Example: Interface

An interface is a contract of what the classes can do. When a class implements an interface, it promises to provide implementation to all the abstract methods declared in the interface. An interface contains only public methods without implementation and possibly constants. For example, Shape class is an interface that provide methods to calculate area and perimeter of shapes. There is Circle class implements those methods. Circle class has only radius attribute.

If you generate code from diagram above, the extension will generate two separated .rb files. One file is an interface which is generated as a Ruby module.

shape.rb

module Shape
  def area
    # TODO(person name): Implement this method here.
  end

  def perimeter
    # TODO(person name): Implement this method here.
  end
end

circle.rb

require_relative 'shape.rb'

class Circle
  include Shape

  def initialize(radius)
    @radius = radius
  end

  private
    attr_accessor :radius

  def to_s
    "Your string representation of the object will be written here."
  end
end

Note that the example use default configuration of the extension.