Class _Sentinel

Lib/unittest/mock.py:326–338

Access attributes to return a named object, usable as a sentinel.

class _Sentinel(object):
    """Access attributes to return a named object, usable as a sentinel."""
    def __init__(self):
        self._sentinels = {}

    def __getattr__(self, name):
        if name == '__bases__':
            # Without this help(unittest.mock) raises an exception
            raise AttributeError
        return self._sentinels.setdefault(name, _SentinelObject(name))

    def __reduce__(self):
        return 'sentinel'


sentinel = _Sentinel()