id: 3130,1
title: Law of Demeter.
date: 2022-11-13

Law of Demeter.

Also called the Principle of Least Knowledge, the Law of Demeter enforces encapsulation by restricting what a method is allowed to talk to. It permits a method to send messages to four places:rL5

• Its own class instance or self.
• self‘s components or class/instance variables.
• Objects in its arguments.
• Objects it instantiates.

In other words, a method is not allowed to access the methods on the return values of those messages. Dot-chaining is therefore not allowed, and subsequent work must be delegated to other methods. This encourages a class to expose methods that exactly represent what its clients want rather than delegating work to them. This leads to more generalized/reusable behaviors, but can also add verbosity in the form of wrapper methods.