Classes & Objects Review

classes_objects_essentials.rb

# Defining a new class

class Student
end

# Creating an instance of a class

> student = Student.new
> student.class
=> Student

# Defining an instance method in a class

class Student
  def shout
    puts "HEY!"
  end
end

# Invoking an instance method on a class

> student = Student.new
> student.shout
HEY!
=> nil

# Defining an attribute accessor on a class
# NOTE: This creates two methods for us: .name and .name=

class Student
  attr_accessor :name
end

> student = Student.new
> student.name
=> nil
> student.name = "Salman"
=> "Salman"
> student.name
=> "Salman"

# Using an attribute in an instance method

class Student
  attr_accessor :name

  def shout_name
    puts "HEY! Its me, #{@name}"
  end
end

> student = Student.new
> student.name = "Salman"
=> "Salman"
> student.shout_name
HEY! Its me, Salman
=> nil

# Defining a CLASS method on a class

class Student
  attr_accessor :name

  def self.race
    "Human"
  end

  def shout_name
    puts "HEY! Its me, #{@name}"
  end
end

> student = Student.new
> student.name
=> "Salman"
> student.shout_name
HEY! Its me, Salman
=> nil

> student.class
=> Student
> student.class.race
=> "Human"
> Student.race
=> "Human"