advanced-oop-notes.md

Homework & Questions

• OOP Review + Examples
• Class methods vs. Instance methods?
• What does the keyword super do?

Stubbing

We briefly discussed what happens when RSPEC stubs a method and why we need to use the attr_reader in order to check values if a instance variable method reader has been stubbed.

Here are some questions we discussed:

• What is stubbing?
• Why do we use it?
• How does stubbing effect how we write code?

Modules

Modules are defined similarly to classes, and can contain methods. However, modules are not bound to a data set the way an instance of a class would be. Modules add functionality and extend classes. Modules should also be treated as re-usable sets of methods that could be added to multiple classes.

Code:

module FUNC
  PI = 3.14

  def print_the_name
    puts "The name is #{@name}"
  end

  def count_to(num)
    (0..num).each do |current|
      puts "Current number is #{current}"
    end
  end
end

class Parent
  include FUNC

  def initialize(name)
    @name = name
  end
end

# instantiate a parent
parent = Parent.new("Sarah")
# call module method from instance
parent.count_to(10)

# instantiate a parent
child = Child.new("Johnny")

# namespacing with a module / class
puts "pie is #{Child::PI}"
puts "pie is #{FUNC::PI}"

Inheritance

We also demonstrated that modules can affect inheritance. Once a module is included in a class, it can affect the inheritance chain, particularly if the Module contains an initialize method.

Code:

module FUNC
  PI = 3.14

  def print_the_name
    puts "The name is #{@name}"
  end

  def count_to(num)
    (0..num).each do |current|
      puts "Current number is #{current}"
    end
  end
end

class Parent
  include FUNC

  def initialize(name)
    @name = name
  end
end

child.rb

class Child
	attr_reader :name
	PI = 4

	def initialize(name)
		@name = name
	end
end

func.rb

module FUNC
	PI = 3.14

	def print_the_name
		puts "The name is #{@name}"
	end

	def count_to(num)
		(0..num).each do |current|
			puts "Current number is #{current}"
		end
	end
end

main.rb

require_relative('func')
require_relative('parent')
require_relative('child')

# instantiate a parent
parent = Parent.new("Sarah")
# call module method from instance
parent.count_to(10)

# instantiate a parent
child = Child.new("Johnny")

# namespacing with a module / class
puts "pie is #{Child::PI}"
puts "pie is #{FUNC::PI}"

parent.rb

class Parent
	include FUNC

	def initialize(name)
		@name = name
	end
end