[Python-Dev] Breaking undocumented API

[Floris Bruynooghe]

On 10 November 2010 04:12, Stephen J. Turnbull <stephen at xemacs.org> wrote:
> Nick Coghlan writes:
>
>  > > Module writers who compound the error by expecting to be imported
>  > > this way, thereby bogarting the global namespace for their own
>  > > purposes, should be fish-slapped. ;)
>  >
>  > Be prepared to fish-slap all of python-dev then - we use precisely
>  > this technique to support optional acceleration modules. The pure
>  > Python versions of pairs like profile/_profile and heapq/_heapq
>  > include a try/except block at the end that does the equivalent of:
>  >
>  >   try:
>  >     from _accelerated import * # Allow accelerated overrides
>  >   except ImportError:
>  >     pass # Use pure Python versions
>
> But these identifiers will appear at the module level, not global, no?
> Otherwise this technique couldn't be used.  I don't really understand
> what Tres is talking about when he writes "modules that expect to be
> imported this way".  The *imported* module shouldn't care, no?  This
> is an issue for the *importing* code to deal with.

I can't think of stdlib examples, but for 3rd party packages I'd say
storm.locals and fabric.api are examples of packages designed with
"from foo import * " in mind.  So this does happen.

Regards
Floris

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