Python Standard Library

The UserList Module

The UserList module contains a list class that can be subclassed (simply a Python wrapper for the built-in list type).

In Example 2-16, AutoList instances work just like ordinary lists, except that they allow you to insert items at the end by assigning to them.

Example 2-16. Using the UserList Module

File: userlist-example-1.py

import UserList

class AutoList(UserList.UserList):

    def _ _setitem_ _(self, i, item):
        if i == len(self.data):
            self.data.append(item)
        else:
            self.data[i] = item

list = AutoList()

for i in range(10):
    list[i] = i

print list

[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]