Ruby – Difference between Require and Include

Ruby – Difference between Require and Include ?

While coding with Ruby or Ruby on Rails, you might have came across Require and Include. There are quite a few differences between Require and Include.

First of all let us see, what Require does in Ruby.
1. REQUIRE

Syntax:

require(name)

Returns: boolean (true/false)

Action
The name which is passed as parameter to the require, ruby will try to find the source file with that name in your load path.

What is load path?

The load path is the path from where library files for your program are loaded. You can see what is the load path for your programs by the following command.

> $load_path

This will list the load path i.e. locations from where library files are loaded.

If name which is passed as argument includes extension .rb then ruby will try to find the file with the same name and extension in the load path, otherwise i.e. If you do not provide the extension for the name then ruby will try to find the file with same name with .rb as it's extension. The name nay be given for the .dll, .so files.

Require also takes care of whether your files are previously loaded or not. Optimization is done based on this information.

You can try using require until you get comfortable with it.
2. INCLUDE

Syntax: include module_name

Action:
The include is another important feature provided by Ruby just to ensure DRY principle.

What is DRY?

If you don't know what is DRY, they you should start learning Ruby. The Don't Repeat Yourself (DRY) principle is provided by the ruby just to avoid avoid code duplicity, in fact any kind of duplicity.

Suppose if you have some methods that you need to have in two different classes. Then you don't have to write them in both the classes. Instead what you can do is, define it in module. And then include this module in other classes.

module RubyModule
 def put_message
    puts "Ruby in Rails is Amazing"
 end
end

Then, what you can do with this module is you can include it in any class where you would want the method put_message

For example,

class Person
include RubyModule
end

Then, ultimately class person gets equipped with the method that are include in the module named RubyModule.
These are the basic differences between use of Ruby Require and Ruby Include.