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revive a generator

Steven D'Aprano steve+comp.lang.python at pearwood.info
Sat Oct 22 01:39:59 EDT 2011 
On Fri, 21 Oct 2011 16:25:47 -0400, Terry Reedy wrote:

> Here is a class that creates a re-iterable from any callable, such as a
> generator function, that returns an iterator when called, + captured
> arguments to be given to the function.
> 
> class reiterable():
>    def __init__(self, itercall, *args, **kwds):
>      self.f = itercall  # callable that returns an iterator
>      self.args = args
>      self.kwds = kwds
>    def __iter__(self):
>      return self.f(*self.args, **self.kwds)
> 
> def squares(n):
>      for i in range(n):
>          yield i*i
> 
> sq3 = reiterable(squares, 3)


We can do that even more simply, using a slightly different interface.

>>> from functools import partial
>>> sq3 = partial(squares, 3)

sq3 is now an iterator factory. You can't iterate over it directly, but 
it's easy to restart: just call it to return a fresh iterator.

>>> list(sq3())
[0, 1, 4]
>>> list(sq3())
[0, 1, 4]


-- 
Steven
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