I'll Be Backend
Search lessons / @illbebackend
Principles

Law of Demeter: Break the Getter Chain

The Law of Demeter says a method talks to its own fields, its parameters and the objects it creates, and not to the objects those hand back. A long getter chain breaks it, so one change deep inside a class breaks every caller that walks the chain. These lessons hide the delegate step by step until each caller talks only to the object it was given.

Pick your language

Law of Demeter: break the getter chain in Java, step 2: Memberships move into an accountJava · ~5 minLaw of Demeter in JavaLaw of Demeter: break the getter chain in C#, step 2: Memberships move into an accountC# · ~5 minLaw of Demeter in C#Law of Demeter: break the getter chain in Python, step 2: Memberships move into an accountPython · ~5 minLaw of Demeter in PythonLaw of Demeter: break the getter chain in PHP, step 2: Memberships move into an accountPHP · ~5 minLaw of Demeter in PHPLaw of Demeter: break the getter chain in TypeScript, step 2: Memberships move into an accountTypeScript · ~5 minLaw of Demeter in TypeScript

When to use it

Use it when

A class reaches through one object to get at another one's data, in more than one place.

Skip it when

The chain is a builder or a stream that returns a type you already use, or the objects are plain data records.

Spot it by

A line with several getters in a row, each called on what the last one returned.