[Python-Dev] Breaking undocumented API

[Michael Foord]

On 10/11/2010 15:48, R. David Murray wrote:
> 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.

Contenders include popular libraries like fabric and django:

http://docs.fabfile.org/0.9.2/usage/fabfiles.html
http://docs.djangoproject.com/en/1.2/intro/tutorial03/

All the best,

Michael

> 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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