CSC/ECE 517 Fall 2009/wiki2 4 va

Introduction

The IF statement is a conditional language structure, has been available to programmers for quite some time. It was first introduced in FORTRAN in a form of an arithmetic IF statement back in 1957 . While it may not be the same IF statement we know today,

Use of IF statements

class Vehicle
  def initialize
    puts "I am a vehicle"
  end
end

class Car < Vehicle
  def initialize
    super
    puts "I am a passenger car"
  end
end

class Truck < Vehicle
  def initialize
    super
    puts "I am a commercial truck"
  end 
end

class Driver
  puts "Do you have a Car or a Truck?" 
  #Expects Car or Truck, case sensitive
  type = gets             
  my_car = eval(type).new

  if my_car.class == Car
    puts "I like 87 octane gasoline"
  elsif my_car.class == Truck
    puts "I like diesel"
  end
end

Use of polymorphism

class Vehicle
  def initialize
    puts "I am a vehicle"
  end
end

class Car < Vehicle
  def initialize
    super
    puts "I am a passenger car"
  end
  
  def get_type_of_fuel
    "I like 87 octane gasoline"
  end
end

class Truck < Vehicle
  def initialize
    super
    puts "I am a truck"
  end
  
  def get_type_of_fuel
    "I like diesel"
  end
end

class Driver
  puts "Do you have a Car or a Truck?" 
  #Expects Car or Truck, case sensitive
  type = gets
  my_car = eval(type).new
  puts my_car.get_type_of_fuel  
end