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From: Joshua Landau <joshua@landau.ws>
Date: Fri, 12 Jul 2013 08:09:57 +0100
Subject: Re: Documenting builtin methods
To: alex23 <wuwei23@gmail.com>
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On 12 July 2013 04:43, alex23 <wuwei23@gmail.com> wrote:
>
> My last post seems to have been eaten by either Thunderbird or the
> EternalSeptember servers, but it contained an erroneous claim that the
> straight function version performed as well as the factory one. However, in
> the interim a co-worker has come up with a slightly faster variant:
>
> from functools import partial
> from collections import deque
>
> class exhaust_it(partial):
>     """custom doc string"""
>
> exhaust_it = exhaust_it(deque(maxlen=0).extend)
>
> Shadowing the class name with the partial instance will ensure it has the
> same name when accessed via help(), and it's a simple way to avoid needing
> to clean up the namespace, as well.

That's beautiful. You could even trivially make a wrapper function:

def wrap_docstring(function, docstring, *, name=None):
    class Wrapper(partial): pass
    Wrapper.__name__ = function.__name__ if name is None else name
    Wrapper.__doc__ = docstring
    return Wrapper(function)

which is no slower. You get great introspection through the "func"
attribute, too :).

Also:

>>> times = time_raw(), time_function(), time_factory(), time_argument_hack(), time_partial()
>>> [round(time/times[0], 1) for time in times]
[1.0, 16.8, 3.1, 3.0, 1.8]

This times almost purely the constant overhead by calling
exhaust_iterabe on an empty iterable. So your friend wins the
premature optimisation test, too.