1 files changed, 3 insertions, 7 deletions
diff --git a/lib/plum/event_emitter.rb b/lib/plum/event_emitter.rb
index 7bc9695..e0684dd 100644
--- a/lib/plum/event_emitter.rb
+++ b/lib/plum/event_emitter.rb
@@ -5,18 +5,14 @@ module Plum
     # @param name [Symbol] The name of event.
     # @yield Gives event-specific parameters.
     def on(name, &blk)
-      (callbacks[name] ||= []) << blk
+      @callbacks ||= {}
+      (@callbacks[name] ||= []) << blk
     end
 
     # Invokes an event and call handlers with args.
     # @param name [Symbol] The identifier of event.
     def callback(name, *args)
-      (cbs = callbacks[name]) && cbs.each {|cb| cb.call(*args) }
-    end
-
-    private
-    def callbacks
-      @callbacks ||= {}
+      @callbacks&.[](name)&.each { |cb| cb.call(*args) }
     end
   end
 end