What is extend in Ruby?

What is extend in Ruby?

extend – adds the specified module’s methods and constants to the target’s metaclass (i.e. the singleton class) e.g. if you call Klazz.extend(Mod) , now Klazz has Mod’s methods (as class methods) if you call obj. extend(Mod) , now obj has Mod’s methods (as instance methods), but no other instance of of obj.

What’s the difference between extend prepend and include?

The only difference is where in the ancestor chain the module is added. With include , the module is added after the class in the ancestor chain. With prepend, the module is added before the class in the ancestor chain.

What does module do in Ruby?

In Ruby, modules are somewhat similar to classes: they are things that hold methods, just like classes do. However, modules can not be instantiated. I.e., it is not possible to create objects from a module. And modules, unlike classes, therefore do not have a method new .

What is the difference between a class and a module Ruby?

What is the difference between a class and a module? Modules are collections of methods and constants. They cannot generate instances. Classes may generate instances (objects), and have per-instance state (instance variables).

What does extend self do?

extend self includes all the existing instance methods as module methods. This is equivalent to saying extend Rake . Also Rake is an object of class Module . This can be used to define self contained modules with private methods.

How do you use extend in Ruby?

Extend is also used to importing module code but extends import them as class methods. Ruby will throw an error when we try to access methods of import module with the instance of the class because the module gets import to the superclass just as the instance of the extended module.

Why we use module in Rails?

Modules provide a structure to collect Ruby classes, methods, and constants into a single, separately named and defined unit. This is useful so you can avoid clashes with existing classes, methods, and constants, and also so that you can add (mix in) the functionality of modules into your classes.

What is the difference between extend and include in Ruby?

In simple words, the difference between include and extend is that ‘include’ is for adding methods only to an instance of a class and ‘extend’ is for adding methods to the class but not to its instance.

Is module a class in Ruby?

A Module is a collection of methods, constants, and class variables. Modules are defined as a class, but with the module keyword not with class keyword.