delegate

Ruby's delegate feature, implemented as Crystal macros.

Installation

Add this to your application's shard.yml:

dependencies:
  delegate:
    github: anicholson/delegate

Usage

require "delegate"

class Engine
  def state
    :stopped
  end
end

class Car
  include Delegate

  def initialize(@engine)
  end

  private getter engine

  delegate to: engine, methods: [state]
end

car = Car.new(Engine.new)

car.state # => :stopped

delegating to non-implemented methods results in a compile-time error:


require "delegate"

# ... Engine definition as before

class Motorbike
  def initialize(@engine)
  end

  private getter engine

  delegate to: engine, methods: [state, current_gear]
end

bike = Motorbike.new(Engine.new)
bike.current_gear # 💥 compile error: Engine does not implement :current_gear