iu2 wrote:
> I'm trying to convert functions - pass a few functions to a converting
> function, which change their behaviour and return the changed
> functions:
>
> >>> def cfuncs(*funcs):
> n = []
> for f in funcs:
> def ff(*args, **key):
> print 'Start!', f.func_name
> res = f(*args, **key)
> print 'End', f.func_name
> return res
> n.append(ff)
> return n
>
> then I try it using two functions:
>
> >>> def f1():
> print 'hello'
>
>
> >>> def f2(x):
> return 2 * x
>
> Eventually:
> >>> newfuncs = cfuncs(f1, f2)
>
> I would expect newfuncs to hold changed versions of f1 and f2, but
> what is actually contained in newfuncs is twice the changed version of
> f2.
That is because the inner ff() references f which is a local variable of
cfuncs(). By the time you invoke your newly created functions cfuncs() and
thus the 'for f in funcs' loop has finished and the value of f is that of
the last item in the funcs tuple. You can avoid the problem with another
indirection
def make_ff(f):
def ff(*args, **key):
print 'Start!', f.func_name
res = f(*args, **key)
print 'End', f.func_name
return res
return ff
def cfuncs(*funcs):
return [make_ff(f) for f in funcs]
Peter
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