Overriding member methods in __init__

[Arnaud Delobelle]

On Dec 3, 3:36 pm, Hrvoje Niksic <hnik... at xemacs.org> wrote:
> Allowing instance lookup of __call__ would slow down normal uses of
> the internal __call__ mechanism.  Since it used for all function and
> method calls, it needs to remain extremely fast.  If you're really
> worried about performance, you can define YesNo.__new__ to return
> either a Yes instance or a No instance, depending on the value:
>
> class YesNo(object):
>     def __new__(cls, which):
>         if which:
>             return object.__new__(Yes)
>         else:
>             return object.__new__(No)
>
>     def yes(self, val):
>         print 'Yes', val
>
>     def no(self, val):
>         print 'No', val
>
> class Yes(YesNo):
>     def __call__(self, val):
>         self.yes(val)          # no check at every call
>
> class No(YesNo):
>     def __call__(self, val):
>         self.no(val)           # likewise
>

Why not simply do:

class YesNo(object):
    def __init__(self, which):
        self.yesno = which and self.yes or self.no
    def yes(self, val):
        print 'Yes', val
    def no(self, val):
        print 'No', val
    def __call__(self, val):
        self.yesno(val)

I don't know which is fastest but I don't think there would be much
difference.

--
Arnaud