Expert Python Programming - Third Edition

Classes

The names of classes are always in CamelCase, and may have a leading underscore when they are private to a module.

In object-oriented programming classes are used to encapsulate the application state. Attributes of objects are record of that state. Methods are used to modify that state, convert it into meaningful values or to produce side effects. This is why class names are often noun phrases and form a usage logic with the method names that are verb phrases. The following code example contains a Document class definition with a single save() method:

class Document():    file_name: str    contents: str    ...        def save(self):        with open(self.file_name, 'w') as file:            file.write(self.contents)

Class instances often use the same noun phrases ...