Ivan Yurchenko wrote: > Hello. > > I've done the following in CPython 2.7.3 and 3.3.0 (and also in PyPy > 2.0b1): > >>>> import weakref >>>> x = set() >>>> y = weakref.proxy(x) >>>> x.__class__, type(x), isinstance(x, set) > (<class 'set'>, <class 'set'>, True) >>>> y.__class__, type(y), isinstance(y, set) > (<class 'set'>, <class 'weakproxy'>, True) > > So, type doesn't use object's __class__ to determine its class.
Sometimes it does: py> class X(object): pass ... py> class Y(object): pass ... py> x = X() py> x <__main__.X object at 0xb7c9adac> py> x.__class__ = Y py> x <__main__.Y object at 0xb7c9adac> py> type(x) <class '__main__.Y'> I believe that it depends on whether the instance being inspected is a heap-type (e.g. pure-Python object) or not. > I'm > looking for some CPyhton implementation details - how does class > identification with type() work? According to CPython's sources it looks > like there is a "marker" of actual object's class associated with each > PyObject - _typeobject struct, which is used to identify the class by > type(). Am I right? I'm not an expert on the CPython implementation, but I believe the code you want is buried somewhere in here: http://hg.python.org/cpython/file/tip/Objects/typeobject.c -- Steven -- http://mail.python.org/mailman/listinfo/python-list
