Platform independent code?

[saneman]

I have read that Python is a platform independent language. But on this
page:

http://docs.python.org/tut/node4.htm...00000000000000

it seems that making a python script executable is platform dependant:

2.2.2 Executable Python Scripts
On BSD'ish Unix systems, Python scripts can be made directly executable,
like shell scripts, by putting the line
#! /usr/bin/env python
(assuming that the interpreter is on the user's PATH) at the beginning of
the script and giving the file an executable mode. The "#!" must be the
first two characters of the file. On some platforms, this first line must
end with a Unix-style line ending ("\n"), not a Mac OS ("\r") or Windows
("\r\n") line ending. Note that the hash, or pound, character, "#", is used
to start a comment in Python.

The script can be given an executable mode, or permission, using the chmod
command:
$ chmod +x myscript.py

Are there any guidelines (API'S) that gurantees that the python code will be
platform independent?

[Matthieu Brucher]

Hi,

Python is a platform independent language, period. You can always
excute a Python script with python script.py. Now, with Windows, you
can execute the script by doucle-clicking on it. With Linux, it's
different, you have to use the shebang line to execute a script with
the correct interpreter. But this has nothing to do with the fact that
Python is a platform independent language.
Some modules may not be available on all platform, for the answer to
this question, see the documentation of the module ;)

Matthieu

2008/6/14 saneman <as*@ad.com>:

I have read that Python is a platform independent language. But on this
page:

http://docs.python.org/tut/node4.htm...00000000000000

it seems that making a python script executable is platform dependant:

2.2.2 Executable Python Scripts
On BSD'ish Unix systems, Python scripts can be made directly executable,
like shell scripts, by putting the line
#! /usr/bin/env python
(assuming that the interpreter is on the user's PATH) at the beginning of
the script and giving the file an executable mode. The "#!" must be the
first two characters of the file. On some platforms, this first line must
end with a Unix-style line ending ("\n"), not a Mac OS ("\r") or Windows
("\r\n") line ending. Note that the hash, or pound, character, "#", is used
to start a comment in Python.

The script can be given an executable mode, or permission, using the chmod
command:
$ chmod +x myscript.py

Are there any guidelines (API'S) that gurantees that the python code will be
platform independent?
--
http://mail.python.org/mailman/listinfo/python-list

--
French PhD student
Website : http://matthieu-brucher.developpez.com/
Blogs : http://matt.eifelle.com and http://blog.developpez.com/?blog=92
LinkedIn : http://www.linkedin.com/in/matthieubrucher

[Larry Bates]

saneman wrote:

I have read that Python is a platform independent language. But on this
page:

http://docs.python.org/tut/node4.htm...00000000000000

it seems that making a python script executable is platform dependant:

2.2.2 Executable Python Scripts
On BSD'ish Unix systems, Python scripts can be made directly executable,
like shell scripts, by putting the line
#! /usr/bin/env python
(assuming that the interpreter is on the user's PATH) at the beginning of
the script and giving the file an executable mode. The "#!" must be the
first two characters of the file. On some platforms, this first line must
end with a Unix-style line ending ("\n"), not a Mac OS ("\r") or Windows
("\r\n") line ending. Note that the hash, or pound, character, "#", is used
to start a comment in Python.

The script can be given an executable mode, or permission, using the chmod
command:
$ chmod +x myscript.py

Are there any guidelines (API'S) that gurantees that the python code will be
platform independent?

Generally you have to stay away from platform "dependent" constructs. Esamples:

1) Use os.path methods everywhere in your code so you won't need to worry about
os.path.sep (slash or backslash).

2) Use lowest common denominator when naming files to make your scripts work
cross platform.

3) Stay away from os-specific calls/interfaces when possible. Manipulating file
permissions, etc is always os-specific.

4) Use config files instead of relying on registry in Windows.

5) Stay away from code that depends on 32/64 bit objects or endian-ness of
storage (struct objects). This is machine specific not OS specific but still
counts.

6) If you have GUI, use something like wxWindows which provides cross platform
GUI support.

7) Be careful using non-Python libraries (C-libraries) should be done with care
to make sure that the library is available for all target operating systems.

8) using os.system or the subsystem module must be done with much care and
probably won't be cross platform compatible.

Hope the suggestions help.

-Larry

[bukzor]

On Jun 14, 6:28*am, "saneman" <[e-mail]:

I have read that Python is a platform independent language. *But on this
page:

http://docs.python.org/tut/node4.htm...00000000000000

it seems that making a python script executable is platform dependant:

2.2.2 Executable Python Scripts
On BSD'ish Unix systems, Python scripts can be made directly executable,
like shell scripts, by putting the line

#! /usr/bin/env python
(assuming that the interpreter is on the user's PATH) at the beginning of
the script and giving the file an executable mode. The "#!" must be the
first two characters of the file. On some platforms, this first line must
end with a Unix-style line ending ("\n"), not a Mac OS ("\r") or Windows
("\r\n") line ending. Note that the hash, or pound, character, "#", is used
to start a comment in Python.

The script can be given an executable mode, or permission, using the chmod
command:

$ chmod +x myscript.py

Are there any guidelines (API'S) that gurantees that the python code will be
platform independent?

The only guarantee is testing it on both yourself. Some modules are
inherently os-dependant (much of the 'os' module for example), and
some constructs just don't work on all platforms (using
os.environ['LOGNAME'] or system('cat file') as examples).

If you stick to python code that doesn't touch the OS directly, you
won't (read: shouldn't) have a problem, but when you start interacting
with the OS directly you have to think hard about what you're doing.

--Buck