues, contextual areas that pop up etc.). I don't have X on the embedded device, just the regular framebuffer. - alpha blending of several layers. - rendering of TTF fonts and unicode, for example display of arabic text (which renders from right to left) and mixed text support like in the unicode bidirectional algorithm. - hardware caching of bitmaps for faster graphics operations (needed for tool tips or similar tasks). I'll try to find that out myself (I'm pretty excited about the thing already ^^), but I'd be happy to hear of people who have used it already. Cheers, Thomas. -- http://mail.python.org/mailman/listinfo/python-list
Python embedding question.
Hi, Sorry I've posted a similar question some weeks ago, but I got no answers. I want to embed a Python application on a device with limited resources, esp. storage limitations. Is there a way to reduce the Python interpreter to a set of modules that's urgently needed? Or is there a method to have gzipped modules that are unzipped on the fly into memory when they're accessed? That would be even better. Additionally, is there a Python module that contains all the stuff needed for an embedded application like graphics, sound etc. or do I have to use the various bindings to libraries like cairo, Qt or similar? Is there a site that helps with those decisions? I've really looked at a lot of places but haven't found a suitable solutions yet, so I'm asking here in hope that someone has experience with that topic. Regards, Thomas. -- http://mail.python.org/mailman/listinfo/python-list
Re: Testing for Internet Connection
Alex Marandon wrote: Alexnb wrote: I am wondering, is there a simple way to test for Internet connection? If not, what is the hard way :p Trying to fetch the homepage from a few major websites (Yahoo, Google, etc.)? If all of them are failing, it's very likely that the connection is down. You can use urllib2 [1] to accomplish that. [1] http://docs.python.org/lib/module-urllib2.html This seems to work and is rather fast and wastes no bandwidth: == #!/usr/bin/python import socket, struct def check_host(host, port, timeout=1): Check for connectivity to a certain host. # assume we have no route. ret=False # connect to host. try: # create socket. sock=socket.socket() # create timeval structure. timeval=struct.pack(2I, timeout, 0) # set socket timeout options. sock.setsockopt(socket.SOL_SOCKET, socket.SO_RCVTIMEO, timeval) sock.setsockopt(socket.SOL_SOCKET, socket.SO_SNDTIMEO, timeval) # connect to host. sock.connect((host, port)) # abort communications. sock.shutdown(SHUT_RDWR) # we have connectivity after all. ret=True except: pass # try to close socket in any case. try: sock.close() except: pass return ret # main - if check_host(www.heise.de, 80): print Horray! else: print We've lost headquarters! == I hope the code is ok, but there is always something you can do better. Comments? :) Cheers, Thomas. -- http://mail.python.org/mailman/listinfo/python-list
Static Class Initialization Question.
Hello,
I have a class that looks like this:
class A(object):
def __init__(self, a=0, b=1):
self.a, self.b=a, b
def __str__(self):
return %s(%d,%d) % (type(a).__name__, self.a, self.b)
I want to have a list of such classes instantiated automatically on
startup of my program. My current (most probably clumsy) implementation
looks like this:
bla=[A(x[0], x[1]) for x in ((1, 2), (3, 4))]
giving the following:
map(str, bla)
['A(1,2)', 'A(3,4)']
Is there a better way to construct a list of such classes? Basically
what I want is something similar to the following C example:
struct {
int a;
int b;
} bla[]={ {1, 2}, {3, 4} };
Regards,
T.
--
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Re: Static Class Initialization Question.
Bruno Desthuilliers wrote: return %s(%d,%d) % (type(self).__name__, self.a, self.b) Er, yes exactly! I noticed it a few seconds after I had sent the message ;-( I want to have a list of such classes instantiated automatically on Of course I meant class instances ... sorry :) It's always good to have an example to compensate for English errors *g*. bla = [A(*args) for args in ((1,2), (3,4))] ... Note that it's not a list of classes, but a list of instances of A. But given your specs, nope, your approach is the right one. Ah I knew there was something and I couldn't find it in the docs anymore! Now my potential follow-up question is answered as well, namely how I can instantiate with variable argument lists, like this: bla = [A(*args) for args in ((), (1,), (1, 2))] map(str, bla) ['A(0,1)', 'A(1,1)', 'A(1,2)'] Basically (no pun intended[1]), Python is not C. Trying to write C in Python will only buy you pain and frustration (and this can be generalized for any combination of two languages for any known programming language). Hehe. I am trying to develop a program prototype in python because of it's repaid prototyping properties, and once it's working I will port it to C, because of speed issues and the fact that it's running on an embedded machine without space for a python interpreter. I have like 4 Megs left, but until now noone has answered my question how I can cut down a standard python installation so that it fit's into 4 megs. Thanks for your quick answer :) T. -- http://mail.python.org/mailman/listinfo/python-list
Minimal Python installation?
Hi,
I'd like to put the python library and interpreter on a small embedded
Linux x86 compatible device where disk space is an issue. I played
around with the minimal Python interpreters, but was not entirely happy
with them, so my question is, is there an (preferably easy) way to put
the interpreter and a cut-down version of the python library/modules
that ship with regular Python into a new archive that I can safely copy
and use? My current method is to copy the python interpreter and the
python shared library to the device. Then I create a tar archive with
all startup files from the site package directory to my archive using
the following one-liner:
strace -f -eopen python -c 'pass' 21 | grep -v ENO | grep '\.py' | awk
'BEGIN { FS=\ } { print $2 }' | tar cvf x.tar -T -
This effectively packs all python library files that are accessed upon
startup into a tar archive. But I figure this method is not what I want
because there surely are files I am missing here (for example which are
accessed when starting a script), and what I really want is a minimal
environment that works. Let's say I want a complete Python install, but
without all the batteries :-)
Any pointers?
Regards,
Thomas.
--
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Re: compressing short strings?
Paul Rubin wrote: I have a lot of short English strings I'd like to compress in order to reduce the size of a database. That is, I'd like a compression function that takes a string like (for example) George Washington [...] Thanks. I think your idea is good, maybe you'd want to build an LZ78 encoder in Python (LZ78 is pretty easy), feed it with a long English text and then pickle the resulting object. You could then unpickle it on program start and encode your short strings with it. I bet there's a working implementation around that already that does it ... but if you can't find any, LZ78 is implemented in 1 or 2 hours. There was a rather good explanation of the algorithm in German, unfortunately it's vanished from the net recently (I have a backup if you're interested). Cheers, Thomas. -- http://mail.python.org/mailman/listinfo/python-list
Embedding Python question.
Dear all, I've successfully embedded the Python interpreter into a set of C/C++ application programs that use a larger library project with information from http://docs.python.org/api/api.html and http://docs.python.org/ext/ext.html. Now I want to wrap classes and functions from the associated libraries so that I can write new applications completely in Python, but I'm not entirely sure how to start because I have some problems understanding which is the best way. It would be nice if someone could answer the following questions and clarify this matter: - until now I've used the approach as documented in http://docs.python.org/ext/extending-with-embedding.html to extend the embedded interpreter and that works pretty well. I'd like to use a similar approach for other C applications. Can I write a C library that implements this technique and link it into all C applications that need Python support, or is there a better, more elegant way? - in the documentation, there's an example that illustrates the creation of a python module for pure extending of a python script (the Noddy stuff). Do I have to make a separate module for each library I want to wrap? If yes, how can I manage the case where two libraries can access each other? - if I write an extension module, how can I handle the case where the C wrapper methods want to call back into the same Python interpreter instance? - I think my questions break down into a reference to documentation where a similar problem is explained in detail. Does anyone have such information? Thanks! Thomas. -- http://mail.python.org/mailman/listinfo/python-list
Re: Newbie In Python
[EMAIL PROTECTED] wrote: I have Heard About Python its a OOD Language. i have to Learn it where from i should start it. i have python compiler at linux Platform. anyone can suggest me about it. Thanks In advance. How about http://docs.python.org/tut/tut.html? -- http://mail.python.org/mailman/listinfo/python-list
Re: Embedding python code into text document question.
Thanks guys, you've helped me very much :) Cheers happy new year! -- http://mail.python.org/mailman/listinfo/python-list
Re: module finalizer - is there such a beast?
You can execute cleanup code if the interpreter exits: http://docs.python.org/lib/module-atexit.html This will only cover the `Python's exit' part of your question, not the module reloading stuff. On the other hand, if you load a module you could set a global variable and check for it on reload... -- http://mail.python.org/mailman/listinfo/python-list
Embedding python code into text document question.
Dear all, I've written a program that parses a string or file for embedded python commands, executes them and fills in the returned value. The input might look like this: process id: $$return os.getpid()$$ current date: $$return time.ctime()$$ superuser: $$ if os.geteuid(): return Yes else: return No$$ I've tried several solutions using eval, execfile or compile, but none of those would solve my problem. Does anyone have a solution that works? Any suggestions? Any help will be appreciated :) Regards, Thomas. -- http://mail.python.org/mailman/listinfo/python-list
Re: Embedding python code into text document question.
Ok I've written a small example program to clarify matters: [SNIP] #!/usr/bin/python import os, sys, time def template(src, dst, sep): Copy file from src to dst, executing embedded python code. try: # read template file. f=open(src, rU) data=.join(f.readlines()) f.close() # find embedded python code and execute it. while True: # find embedded embedded python command. offset=data.find(sep) if offset 0: break offset2=data.find(sep, offset+1) if offset2 0: break cmd=data[offset+len(sep):offset2] # execute command. try: ret= exec(compile(cmd, 'from string', 'exec')) except: print error compiling code `%s'. % cmd # substitute command with return value. data=data[:offset]+str(ret)+\ data[offset2+len(sep):] # write translated input. f=open(dst, w) f.write(data) f.close() except: print error processing template file `%s'. % src # -- main --- if len(sys.argv) 2: template(sys.argv[1], sys.argv[2], '$$') [SNIP] This is the example input that works: [SNIP] process id: $$ret=os.getpid()$$ current date: $$ret=time.ctime()$$ superuser: $$ if os.geteuid(): ret=No else: ret=Yes$$ [SNIP] Now the `ret= ...' mechanism is not nice, I'd prefer to have a return statement instead. -- http://mail.python.org/mailman/listinfo/python-list
