Stupid ways to spell simple code

Steven D'Aprano steve+comp.lang.python at pearwood.info
Tue Jul 2 00:09:18 CEST 2013


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



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