Module: RGame::Engine::Signal::DSL

Included in:
Component, Node2D
Defined in:
lib/rgame/engine/signal.rb

Overview

Class-level DSL for declaring signal "slots" so a host class need not hand-write the connect-forwarding boilerplate. extend Engine::Signal::DSL, then:

signal :on_clicked               # a no-arg signal
signal :on_changed, ChangeSignal # a typed signal (Signal.define(:index, :value))

For :on_clicked this generates:

def on_clicked(&block) = on_clicked_signal.connect(&block) # public: subscribe, returns handle
def on_clicked_signal = (@on_clicked ||= type.new)         # private: the Signal, to emit on

The Signal is built lazily on first use, so the host wires nothing in #initialize; emit from inside the host via the private <name>_signal reader.

Instance Method Summary collapse

Instance Method Details

#signal(name, type = Signal.define) ⇒ Object 



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# File 'lib/rgame/engine/signal.rb', line 21

def signal(name, type = Signal.define)
  ivar = :"@#{name}"
  reader = :"#{name}_signal"

  define_method(reader) do
    instance_variable_get(ivar) || instance_variable_set(ivar, type.new)
  end
  private reader

  define_method(name) { |&block| send(reader).connect(&block) }
end