I'm trying to understand custom iterators in Python, and created the
following toy class for sequence comparison, which seems to work:
class Foo(object):
"""A toy class to experiment with __eq__ and __iter__"""
def __init__(self, listA, listB):
self.head, self.tail = listA, listB
def __iter__(self):
return iter(self.head[:]+self.tail[:])
def __eq__(self, other):
"""Foo instances are equal if their respective subsequences,
head, tail, are in the same order"""
diff = [i for i, j in zip(self, other) if i != j]
return len(diff) == 0
>>> f1 = Foo( [1,2], ['a','b','c'] )
>>> f2 = Foo( [1,2], ['a','b','c'] )
>>> f3 = Foo( [1,2], ['a','b','d'] )
>>> f1 == f2, f1 == f3
(True, False)
I'm not really sure if I'm implementing iter() correctly, for
instance: should I make copies of the sublists? Should I try to
implement my own next() method?
Advice, comments, and links to good tutorial web pages on iterators
are appreciated!
Thanks,
Marcus
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