slots

In the Python data model reference section on slots there is a list of notes on using __slots__ . I am thoroughly confused by the 1st and 6th items, because they seem to be contradicting each other. First item: When inheriting from a class without __slots__ , the __dict__ attribute of that class will always be accessible, so a __slots__ definition in the subclass is meaningless. Sixth item: The action of a __slots__ declaration is limited to the class where it is defined. As a result, subclasses will have a __dict__ unless they also define __slots__ (which must only contain names of any

I am trying to accurately/definitively find the size differences between two different classes in Python. They are both new style classes, save for one not having slots defined. I have tried numerous tests to determine their size difference, but they always end up being identical in memory usage. So far I have tried sys.GetSizeOf(obj) and heapy's heap() function, with no positive results. Test code is below: import sys from guppy import hpy class test3(object): def __init__(self): self.one = 1 self.two = "two variable" class test4(object): __slots__ = ('one', 'two') def __init__(self): self