Help with generators outside of loops.

Steven Bethard steven.bethard at gmail.com
Wed Dec 8 18:04:38 CET 2004


Christopher J. Bottaro wrote:
> Wow, good advice.  One question, how is the generator class implemented so
> that if assigned to a tuple/list, it knows what to do?  Is it possible to
> overload the assignment operator kinda like in C++?

Tuple unpacking works with generators because generators implement the 
iterator protocol.  Any object that implements the iterator protocol can 
be used in tuple unpacking:

 >>> class I(object):
...     def __init__(self, n):
...         self.n = n
...         self.i = -1
...     def next(self):
...         self.i += 1
...         if self.i == self.n:
...             raise StopIteration
...         return self.i
...     def __iter__(self):
...         return self
...
 >>> x, y, z = I(3)
 >>> x, y, z
(0, 1, 2)

So you're not really overloading the assignment operator; you're taking 
advantage of something the assignment operator already does.

Steve



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