[Python-Dev] multi-version parallel-installed modules

[M.-A. Lemburg]

Michael Foord wrote:
> On 18/08/2010 15:34, Neal Becker wrote:
>> Is there any proposal to accommodate having parallel-installed multiple
>> versions of modules?

You can easily implement such a setup by placing the module versions
into a separate dir and then adding the right version dir to you
sys.path before test startup.

E.g.

export PYTHONPATH=mymodule/3.0; python test.py
export PYTHONPATH=mymodule/3.1; python test.py

>> I have client code in multiple projects using version x.y of a C-compiled
>> module A.
>>
>> I want to test a new version x.z of module A, but all client software
>> needs
>> to be recompiled against the new version.  If I just install the
>> module, all
>> the other client software breaks.
>>
>> I know I could test using virtualenv, but there would be a lot of
>> modules to
>> install into virtualenv to run the tests, so this would be
>> cumbersome.  I'd
>> prefer to have multiple version co-exist so I could update projects to
>> the
>> new version at my convenience.
>>
>> How does this situation happen?  I have lots of c++ code using pyublas,
>> which allows c++ code written to the boost::ublas interface to operate on
>> numpy vectors/matrixes.  pyublas is built against boost libs. pyublas
>> installs a module, whose purpose is to register conversions.
>>
>> When I update boost libs, I have to rebuild pyublas and install the
>> updated
>> module.  Then rebuild my client software modules.  If pyublas is built
>> against a different boost version than my client modules, the conversions
>> will fail.

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