Enum Basics

In this lesson you will learn to reproduce an enum in Ruby with a module, so a fixed set of options can be handled safely. This is for anyone searching for "Ruby enum how to use".

Ruby has no dedicated enum syntax, but gathering constants inside a module reproduces one. Use it when you want to limit the possible values in advance, the way a traffic light only has red, green, and amber.

The sample code defines three constants - RED, GREEN, BLUE - inside a Color module as symbols (values such as :red). Notice how they are referenced with ::, as in Color::RED.

A common stumbling block for beginners is the difference between a symbol and a string. A symbol such as :red looks like a string but is handled differently internally, including in comparison performance. Ruby uses symbols heavily for fixed values like these.

A named constant conveys intent far better than a string or a number scattered through the code, and it also guards against typos.