When implementing the rich comparison operators for some sort of
container, it's tempting to save code by doing something like:
class LarchTree:
...
def __gt__(self, other):
# A lot of code to traverse the tree
def __le__(self):
return not self > other
However, if I'm thinking correctly, this is a bad idea. The
reasoning being that > and <= are not required to be each others
opposite for arbitrary value types, and may not even both be
supplied by the contained objects.
If a LarchTree user stores objects that don't support __gt__,
will he have a legitimate complaint when using LarchTree.__le__
results in an attribute error?
--
Neil Cerutti
--
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