gistfile1.rb

module Termtter
  class Client
    def initialize
      @hooks = []
    end
    def add_hook(&block)
      p block_given?
      p block
      @hooks << block
    end
    def call_hooks
      @hooks.each do |h| h.call end
    end

    @@singleton = self.new
    def self.method_missing(a, *args, &block)
      @@singleton.__send__(a, *args, &block)
    end
  end
end

Termtter::Client.add_hook do
  puts 'hook called'
end

Termtter::Client.call_hooks