考慮以下：
In [1]: import types
In [2]: class A:
...: pass
...:
In [3]: a1 = A()
In [4]: a1.a, a1.b, a1.c = 1, 2, 3
In [5]: a2 = types.SimpleNamespace(a=1,b=2,c=3)
In [6]: sys.getsizeof(a1)
Out[6]: 56
In [7]: sys.getsizeof(a2)
Out[7]: 48
尺寸差異來自何處？看着：
In [10]: types.__file__
Out[10]: '/Users/juan/anaconda3/lib/python3.5/types.py'
我發現：
import sys
# Iterators in Python aren't a matter of type but of protocol. A large
# and changing number of builtin types implement *some* flavor of
# iterator. Don't check the type! Use hasattr to check for both
# "__iter__" and "__next__" attributes instead.
def _f(): pass
FunctionType = type(_f)
LambdaType = type(lambda: None) # Same as FunctionType
CodeType = type(_f.__code__)
MappingProxyType = type(type.__dict__)
SimpleNamespace = type(sys.implementation)
好吧,這什麼都沒做：
>>> import sys
>>> sys.implementation
namespace(cache_tag='cpython-35', hexversion=50660080, name='cpython', version=sys.version_info(major=3, minor=5, micro=2, releaselevel='final', serial=0))
>>> type(sys.implementation)
我似乎在這裡追逐自己的尾巴.
我在64位系統上使用CPython 3.5.對于一些我無法查明的錯誤引用,這8個位元組似乎正好合适.