Looking through the Python 3.4 source code, we find that the integer (long) type definition effectively looks like this (once the C macros are expanded): (查看原文)
Here PyObject_HEAD is the part of the structure containing the reference count, type code, and other pieces mentioned before.
Notice the difference here: a C integer is essentially a label for a position in memory whose bytes encode an integer value. A Python integer is a pointer to a position in memory containing all the Python object information, including the bytes that contain the integer value. This extra information in the Python integer structure is what allows Python to be coded so freely and dynamically. All this additional information in Python types comes at a cost, however, which becomes especially apparent in structures that combine many of these objects. (查看原文)
