Stupid ways to spell simple code
88888 Dihedral
dihedral88888 at gmail.com
Tue Jul 2 00:16:39 EDT 2013
Steven D'Aprano於 2013年7月2日星期二UTC+8上午6時09分18秒寫道:
> On Mon, 01 Jul 2013 20:36:29 +0100, Marcin Szamotulski wrote:
>
>
>
> > Here is another example which I came across when playing with
>
> > generators, the first function is actually quite useful, the second
>
> > generator is the whole fun:
>
> >
>
> > from functools import wraps
>
> > def init(func):
>
> > """decorator which initialises the generator """
>
> > @wraps(func)
>
> > def inner(*args, **kwargs):
>
> > g = func(*args, **kwargs)
>
> > g.send(None)
>
> > return g
>
> > return inner
>
> >
>
> > @init
>
> > def gen(func):
>
> > x = (yield)
>
> > while True:
>
> > x = (yield func(x))
>
> >
>
> >
>
> > now if you have function f
>
> > def f(arg):
>
> > return arg**2
>
> >
>
> > then calling f(5) is the same as
>
> >
>
> > g = gen(f)
>
> > g.send(5)
>
>
>
>
>
>
>
> I think you must be missing an important part of the trick, because
>
> calling f(5) returns 25. It's not:
>
>
>
> @gen
>
> def f(arg):
>
> return arg**2
>
>
>
>
>
> because that raises TypeError.
>
>
>
>
>
>
>
>
>
> --
>
> Steven
Lets be serious about generators and iterators.
A generator can be used only once in a program
is different from a a generator method of a class that
can produce several instances with generators of the same kind
but operated in each instance of the class.
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