MethodChain

Paul McGuire ptmcg at austin.rr.com
Sun Jul 20 07:42:04 CEST 2008


On Jul 20, 12:01 am, Marc 'BlackJack' Rintsch <bj_... at gmx.net> wrote:
> The methods are a problem IMHO.  You can't add an own method/function with
> the name `fire()` or `toFunction()`.  `MethodChain` has to know all
> functions/methods in advance.  You can add the methods of whole classes at
> once and there are over 300 pre-added, this begs for name clashes.
>
> Ciao,
>         Marc 'BlackJack' Rintsch

If you shift the syntax just a bit, instead of writing a.b.c, pass a,
b, and c as the args to a MethodChain object.  Here's a rough stab at
the problem:

class MethodChain(object):
    def __init__(self, *fns):
        self.fns = fns[:]
    def __call__(self,*args):
        if self.fns:
            for f in self.fns:
                args = (f(*args),)
        return args[0]

def dncase(s):
    return s.lower()

def upcase(s):
    return s.upper()

def stripVowels(s):
    return "".join( c for c in s if c not in "aeiou" )

def selectItems(items,s):
    return "".join(c for i,c in enumerate(s) if i in items)

from functools import partial

chn = MethodChain(
        dncase,
        stripVowels,
        upcase,
        partial(selectItems,(0,2))
        )

print chn("FoO Bar")


-- Paul



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