Module for implementing the service object pattern that allows for custom 'verbs'

call_me.md

A module for implementing the Service Object pattern that allows for custom "verbs".

Usage

Including CallMe in your class adds a call class method that instantiates an object of the class using the provided arguments and invokes its call method. For example:

Thing = Struct.new(:value) do
  include CallMe

  def call
    puts value
  end
end

Thing.call(123)
# => "123"

If you would prefer a verb other than call, then use CallMe.with(:your_verb):

Thing = Struct.new(:value) do
  include CallMe.with(:say)

  def say
    puts value
  end
end

Thing.say(123)
# => "123"

with is aliased to [], so you can use CallMe[:verb] instead of CallMe.with(:verb) if you prefer.

One final note: while the examples all use include, you can also use extend.

call_me.rb

module CallMe
  class << self
    def included(base)
      base.include with(:call)
    end

    def with(verb)
      callable_modules[verb.to_sym] ||= Module.new do
        define_singleton_method(:included) do |base|
          base.define_singleton_method(verb) do |*args|
            new(*args).public_send(verb)
          end

          base.define_singleton_method(:to_proc) do
            method(verb).to_proc
          end
        end
      end
    end

    alias [] with

    def callable_modules
      @callable_modules ||= {}
    end
  end
end