On 2/3/2015 1:12 PM, Jugurtha Hadjar wrote:
Hello,
I was writing something and thought: Since the class had some
'constants', and multiple instances would be created, I assume that each
instance would have its own data. So this would mean duplication of the
same constants? If so, I thought why not put the constants in memory
once, for every instance to access (to reduce memory usage).
Correct me if I'm wrong in my assumptions (i.e: If instances share stuff).
So I investigated further..
>>> import sys
>>> sys.getsizeof(5)
12
So an integer on my machine is 12 bytes.
Now:
>>> class foo(object):
... def __init__(self):
... pass
>>> sys.getsizeof(foo)
448
>>> sys.getsizeof(foo())
28
>>> foo
<class '__main__.foo'>
>>> foo()
<__main__.foo object at 0xXXXXXXX
- Second weird thing:
>>> class bar(object):
... def __init__(self):
... self.w = 5
... self.x = 6
... self.y = 7
... self.z = 8
>>> sys.getsizeof(bar)
448
>>> sys.getsizeof(foo)
448
>>> sys.getsizeof(bar())
28
>>> sys.getsizeof(foo())
28
>>> sys.getsizeof(bar().x)
12
>>> sys.getsizeof(bar().y)
12
Summary questions:
1 - Why are foo's and bar's class sizes the same? (foo's just a nop)
i'm not sure on this one.
2 - Why are foo() and bar() the same size, even with bar()'s 4 integers?
neither foo() nor bar() return anything explicitly, so both return the
default none
3 - Why's bar()'s size smaller than the sum of the sizes of 4 integers?
same as above.
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