module not callable - why not?

[Bengt Richter]

On Tue, 20 Apr 2004 12:42:44 GMT, Michael Hudson <mwh at python.net> wrote:

>Paul Rubin <http://phr.cx@NOSPAM.invalid> writes:
>
>> And yet, you can call a class instance if it has a __call__
>> operation defined.  I don't see why modules shouldn't be the same.
>
>Well, for a possible counter argument, consider that you can only call
>an instance of a new-style class if the CLASS defines the __call__
>method...
>
ISTM you could give the module class a __call__ property, so you could
customize the callability of module instances something like:

 >>> print '----\n%s----'% file('callablinst.py').read()
 ----
 class Callablinst(object):
     def _getcallable(self): return self.__dict__['__call__']
     def _setcallable(self,v): self.__dict__['__call__'] = v
     __call__ = property(_getcallable, _setcallable)
 ----
 >>> from callablinst import Callablinst as CI
 >>> c = CI()
 >>> c()
 Traceback (most recent call last):
   File "<stdin>", line 1, in ?
   File "callablinst.py", line 2, in _getcallable
     def _getcallable(self): return self.__dict__['__call__']
 KeyError: '__call__'
 >>> c.__call__ = lambda:'I am callable now ;-)'
 >>> c()
 'I am callable now ;-)'
 >>> c2 = CI()
 >>> c2()
 Traceback (most recent call last):
   File "<stdin>", line 1, in ?
   File "callablinst.py", line 2, in _getcallable
     def _getcallable(self): return self.__dict__['__call__']
 KeyError: '__call__'
 >>> c2.__call__ = lambda:'I am c2'
 >>> c2()
 'I am c2'

UIAM, a def __call__(whatever): ... somewhere in the global scope of such a
module's source should then be picked up (depending on how the execution of
the def actually does the function name binding perhaps -- presumably it would
either bypass the attribute/property mechanism, or would use it). Either way
I would guess subsequent use of the module as callable would pick up the function
bound to __call__, but I'm not certain.

Regards,
Bengt Richter