class Test():
    def __init__(self, a, b):
        self.a = a
        self.b = b
    def __getitem__(self, key):
        return getattr(self, key)
    def __setitem__(self, key, value):
        setattr(self, key, value)

a=Test(1,2)
print(a.__dict__)
for x in a.__dict__:
    print(x)

for x in Test.__dict__:
    print(x)

def __iter__(self):
    return iter(self.__dict__)

>>> a = Test(5,6)
>>> print( *a )
a b