The same methods will work exactly the same way within modules. Throughout this book we talk about using methods of Module from within classes. Module is actually the superclass of Class, so every Ruby class is also a module. We cover the use of modules as packaged functionality for existing classes in Recipes 10.1 and 10.4. The Enumerable module isn’t supposed to be used on its own: it adds functionality to a class like Array or Hash. Modules are also used to package functionality for inclusion in classes. We cover this most basic use of modules in Recipes 10.5 and 10.7. Ruby’s Math module is a good example of a namespace: it provides an overarching structure for constants like Math::PI and methods like Math::log, which would otherwise clutter up the main Kernel namespace.

When a module is used as a container for objects, it’s called a namespace.

Get a free trial today and find answers on the fly, or master something new and useful. NOTE: This article has also been published on the Ruby Best Practices blog.Join the O'Reilly online learning platform. But since no technical decision should be made based on dogma or a blind-faith acceptance of community conventions, these notes hopefully provide the necessary evidence to help you make good design decisions on your own.

With the alternatives to extend self having unpleasant quirks, it’s no surprise that they’re quickly falling out of fashion in the Ruby world. While the ability to selectively define which methods can be called directly on the module is nice in theory, I’ve yet to see a use case for it where it would lead to a much better design. gsub ( //, '' ) end endįrom these examples, we see that module_function is more flexible than defining methods directly on your modules, but not nearly as versatile as extending a module with itself. any? do | e | normalize ( input ) =~ / # /i end end private def normalize ( input ) input. Module MinimalAnswer extend self def match? ( pattern, input ) pattern.

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