[Python-Dev] Breaking undocumented API

R. David Murray rdmurray at bitdance.com
Wed Nov 10 16:48:37 CET 2010

On Wed, 10 Nov 2010 13:12:09 +0900, "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 think Tres was referring to certain packages (which shall remain
nameless since I don't feel like googling to find one) whose
documentation recommends the 'from <me> import *' methodology.

At least that's how I read "Module writers who..."  (that is, he's not
saying the *module* expects to be imported that way). [*]

R. David Murray                                      www.bitdance.com

[*] although reading that sentence literally, the thought of such a
module writer themselves being imported that way (a la Tron) has a
certain charm....

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