Are .pyc files portable?

[Lie Ryan]

On Fri, 07 Nov 2008 18:36:41 -0800, Roy Smith wrote:

> I'm using Python as part of a test fixture for a large (mostly C++)
> software project.  We build on a lot of different platforms, but Solaris
> is a special case -- we build on Solaris 8, and then run our test suite
> on Solaris 8, 9, and 10.  The way the build system is set up (driven by
> Build Forge), the Sol 8, 9, and 10 test passes can happen in any order. 
> The tests all run in a common directory, shared by NFS on all three
> machines.
> 
> If (for example) the Sol 10 tests run first, and create .pyc files, will
> those .pyc files work correctly when the Sol 8 and Sol 9 test passes
> come along and run them in the same directories?
> 
> The python binary is a build of 2.5.1 that we did on Solaris 8.  The
> same binary is used on all Solaris platforms.  Although we do separate
> 32-bit and 64-bit builds of our product, the python binary we use for
> the test driver is the same 32-bit build on all of them.
> 
> A related question: is there any way to tell Python to put the .pyc
> files in some other directory, i.e. NOT the same directory where the .py
> sources are.  That would make things cleaner, since we could just tell
> each system to put its .pyc's in a different place.
> 
> We've also got some games we play with symlink farms (lndir), which may
> be part of the solution here, but I want to explore all the
> possibilities first.

If all that responses confuse you, the simple answer is:
1. Python bytecode is cross-platform 
2. but is not cross-version

i.e. as long as the .pyc can be run accross different platforms as long 
as the version number of the compiling python and executing python is 
equal.

A simple solution if you've got different version of python across many 
platform is to provide a .py file that redirects the program to each 
version-specific .pyc (cross-platform and cross-version if written with 
some care)