The UserDict Module

The UserDict module contains a dictionary class that can be subclassed (it's actually a Python wrapper for the built-in dictionary type).

Example 2-15 shows an enhanced dictionary class, which allows dictionaries to be "added" to each other and initialized using the keyword argument syntax.

Example 2-15. Using the UserDict Module

File: userdict-example-1.py import UserDict class FancyDict(UserDict.UserDict): def _ _init_ _(self, data = {}, **kw): UserDict.UserDict._ _init_ _(self) self.update(data) self.update(kw) def _ _add_ _(self, other): dict = FancyDict(self.data) dict.update(b) return dict a = FancyDict(a = 1) b = FancyDict(b = 2) print a + b {'b': 2, 'a': 1}