An optimized template to build an includible DSL in Ruby.

includible_dsl.rb

# frozen_string_literal: true

module Extension
  class T
    class O
    end
  end

  def self.foo(*args)
    p("bar #{args}")
  end
end

module Sugar
  def self.included(base)
    base.extend ClassMethods
  end

  module ClassMethods
    def const_missing(name)
      super unless Extension.const_defined?(name)

      const_set(name, Extension.const_get(name))
    end
  end

  def method_missing(name, *args, &block)
    super unless Extension.respond_to?(name)

    self.class.send(:define_method, name) { |*arrgs| Extension.send(name, *arrgs) }

    Extension.send(name, *args, &block)
  end

  def respond_to_missing?(name, include_all)
    return true if Extension.respond_to?(name)

    super
  end
end

class Main
  include Sugar

  def main
    foo
    foo(1)
    foo(1, 2)
    foo(1, test: true)
    p(T)
    p(T::O)
  end
end

Main.new.main