I have a class that only contains attributes and I would like packing/unpacking to work on it. What collections.abc
should I implement to get this behaviour?
class Item(object): def __init__(self, name, age, gender) self.name = name self.age = age self.gender = gender a, b, c = Item("Henry", 90, "male")
I would like to avoid using a namedtuple
.
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Answer
You can unpack any Iterable
. This means you need to implement the __iter__
method, and return an iterator. In your case, this could simply be:
def __iter__(self): return iter((self.name, self.age, self.gender))
Alternatively you could make your class an Iterator
, then __iter__
would return self
and you’d need to implement __next__
; this is more work, and probably not worth the effort.
For more information see What exactly are Python’s iterator, iterable, and iteration protocols?
Per the question I linked above, you could also implement an iterable with __getitem__
:
def __getitem__(self, index): return (self.name, self.age, self.gender)[index]