Class Uncollectable

Lib/test/test_gc.py:67–80

Create a reference cycle with multiple __del__ methods. An object in a reference cycle will never have zero references, and so must be garbage collected. If one or more objects in the cycle have __del__ methods, the gc refuses to guess an order, and leaves the cycle uncollected.

@with_tp_del
class Uncollectable(object):
    """Create a reference cycle with multiple __del__ methods.

    An object in a reference cycle will never have zero references,
    and so must be garbage collected.  If one or more objects in the
    cycle have __del__ methods, the gc refuses to guess an order,
    and leaves the cycle uncollected."""
    def __init__(self, partner=None):
        if partner is None:
            self.partner = Uncollectable(partner=self)
        else:
            self.partner = partner
    def __tp_del__(self):
        pass

if sysconfig.get_config_vars().get('PY_CFLAGS', ''):
    BUILD_WITH_NDEBUG = ('-DNDEBUG' in sysconfig.get_config_vars()['PY_CFLAGS'])