What is require in Ruby?

In Ruby, the require method is used to load another file and execute all its statements. … In addition to simply executing all of the statements in the file, the require method also keeps track of which files have been previously required and, thus, will not require a file twice.

How do you require a class in Ruby?

To put a class in a separate file, just define the class as usual and then in the file where you wish to use the class, simply put require ‘name_of_file_with_class’ at the top. For instance, if I defined class Foo in foo. rb , in bar. rb I would have the line require ‘foo’ .

What is the use of load and require in Ruby?

You should use load function mainly for the purpose of loading code from other files that are being dynamically changed so as to get updated code every time. Require reads the file from the file system, parses it, saves to the memory, and runs it in a given place.

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What happens when you require a file in Ruby?

When a file is required, all the constants from that file (classes, modules, and regular constants) are added to the Object class in the current file. … There is absolutely nothing special whatsoever going on, not with constants nor with any other thing. The code is just ran the exact same way as any other Ruby code.

What is the difference between require and Require_relative Ruby?

require_relative requires a file specifically pointed to relative to the file that calls it. require requires a file included in the $LOAD_PATH.

How do you require a gem?

Activating a gem adds that gem’s lib directory to the load path, which will then make requiring any of that gem’s files possible. Once the gem is activated, this require method tries to require the path once more. Due to the gem being activated, it is now possible to require ‘active_support/all’ .

What is include in Rails?

Rails provides an ActiveRecord method called :includes which loads associated records in advance and limits the number of SQL queries made to the database. This technique is known as “eager loading” and in many cases will improve performance by a significant amount.

What are rails concerns?

A Rails Concern is any module that extends ActiveSupport::Concern module. You might ask — how are concerns so different from modules?

What is module in Ruby?

Ruby module is a collection of methods and constants. A module method may be instance method or module method. Instance methods are methods in a class when module is included. … They are similar to classes as they hold a collection of methods, class definitions, constants and other modules. They are defined like classes.

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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.

How do I require a Ruby gem?

Requiring code

When you require a gem, really you’re just placing that gem’s lib directory onto your $LOAD_PATH . Let’s try this out in irb and get some help from the pretty_print library included with Ruby. Tip: Passing -r to irb will automatically require a library when irb is loaded.

What is mixin in Ruby?

Mixins in Ruby allows modules to access instance methods of another one using include method. Mixins provides a controlled way of adding functionality to classes. The code in the mixin starts to interact with code in the class. In Ruby, a code wrapped up in a module is called mixins that a class can include or extend.

How do you use include in Ruby?

include? is a String class method in Ruby which is used to return true if the given string contains the given string or character.

  1. Syntax: str. include?
  2. Parameters: Here, str is the given string.
  3. Returns: true if the given string contains the given string or character otherwise false.

What is autoload in Ruby?

Ruby has an in-built module autoload, which comes into action whenever a specific module or a class is accessed or called upon from the parent or calling class or module. Upon receiving a call, this module registers the corresponding file path to the called module.

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What is the purpose of load Auto_load and Require_relative in Ruby?

-Auto_load: this initiates the method that is in hat file and allows the interpreter to call the method. -require_relative: allows the loading to take place of the local folders and files.

What is $Load_path in Ruby?

$LOAD_PATH is used for the exact same purpose. In ruby an identifier starting with a $ symbol is a global variable. $LOAD_PATH is an array of absolute paths i.e it stores the exact location of all the dependencies in the project.