[Python-Dev] Some new additions to functools

[Paul Hankin]

On 4/15/07, SevenInchBread <adamadamadamamiadam at gmail.com> wrote:
> So I've cooked up some very simple functions to add to functools - to expand
> it into a more general-purpose module.
>
> def cat(x): return x
>
> class nullfunc(object):
>     def __call__(self, *args, **kargs): return self
>     def __getattr__(self, name):        return getattr(None, name)
>
> def multimap(func, seq, n=2):
>     assert n > 0, "n must be positive"
>     if n == 1: return map(func, seq)
>     else:       return map(lambda x: multimap(func, x, n-1), seq)
>
> def multifilter(func, seq, n=2):
>     return multimap(lambda x: filter(func, x), seq, n-1)
>
> def multireduce(func, seq, n=2):
>     return multimap(lambda x: reduce(func, x), seq, n-1)

-0 for cat (renamed to 'identity'), -1 for the rest.

I've occasionally wanted multimap but only in the default
case where it is simpler to be explicit.

-- 
Paul Hankin