Add delegate_example for ex06

courses/ruby/ex06/delegate_example.rb

@@ -0,0 +1,110 @@
+RPM_TO_SPEED_MULTIPLIER = 10
+require "minitest/autorun"
+require "minitest/pride"
+require_relative "delegator.rb"
+class Tire # Part of Car
+  def initialize(producer:, diameter:)
+    @producer = producer    # String
+    @diameter = diameter    # String
+    @dirty = [true, false].sample # Random state
+  end
+
+  def dirty
+    @dirty
+  end
+end
+
+class Engine # Part of Car
+  def initialize(capacity:, horses:)
+    @capacity = capacity  # Integer
+    @horses = horses      # Integer
+    @rpm = 0              # Integer
+    @dirty = [true, false].sample # Random state
+    @is_electric = true # All engines are electric
+  end
+
+  def accelerate(kilometers)
+    # Lets say that our speed increase linearly with rotations per second.
+    @rpm += kilometers * RPM_TO_SPEED_MULTIPLIER # Convert speed into rpm
+  end
+
+  def horses
+    @horses
+  end
+
+  def rpm
+    @rpm
+  end
+
+  def is_electric? # Reader
+    @is_electric
+  end
+
+  def dirty
+    @dirty
+  end
+end
+
+class Car # Main class
+  include Enumerable
+  Module.prepend MyDelegate # Include my_delegate method
+  def initialize(name:, engine:, tires:) # Car consist of 3 parts: brand, engine and array of tires
+    @name = name
+    @engine = engine
+    @tires_pack = tires
+  end
+
+  my_delegate :rpm, :accelerate, :horses, :is_electric?, to: :@engine # Delegating Engine instance methods to instance variable @engine
+
+  my_delegate :each, :find, :find_all, to: :details # Delegating Enumerables into "details" Car instance method
+
+  my_delegate :capitalize, to: :@name #Delegating capitalize string method to @name instance variable
+
+  def engine #Reader
+    @engine
+  end
+
+
+  def speed #Reader
+    rpm * RPM_TO_SPEED_MULTIPLIER
+  end
+
+  def details # => Array
+    @tires_pack + [@engine]
+  end
+end
+
+class MyDelegateTest< Minitest::Test #Tests
+  def test_1
+    engine = Engine.new(capacity: 0, horses: 200)
+    tire1 = Tire.new(producer: :michelin, diameter: 17)
+    tire2 = Tire.new(producer: :michelin, diameter: 17)
+    tire3 = Tire.new(producer: :good_year, diameter: 18)
+    tire4 = Tire.new(producer: :good_year, diameter: 18)
+    c = Car.new(name: "Nissan", engine: engine, tires: [tire1, tire2, tire3, tire4])
+
+    assert_equal c.horses, 200
+    assert_equal c.capitalize, "Nissan".capitalize
+  end
+end
+
+engine = Engine.new(capacity: 0, horses: 200)
+tire1 = Tire.new(producer: :michelin, diameter: 17)
+tire2 = Tire.new(producer: :michelin, diameter: 17)
+
+tire3 = Tire.new(producer: :good_year, diameter: 18)
+tire4 = Tire.new(producer: :good_year, diameter: 18)
+
+c = Car.new(name: "Nissan", engine: engine, tires: [tire1, tire2, tire3, tire4])
+
+pp "INITIAL: speed: #{c.speed}"
+c.accelerate(10)
+pp "ACCELERATE 1: speed #{c.speed}, rpm: #{c.rpm}"
+c.accelerate(20)
+pp "ACCELERATE 2: speed #{c.speed}, rpm: #{c.rpm}"
+pp c.each {|detail| puts "Detail: #{detail}" }
+pp "Finding engine details:"
+pp c.find {|detail| detail.is_a?(Engine) }
+
+pp "Finding dirty details:"
+pp c.select(&:dirty)