[Python-ideas] pythonv / Python path

[Ian Bicking]

On Sat, Oct 23, 2010 at 5:11 PM, Brett Cannon <brett at python.org> wrote:

> On Sat, Oct 23, 2010 at 14:33, Ian Bicking <ianb at colorstudy.com> wrote:
> > On Sat, Oct 23, 2010 at 4:27 PM, Brett Cannon <brett at python.org> wrote:
> >>
> >> Is this email meant to simply point out the existence of pythonv, or
> >> to start a conversation about whether something should be tweaked in
> >> Python so as to make pythonv/virtualenv easier to implement/use?
> >
> > Both?  I have felt guilty for not following up on what Larry did, so this
> is
> > my other-people-should-think-about-this-too email.
> >
> >>
> >> If it's the latter then let's have the conversation! This was brought
> >> up at the PyCon US 2010 language summit and the consensus was that
> >> modifying Python to make something like virtualenv or pythonv easier
> >> to implement is completely acceptable and something worth doing.
> >
> > OK, sure!  Mostly it's about changing site.py.
>
> OK, what exactly needs to change?
>

Well, add a notion of "prefixes", where the system sys.prefix is one item,
but the environment location is the "active" sys.prefix.  Then most of the
site.py changes can follow logically from that (whatever you do for the one
prefix, do for all prefixes).  Then there's a matter of using an
environmental variable to add a new prefix (or multiple prefixes --
inheritable virtualenvs, if virtualenv allowed such a thing).  In the
pythonv implementation it sets that variable, and site.py deletes that
variable (it could be a command-line switch, that's just slightly hard to
implement -- but it's not intended as an inheritable attribute of the
execution environment like PYTHONPATH).

>  The pythonv executable is
> > itself very simple, just a shim to make #! easier.
>
> But that's in C, though, right? What exactly does it do? It would be
> best to make it if the shim can be in Python so that other VMs can
> work with it.
>

#! doesn't work with a Python target, otherwise it would be easy to
implement in Python.  #! is awful.

-- 
Ian Bicking  |  http://blog.ianbicking.org
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