2 different versions of python compiling files.

[Hans Nowak]

TkNeo wrote:
> I am trying to upgrade from python 2.3 to 2.4 but not all machines can
> be upgraded. Can you guys tell me if this scenario is possible.
> 
> 1. Any machine that uses .py files that use libraries that require 2.4
> will have 2.4 on it.
> 2. rest of the machines will have 2.3
> 
> now there is a shared drive. lets say i write a new library called
> testlib.py and put it on the shared drive .. when a script uses it
> from a 2.4 based machine, it will generate a testlib.pyc and leave it
> on the shared drive. going forward that .pyc is used until the
> original lib is changed. now lets say a 2.3 based machine is trying to
> use that lib. it will try to use that pyc file which was compiled by
> py2.4. will it work or crash ?

It should work, as long as the original .py file is still there.  Each Python 
version will check for a .pyc file *corresponding to that version* (e.g. Python 
2.4 will look for a .pyc file compiled with 2.4), and create one if it doesn't 
exist, overwriting any existing .pyc file in the process.

If the original .py file is *not* there, it will most likely not work.  If you 
try to import a .pyc file with the wrong version number, you get something like 
this:

 >>> import foo
Traceback (most recent call last):
   File "<stdin>", line 1, in ?
ImportError: Bad magic number in foo.pyc

I'm not sure what would happen if multiple Pythons try to write a .pyc file at 
the same time, though...

-- 
Hans Nowak (zephyrfalcon at gmail dot org)
http://4.flowsnake.org/