Terry Reedy wrote:
Rasmus Fogh wrote:
much, though, just to get code like this to work as intended:
alist.append(x)
print ('x is present: ', x in alist)
Even if rich comparisons as you propose, the above would *still* not
necessarily work. Collection classes can define a __contains__ that
overrides the default and that can do anything, though True/False is
recommended.
No, it's actually required.
In [4]: class A(object):
def __contains__(self, other):
return 'foo'
...:
...:
In [7]: a = A()
In [8]: 1 in a
Out[8]: True
Okay, so it will coerce to True/False for you, but unlike rich comparisons, the
return value must be interpretable as a boolean.
--
Robert Kern
"I have come to believe that the whole world is an enigma, a harmless enigma
that is made terrible by our own mad attempt to interpret it as though it had
an underlying truth."
-- Umberto Eco
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