Self, Class & Module

- Gourav Tiwari

# Object self example:

class User

def initialize(name)

@name = name

end

def user_name

@name

end

end

john = User.new('John')

ram = User.new('Ram')

def ram.soul

'divine'

end

self -> Current Object

method_missing, superclass...

ram

Anonymous Class

superclass

Class def…

User Class

superclass

Class def...

Object Class

superclass

Class def...

BasicObject Class

superclass

Class def...

Kernel Module

Module def...

Unusual way of defining a class# class example:

User = Class.new do

def initialize(name)

@name = name

end

def user_name

@name

end

end

john = User.name('John')

ram = User.new('Ram')

def ram.soul

'divine'

end

Self# Class self example:

class User

# self is set here to User class

def initialize(name)

@name = name

end

def self.all

'All Users!'

end

end

method_missing, superclass...

User

Anonymous Class

superclass

Class def…

class Class

superclass

Class def...

Module Class

superclass

Class def...

BasicObject Class

superclass

Class def...

User Class

superclass

Class def...

Object Class

superclass

Class def...

Modules● are not classes

● do not have instances

● are objects of Module class

● have module methods and module constants

● mixes-in with classes

Modules: includemodule MyModule

def obj_id

"The object id is #{object_id}"

end

end

class User

include MyModule

end

ram = User.new

ram.obj_id

include makes a reference to module

ram

Anonymous Class

superclass

Class def…

User Class

superclass

Class def...

Object Class

superclass

Class def...

BasicObject Class

superclass

Class def...

Kernel Module

Module def...

Anonymous Class

superclass

Class def…

module MyModule

Class def…

Modules: extendmodule MyModule

def class_name

"The class name is #{name}"

end

end

class User

extend MyModule

end

User.class_name

user = User.new

user.extend MyModule

extend: includes module in Ano class

User

Anonymous Classinclude MyModulesuperclass

Class def…

class Class

superclass

Class def...

Module Class

superclass

Class def...

BasicObject Class

superclass

Class def...

User Class

superclass

Class def...

Object Class

superclass

Class def...

extend: includes module in Ano class

ram

Anonymous Classinclude MyModulesuperclass

Class def…

User Class

superclass

Class def...

Object Class

superclass

Class def...

BasicObject Class

superclass

Class def...

Kernel Module

Module def...

Anonymous Class

superclass

Class def…

module MyModule

Class def…

Thank You!