# refcount.py

# Don't try these tricks with plain ints/strings: they get 
# special handling.

import sys

class C:
    def __del__(self):
        print "Bye-bye!"

# Two refcounts, because getrefcount() creates a reference
a = C()
print "References to a:", sys.getrefcount(a)

b = c = d = a
print "References to a:", sys.getrefcount(a)

del b
del c
print "References to a:", sys.getrefcount(a)

d = 1
print "References to a:", sys.getrefcount(a)

# Object vanishes, calling __del__()
del a


import gc
gc.disable()
gc.set_debug(gc.DEBUG_SAVEALL)

# Can't demo GC with __del__()
class C:
    pass

# Create a cycle
a = C()
b = C()
a.b = b
b.a = a

del a
del b

gc.collect()
print gc.garbage

# Break cycle -- don't rely on this ordering in real life!
del gc.garbage[1].b

# Need to reap the references in gc.garbage, too
del gc.garbage[:]

gc.collect()
print gc.garbage