Question

In python we can say:

if foo < bar < baz:
    do something.

and similarly, we can overload the comparision operators like:

class Bar:
    def __lt__(self, other):
        do something else

but what methods of the types of the operands of those interval comparisions are actually called? is the above equivalent to

if foo.__lt__(bar) and bar.__lt__(baz):
    do something.

Edit: re S.Lott, Here’s some output that helps to illustrate what actually happens.

>>> class Bar:
    def __init__(self, name):
        self.name = name
        print('__init__', self.name)
    def __lt__(self, other):
        print('__lt__', self.name, other.name)
        return self.name < other.name

>>> Bar('a') < Bar('b') < Bar('c')
('__init__', 'a')
('__init__', 'b')
('__lt__', 'a', 'b')
('__init__', 'c')
('__lt__', 'b', 'c')
True
>>> Bar('b') < Bar('a') < Bar('c')
('__init__', 'b')
('__init__', 'a')
('__lt__', 'b', 'a')
False
>>> 

Answer 1

You are correct:

class Bar:
    def __init__(self, name):
        self.name = name
    def __lt__(self, other):
        print('__lt__', self.name, other.name)
        return True

a,b,c = Bar('a'), Bar('b'), Bar('c')

a < b < c

Output:

('__lt__', 'a', 'b')
('__lt__', 'b', 'c')
True