[Python-Dev] Letting ../site-packages override the standard lib ?!

M.-A. Lemburg mal@lemburg.com
Fri, 08 Sep 2000 23:31:06 +0200

Jeremy Hylton wrote:
> >>>>> "MAL" == M -A Lemburg <mal@lemburg.com> writes:
>   MAL> To provide more flexibility to the third-party tools in such a
>   MAL> situation, I think it would be worthwhile moving the
>   MAL> site-packages/ entry in sys.path in front of the lib/python2.0/
>   MAL> entry.
>   MAL> That way a third party tool can override the standard lib's
>   MAL> package or module or take appropriate action to reintegrate the
>   MAL> standard lib's package namespace into an extended one.
>   MAL> What do you think ?
> I think it is a bad idea to encourage third party tools to override
> the standard library.  We call it the standard library for a reason!
> It invites confusion and headaches to read a bit of code that says
> "import pickle" and have its meaning depend on what oddball packages
> someone has installed on the system.  Good bye, portability!

Ok... so we'll need a more flexible solution.
> If you want to use a third-party package that provides the same
> interface as a standard library, it seems much clearn to say so
> explicitly.
> I would agree that there is an interesting design problem here.  I
> think the problem is support interfaces, where an interface allows me
> to write code that can run with any implementation of that interface.
> I don't think hacking sys.path is a good solution.

No, the problem is different: there is currently on way to
automatically add subpackages to an existing package which is
not aware of these new subpackages, i.e. say you have a
package xml in the standard lib and somebody wants to install
a new subpackage wml.

The only way to do this is by putting it into the xml
package directory (bad!) or by telling the user to

	import xml_wml

first which then does the

	import xml, wml
	xml.wml = wml

to complete the installation... there has to be a more elegant

Marc-Andre Lemburg
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