What is the difference between include and require in Ruby?

Use the include Method in Ruby

Unlike require , which loads an entire file's code, include takes a module name and makes all its methods available to other classes or modules.

What is the use of require in Ruby?

In Ruby, the require method is used to load another file and execute all its statements. This serves to import all class and method definitions in the file.

What is difference between include and extend 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 does include work in Ruby?

What is include in Ruby on Rails?

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

#29 Ruby Tutorial - Require and Require Relative statements in Ruby

What is difference between joins and include in Rails?

:joins uses inner join, :includes uses outer join. the main reason of :includes is eager loading, to avoid the N+1 problem of loading in attributes of each object using a separate query.

Can I include a class in Ruby?

include is the most used and the simplest way of importing module code. When calling it in a class definition, Ruby will insert the module into the ancestors chain of the class, just after its superclass.

How do I 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' .

Can a module include a module Ruby?

Actually, Ruby facilitates the use of composition by using the mixin facility. Indeed, a module can be included in another module or class by using the include , prepend and extend keywords.

What is :: in Ruby?

The :: is a unary operator and is used to access (anywhere outside the class or module) constants, instance methods and class methods defined within a class or module. Note: In Ruby, classes and methods may be considered constants too.

What is the difference between include and extend relationship?

The include relationship supports the reuse of functionality in a use-case model. In UML modeling, you can use an extend relationship to specify that one use case (extension) extends the behavior of another use case (base).

What is a singleton class in Ruby?

Singleton is a creational design pattern, which ensures that only one object of its kind exists and provides a single point of access to it for any other code. Singleton has almost the same pros and cons as global variables. Although they're super-handy, they break the modularity of your code.

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 is %W in Ruby?

%w(foo bar) is a shortcut for ["foo", "bar"] . Meaning it's a notation to write an array of strings separated by spaces instead of commas and without quotes around them. You can find a list of ways of writing literals in zenspider's quickref.

What is module 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. Important Points about Modules: You cannot inherit modules or you can't create a subclass of a module. Objects cannot be created from a module.

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.

What is self method in Ruby?

self is a special variable that points to the object that "owns" the currently executing code. Ruby uses self everwhere: For instance variables: @myvar. For method and constant lookup. When defining methods, classes and modules.

What does Attr_accessor mean in Ruby?

Nouman Abbasi. In Ruby, object methods are public by default, while data is private. To access and modify data, we use the attr_reader and attr_writer . attr_accessor is a shortcut method when you need both attr_reader and attr_writer .

How do you inherit a class in Ruby?

In Ruby, single class inheritance is supported, which means that one class can inherit from the other class, but it can't inherit from two super classes. In order to achieve multiple inheritance, Ruby provides something called mixins that one can make use of.

What is the difference between load and require?

rb file every time the load function is called. 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.

What are the data types in Ruby?

What is class self in Ruby?

Class Method Self

A class method is a method that refers only to that class in all contexts, but not to any individual instances of that class. A class instance method is a method that applies to all instances of that class, but not for the class object itself.

What is proc and lambda in Ruby?

In Ruby, a lambda is an object similar to a proc. Unlike a proc, a lambda requires a specific number of arguments passed to it, and it return s to its calling method rather than returning immediately. def proc_demo_method. proc_demo = Proc. new { return "Only I print!" }

Is nil an object in Ruby?

However, in terms of how it's implemented, nil is fundamentally different than in other languages. In Ruby, nil is—you've guessed it—an object. It's the single instance of the NilClass class. Since nil in Ruby is just an object like virtually anything else, this means that handling it is not a special case.

What is eager loading rails?

Eager loading solves this problem by creating a left outer join on the table, returning all of the data in a single query. Adding an eager load is as simple as adding an :includes statement to the controller.