invoke method on many instances

[Gabriel Genellina]

En Sat, 18 Jul 2009 12:31:46 -0300, Alan G Isaac <alan.isaac at gmail.com>  
escribió:

>> On Fri, 17 Jul 2009 05:19:50 +0000, Alan G Isaac wrote:
>>> def apply2(itr, methodname, *args, **kwargs):
>>>     f = operator.methodcaller(methodname, *args, **kwargs)
>>>     for item in itr:
>>>         f(item)
>
>
> On 7/17/2009 3:45 AM Steven D'Aprano apparently wrote:
>> for obj in objects:
>>     getattr(obj, methodname)(*args, **kwargs)
>
>
> Are there any obvious considerations in choosing
> between those two?

The operator.methodcaller version is faster in my tests for large  
collections, but slightly slower when you have very few elements.

<code>
import operator
import timeit

class X:
   def method(self, x, y, **kw): pass

def apply1(itr, methodname, *args, **kwargs):
     for item in itr:
         getattr(item, methodname)(*args, **kwargs)

def apply2(itr, methodname, *args, **kwargs):
     f = operator.methodcaller(methodname, *args, **kwargs)
     for item in itr:
         f(item)

L=[X() for _ in range(3000)]
apply1(L,'method', 1, 2, foo=3)
apply2(L,'method', 1, 2, foo=3)

timeit.timeit(setup="from __main__ import apply1,apply2,L",  
stmt="apply1(L,'method', 1, 2, foo=3)", number=1000)
timeit.timeit(setup="from __main__ import apply1,apply2,L",  
stmt="apply2(L,'method', 1, 2, foo=3)", number=1000)
</code>

-- 
Gabriel Genellina