Module: Dataflow::EventMixin::ClassMethods

Defined in:
lib/dataflow/event_mixin.rb

Instance Method Summary collapse

Instance Method Details

#event(event_name) ⇒ Object 



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# File 'lib/dataflow/event_mixin.rb', line 7

def event(event_name)
  # re-open the base class
  handlers_var_name = "@#{event_name}_handlers"

  # Defines a class method called "event_name".
  # It will serve a global-level evt handler for this class.
  # @yield (optional) the event handler to add
  # @return Array the list of event handlers
  define_singleton_method(event_name) do |&block|
    handlers = instance_variable_get(handlers_var_name)

    unless handlers
      handlers = []
      instance_variable_set(handlers_var_name, [])
    end

    if block.present?
      handlers << block
      instance_variable_set(handlers_var_name, handlers)
    end

    # return all events from the hierarchy
    superclass_handlers = []
    superclass = self.superclass
    while superclass
      superclass_handlers += superclass.instance_variable_get(
        :"@#{event_name}_handlers"
      ) || []
      superclass = superclass.superclass
    end

    handlers + superclass_handlers
  end

  # Defines a method called "event_name".
  # It will serve a instance-level evt handler.
  # @yield (optional) the event handler to add
  # @return Array the list of event handlers
  define_method(event_name) do |&block|
    handlers = instance_variable_get(handlers_var_name)

    unless handlers
      handlers = []
      instance_variable_set(handlers_var_name, [])
    end

    if block.present?
      handlers << block
      instance_variable_set(handlers_var_name, handlers)
    end

    handlers
  end

  # Defines a way to fire the event: "on_event_name(evt)"
  # @param *args a variable list of arguments passed to the handlers
  define_method("on_#{event_name}") do |*args|
    handlers = send(event_name) + self.class.send(event_name)
    handlers.each do |handler|
      begin
        handler.call(self, *args)
      rescue StandardError => e
        @logger&.error(error: e, custom_message: "ERROR IN HANDLER [on_#{event_name}]")
        # ignore error in handlers
      end
    end
  end
end