How is True < 2 implemented?

Question

It's not implemented directly on bool.

>>> True.__lt__(2)
AttributeError: 'bool' object has no attribute '__lt__'

And it's apparently not implemented on int either:

>>> super(bool, True).__lt__(2)
AttributeError: 'super' object has no attribute '__lt__'

There is no reflected version of __lt__ for 2 to control the operation, and since int type is not a subclass of bool that would never work anyway.

Python 3 behaves as expected:

>>> True.__lt__(2)
True

So, how is True < 2 implemented in Python 2?

Answer 1

You didn't find super(bool, True).__lt__ because int uses the legacy __cmp__ method instead of rich comparisons on Python 2. It's int.__cmp__.