1. Subclassing Built-In Types Is Tricky
Since Python 2.2, subclassing built-in types such as list or dict can be done but there is a major caveat: the code of the built-ins (written in C) does not call special methods overridden by user-defined classes.
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Inheritance: For Good or For Worse
原文：https://www.cnblogs.com/neozheng/p/12359845.html