what is the difference between include and extend?

Question

could someone try to explain me in "baby language" (english is not my native language) what the difference between including and extending a module is? I think Jason explained it like this:

So by calling extend and passing in the module name, 6:00 instead of being mixed in to instances of the class, 6:04 extend mixes in to the class methods of the class. 6:11 It can be a little bit confusing. 6:13 Go ahead and try it on your own now using WorkSpaces.

so I guess basically, the question is, what is the difference between instances and methods of the class? I can't seem to wrap my head around it, or will this get clearer as we go along?

Answer 1 · 2017-09-23T10:41:27Z

September 23, 2017 10:41am

Hello, Isis! include provides instance methods for the class that mixes it in. extend provides class methods for the class that mixes it in. I have demonstrated how you can use class methods and mix it in the case below.

class SomeClass
extend SomeModule #If you want to mix class methods use 'extend'
@@class_variable = "I'm class var" #@@class_variable - area of visibility will be the class and all it's instances
  def self.class_method #pay attention, class methods starts from self
    @@class_variable
  end
end

SomeClass.class_method #=> "I'm class var"

Cheers! P.S.: sorry for my 'baby-english', it's not my native language too :)

Answer 2 · 2020-02-21T06:15:55Z

February 21, 2020 6:15am

probably late for you but useful to others coming here after me, I found this article helpful: https://www.geeksforgeeks.org/include-v-s-extend-in-ruby/ i think jason's video on this is not very clear :(

Welcome to the Treehouse Community

Looking to learn something new?

Isis van der Plas

Isis van der Plas

what is the difference between include and extend?

2 Answers

Vladislav Trotsenko

Vladislav Trotsenko

Enrica Fedeli-Jaques

Enrica Fedeli-Jaques