EventEmitterをRubyで再実装

app.rb

require "./emitter.rb"

Emitter.once("hello") do |param|
  puts "Hello World #{param}"
end

Emitter.emit("hello", "param")
Emitter.emit("hello", "param2")

emitter.rb

class Emitter
  @handlers = []

  def self.on(key, &block)
    hander = {"#{key}" => {proc: block, once: false}}
    @handlers.push(hander)
  end

  def self.once(key, &block)
    hander = {"#{key}" => {proc: block, once: true}}
    @handlers.push(hander)
  end

  def self.off(key)
    @handlers.delete_if { |h| h.has_key?(key) }
  end

  def self.emit(key, params = {})
    call_handler = @handlers.find{ |h| h.has_key?(key) }
    if call_handler
      @handlers.delete_if { |h| h.has_key?(key) } if call_handler[key][:once]
      call_handler[key][:proc].call(params)
    else
      puts "Not Call Key: #{key}"
    end
  end
end