Question on default value of __init__

[Bernie]

Hello all,

When I run test.py, an instance of foo is created.  Is this the default behavior 
in Python for default value?  i.e. The value must be exist as an object.  Are 
there any way to delay the creation of foo() until bar() is created.

Bernie

test.py:

    class foo:
        def __init__( self, param=None):
            print 'executed!'
	    self.__param = param

        def __nonzero( self):
            if self.__param:
                return 1
            else:
                return 0

    class bar:
        def __init__( self, param=foo()):
            assert isinstance( param, foo), '"in" must be an instance of foo'
            pass