[Distutils] desirability of multiple, divergent Python instances

[Stephen Waterbury]

Ben Finney wrote:
> Greg Ewing <greg.ewing at canterbury.ac.nz> writes:
> 
>> Gael Varoquaux wrote:
>>> a second Python needs to be installed on top of the system Python
>>> to add modules to it.
>> Maybe the system should come with two pythons installed, one for use
>> by the system and the other for users to add things to. Or at least
>> be set up so that it appears that way -- they might share files
>> under the hood.
> 
> I can't see how this is a good idea. I've seen it mentioned multiple
> times in this thread, but without justification.
> 
> It's my position that the Python instance one uses for development
> should diverge as little as possible from the default system instance.
> Otherwise one is actively pursuing a recipe for dependency failures
> when one eventually deploys the result.

> Yes, there should be a way to deploy the code one is actively
> developing and testing to some location that will not affect the rest
> of the operation of the system. That is a far cry from asking that
> there should be multiple, divergent Python instances on the system.
> 
> The further step of saying that the operating system should not use
> the same Python instance as a "user" on the system (and note that the
> line between those is far from clear), but instead should use some
> Python instance that behaves differently from every other use of
> Python on the system, seems like an even worse proposition, for the
> above reasons.
> 
> Help me understand, please.

Have you read my proposal?  It's in the message posted by me to this
thread at 12:31 PM today.

My main motivation in proposing it is to give the user complete control
over the Python environment that is in their path -- which is not easy to
do on Debian/Ubuntu at the moment -- by giving the Python utilities and
packages that OS-related functions depend on a completely insular Python
environment that the OS can manage however it sees fit.  In my view, both
as a developer and a user, but especially as a developer, it would make
life easier.

Steve