[Python-Dev] PEP 342: simple example, closure alternative
alain.poirier at net-ng.com
Fri Aug 26 18:21:58 CEST 2005
Le Vendredi 26 Août 2005 16:57, Guido van Rossum a écrit :
> On 8/25/05, Ian Bicking <ianb at colorstudy.com> wrote:
> > More generally, I've been doing some language comparisons, and I don't
> > like literal but non-idiomatic translations of programming patterns.
> True. (But that doesn't mean I think using generators for this example
> is great either.)
> > So I'm considering better ways to translate some of the same use cases.
> Remember that this particuar example was invented to show the
> superiority of Lisp; it has no practical value when taken literally.
> If you substitute a method call for the "acc += incr" operation, the
> Python translation using nested functions is very natural. For larger
> examples, I'd recommend defining a class as always.
For example, I often use this class to help me in functional programming :
_marker = ()
def __init__(self, v=None):
self.v = v
def __call__(self, v=_marker):
if v is not _marker:
self.v = v
and so the nested functions become very functional :
acc = var(n)
return lambda incr: acc(acc()+incr)
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