[Distutils] shebang line modified by setuptools

[Dave Peterson]

Gael Varoquaux wrote:
> On Mon, Apr 14, 2008 at 01:30:14PM +1200, Greg Ewing wrote:
>   
>> 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 am quite wary about these proposals, as well as the one environment per
> application ones.
>   

In my experience, it is a fairly standard practice across all platforms 
to install independent application environments for any large, complex 
applications that come with a vendor support agreement.   Admittedly, 
that isn't alot of Python applications, especially of the kind you're 
referring to where users are expected to add, remove, and intermix 
modules.  However, that doesn't mean there aren't any Python apps that 
do fit the bill -- in fact, Enthought does alot of that.   We want our 
apps to work even if the sysadmin upgrades the system libraries, Python, 
or what have you, or if the user installs multiple applications that 
have competing library requirements.

> What you propose resembles very much to what MacOSX does, and MacOSX
> seems just so broken for Python. I don't use it, but I see on the
> different scientific-Python-related mailing lists how users have
> difficulties with MacOSX, and I have heard many people complain about
> this "feature".
>
> As a per-application environment, I think it is bad, because it limits
> reuse. As I see things, applications should be able to have access to all
> the Python modules installed, to be able to use them, if they need. I get
> definitely see applications having more feature if some modules are
> installed (eg. Sphinx, which does syntax highlighting if pygments is
> installed).
>
> I think this discussion is really going on because Python does not have
> good library-versioning support. What it needs is to get this, and not to
> get complete isolation, apart for some system-critical tasks, and only
> for these. AFAIK this is one of the problems setuptools is trying to
> solve. Not everybody is happy with the technical solution setuptools has
> come up, this only means it has to be improved.
>   

IMO, this sort of multi-version thing only works if *everything* in the 
stack participates fully.  I think the reason more things don't do this 
is because of the maintenance load it puts on developers / release 
managers to bump and synchronize versions apporpriately.


-- Dave

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