[Python-Dev] issue5578 - explanation

[Chris Withers]

R. David Murray wrote:
> On Wed, 1 Apr 2009 at 13:12, Chris Withers wrote:
>> Guido van Rossum wrote:
>>>  Well hold on for a minute, I remember we used to have an exec
>>>  statement in a class body in the standard library, to define some file
>>>  methods in socket.py IIRC. 
>>
>> But why an exec?! Surely there must be some other way to do this than 
>> an exec?
> 
> Maybe, but this sure is gnarly code:
> 
>     _s = ("def %s(self, *args): return self._sock.%s(*args)\n\n"
>           "%s.__doc__ = _realsocket.%s.__doc__\n")
>     for _m in _socketmethods:
>         exec _s % (_m, _m, _m, _m)
>     del _m, _s

I played around with this and managed to rewrite it as:

from functools import partial
from new import instancemethod

def meth(name,self,*args):
     return getattr(self._sock,name)(*args)

for _m in _socketmethods:
     p = partial(meth,_m)
     p.__name__ = _m
     p.__doc__ = getattr(_realsocket,_m).__doc__
     m = instancemethod(p,None,_socketobject)
     setattr(_socketobject,_m,m)

Have I missed something or is that a suitable replacement that gets rid 
of the exec nastiness?

Chris

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