Class Hashed

Lib/test/test_dict.py:503–512

    def test_setdefault_atomic(self):
        # Issue #13521: setdefault() calls __hash__ and __eq__ only once.
        class Hashed(object):
            def __init__(self):
                self.hash_count = 0
                self.eq_count = 0
            def __hash__(self):
                self.hash_count += 1
                return 42
            def __eq__(self, other):
                self.eq_count += 1
                return id(self) == id(other)
        hashed1 = Hashed()
        y = {hashed1: 5}
        hashed2 = Hashed()