On 22:09 Mon 01 Jul , Steven D'Aprano wrote:
> 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
> --
> http://mail.python.org/mailman/listinfo/python-list
Sure it does, you're now supposed to use .send method instead of
calling it but this is just different syntax. If you want to call it
use this :
def identity(func):
@init
def gen(func):
x = (yield)
while True:
x = (yield func(x))
return gen(func).send
Now you will get:
>>> @identity
>>> def f(a): a+1
...
>>> f(0)
1
Best regards,
Marcin
--
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