Python 3 Object-Oriented Programming - Third Edition

Sorting lists

Without any parameters, sort will generally do as expected. If it's a list of strings, it will place them in alphabetical order. This operation is case sensitive, so all capital letters will be sorted before lowercase letters; that is, Z comes before a. If it's a list of numbers, they will be sorted in numerical order. If a list of tuples is provided, the list is sorted by the first element in each tuple. If a mixture containing unsortable items is supplied, the sort will raise a TypeError exception.

If we want to place objects we define ourselves into a list and make those objects sortable, we have to do a bit more work. The special __lt__  method, which stands for less than, should be defined on the class to make instances ...