classes_and_methods.md

Classes and Methods

A class in Ruby is defined using the class keyword. Methods are defined using the def keyword.

class Employee
  def initialize(name, pay)
    @name = name
    @pay = pay
  end
  
  def to_s
    return "Employee: #@name, #@pay"
  end

emp1 = Employee.new("Jan Doe" , 409)
puts emp1.to_s #Employee: Jan Doe, 409
puts emp1 #Employee: Jan Doe, 409

@variableName is an instance variable, meaning, variables inside class. In the example, emp1 is an object. When puts is called on the object, it tries to convert the object to string. A function to_s exists in the class. This overrides the default function of Ruby to_s which is used to convert a primitive data type to string. Hence the last and second last line give the same output. Had there been no to_s method in the class, the last line in the example would have printed a reference to the object, similar to #<Employee 0x25ddef4>.

class Employee
  def initialize(name, pay)
    @name = name
    @pay = pay
  end
  
  def to_s
    return "Employee: #@name, #@pay"
  end
  attr_reader :name, :pay
  
  def name=(value)
    @name = value
  end
  def pay=(value)
    @name=value
  end
  
  #an instance method, called using the dot operator
`  def getPaid(hours)
    return @pay*hours
  end
end

emp1 = Employee("XYZ", 12.00)
puts "Name: ", emp1.name
puts "Pay rate: ", emp1.pay
puts "Amount paid: ", emp1.getPaid(40)