Module: RGame::Engine::Signal

Defined in:
lib/rgame/engine/signal.rb

Defined Under Namespace

Modules: DSL

Constant Summary collapse

IDENTIFIER = 
/\A[a-z_][a-zA-Z0-9_]*\z/

Class Method Summary collapse

Class Method Details

.define(*fields) ⇒ Object 



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# File 'lib/rgame/engine/signal.rb', line 34

def self.define(*fields)
  fields.each do |field|
    raise ArgumentError, "invalid field name: #{field.inspect}" unless field.to_s.match?(IDENTIFIER)
  end

  params = fields.size == 1 ? fields.first : fields.map { |f| "#{f}:" }.join(', ')
  args = fields.join(', ')

  Class.new do
    class_eval(<<~RUBY, __FILE__, __LINE__ + 1)
      # For fields [:x, :y] this generates:
      #   def initialize
      #     @listeners = []
      #   end
      #   def connect(&callback)
      #     @listeners << callback
      #     callback
      #   end
      #   def disconnect(handle) = @listeners.delete(handle)
      #   def emit(x:, y:)
      #     @listeners.each { it.call(x, y) }
      #   end

      def initialize
        @listeners = []
      end

      def connect(&callback)
        @listeners << callback
        callback
      end

      def disconnect(handle) = @listeners.delete(handle)
      def emit(#{params})
        @listeners.each { it.call(#{args}) }
      end
    RUBY
  end
end