如何在Ruby中做事件？

Question

我来自C#背景,刚刚开始用Ruby编程.问题是,我需要知道如何在我的课程中引发事件,以便在需要发生事情时触发各种观察者.

问题是我在Ruby上的书甚至没有提到事件,更不用说提供例子了.有人能帮助我吗？

Answer 1

这个问题已经得到了解答,但是如果你想看一下,那么在标准库中就有一个观察者.我过去曾经用过一个小游戏项目,而且效果很好.

Answer 2

极其简单的 Ruby 监听器。这并不完全是 .NET 事件的替代品，但这是一个非常简单的侦听器的极其简单的示例。

module Listenable

    def listeners() @listeners ||= [] end

    def add_listener(listener)
        listeners << listener
    end

    def remove_listener(listener)
        listeners.delete listener
    end

    def notify_listeners(event_name, *args)
        listeners.each do |listener|
            if listener.respond_to? event_name
                listener.__send__ event_name, *args
            end
        end
    end

end

使用方法：

class CowListenable
    include Listenable

    def speak
        notify_listeners :spoken, 'moooo!'
    end

end

class CowListener

    def initialize(cow_listenable)
        cow_listenable.add_listener self
    end

    def spoken(message)
        puts "The cow said '#{message}'"
    end

end

cow_listenable = CowListenable.new
CowListener.new(cow_listenable)
cow_listenable.speak

输出：

The cow said 'moooo!'

Answer 3

我尝试用 Ruby 编写一个 GUI 库，并使用一点 C，主要是 Ruby。结果太慢了，我放弃了，再也没有释放它。但我为它编写了一个事件系统，试图使其比 C# 的更容易。我重写了几次以使其更易于使用。我希望它有所帮助。

class EventHandlerArray < Array
  def add_handler(code=nil, &block)
    if(code)
      push(code)
    else
      push(block)
    end
  end
  def add
    raise "error"
  end
  def remove_handler(code)
    delete(code)
  end
  def fire(e)
    reverse_each { |handler| handler.call(e) }
  end
end

# with this, you can do:
#  event.add_handler
#  event.remove_handler
#  event.fire (usually never used)
#  fire_event
#  when_event
# You just need to call the events method and call super to initialize the events:
#  class MyControl
#    events :mouse_down, :mouse_up,
#           :mouse_enter, :mouse_leave
#    def initialize
#      super
#    end
#    def when_mouse_up(e)
#      # do something
#    end
#  end
#  control = MyControl.new
#  control.mouse_down.add_handler {
#    puts "Mouse down"
#  }
# As you can see, you can redefine when_event in a class to handle the event.
# The handlers are called first, and then the when_event method if a handler didn't
# set e.handled to true. If you need when_event to be called before the handlers,
# override fire_event and call when_event before event.fire. This is what painting
# does, for handlers should paint after the control.
#  class SubControl < MyControl
#    def when_mouse_down(e)
#      super
#      # do something
#    end
#  end
def events(*symbols)
  # NOTE: Module#method_added

  # create a module and 'include' it
  modName = name+"Events"
  initStr = Array.new
  readerStr = Array.new
  methodsStr = Array.new
  symbols.each { |sym|
    name = sym.to_s
    initStr << %Q{
      @#{name} = EventHandlerArray.new
    }
    readerStr << ":#{name}"
    methodsStr << %Q{
      def fire_#{name}(e)
        @#{name}.fire(e)
        when_#{name}(e) if(!e.handled?)
      end
      def when_#{name}(e)
      end
    }
  }
  eval %Q{
    module #{modName}
      def initialize(*args)
        begin
          super(*args)
        rescue NoMethodError; end
        #{initStr.join}
      end
      #{"attr_reader "+readerStr.join(', ')}
      #{methodsStr.join}
    end
    include #{modName}
  }
end

class Event
  attr_writer :handled
  def initialize(sender)
    @sender = @sender
    @handled = false
  end
  def handled?; @handled; end
end