On Sat, 26 Jan 2008 03:35:18 -0800, Oliver Beattie wrote:
> Just wondering if it is possible to pass a custom class instance
> instance to dict() by way of using methods like you can for iterators
> (__iter__, __getitem__ etc.) I see there is no __dict__ -- is there
> anything else I can use to achieve this?
Just write a method to return (key, value) pairs, and call that:
>>> class Parrot(object):
... def __init__(self):
... self.keys = [1, 2, 3, 4]
... self.values = ["one", "two", "three", "four"]
... def generate_tuples(self):
... for k,v in zip(self.keys, self.values):
... yield (k,v)
...
>>> p = Parrot()
>>> p.generate_tuples()
<generator object at 0xb7d1d78c>
>>> dict(p.generate_tuples())
{1: 'one', 2: 'two', 3: 'three', 4: 'four'}
Here's another way:
>>> class Foo(object):
... def __getitem__(self, i):
... if i > 4:
... raise IndexError
... return (i, 'foo %d' % i)
...
>>> dict(Foo())
{0: 'foo 0', 1: 'foo 1', 2: 'foo 2', 3: 'foo 3', 4: 'foo 4'}
Bonus marks if you can explain why they both work :)
(Hint: consider the "sequence protocol" and the "iterator protocol".)
--
Steven
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