garbage collection - Python __del__ method for classes? -

i'm interested in adding hooks code when class (as opposed instance) garbage collected or otherwise falls out of memory. here example code:

def make_objects():     class a(type):         def __del__(cls):             print 'class deleted'     class b(object):         __metaclass__ =         def __del__(self):             print 'instance deleted'     b = b()  print 'making objects' make_objects() print 'finished' 

i hoping see:

• making objects
• instance deleted
• class deleted
• finished

but instead saw was:

• making objects
• instance deleted
• finished

if modify code explicitly call del b, makes no difference:

def make_objects():     class a(type):         def __del__(cls):             print 'class deleted'     class b(object):         __metaclass__ =         def __del__(self):             print 'instance deleted'     del b 

output:

• making objects
• finished

my question is: possible hook object being deleted? there preventing class b being deleted may not aware of?