Event handling in Ruby

i want to be able to do event handling with ruby. I know there is no native开发者_如何转开发 way to do this, but i found a solution here in stackoverflow:

class EventBase
    def initialize
        @listeners = Hash.new
    end

    def listen_event(name, *func, &p)
        if p
            (@listeners[name] ||= Array.new) << p
        else
            (@listeners[name] ||= Array.new) << func[0]
        end
    end

    def ignore_event(name, func)
        return if !@listeners.has_key?(name)
        @listeners[name].delete_if { |o| o == func }
    end

    def trigger_event(name, *args)
        return if !@listeners.has_key?(name)
        @listeners[name].each { |f| f.call(*args) }
    end
end


class MyClass < EventBase
    def raise_event1(*args)
        trigger_event(:event1, *args)
    end

    def raise_event2(*args)
        trigger_event(:event2, *args)
    end
end

class TestListener
    def initialize(source)
        source.listen_event(:event1, method(:event1_arrival))
        source.listen_event(:event2) do |*a|
            puts "event 2 arrival, args #{a}"
        end
    end

    def event1_arrival(*a)
        puts "Event 1 arrived, args #{a}"
    end
end

The problem is this: 1- It seems when you add a method to the listen array it executes right away 2- When the event triggers, it throws a NoMethodError: undefined method call for nil:NilClass

I am new to ruby so i dont understand the code completly, i feel its missing some pieces of code lol... (mostly because i dont know all ruby syntax) thanks

Some questions: - What means &p ? - What is ||=? - what means <

I think you may be trying to reinvent the wheel here. I would recommend using Observable instead. It's in the standard library, just require "observer" and include the Observable module into your class.

If you want to do event handling in a small Ruby script (ie: NOT a web application), then I recommend using the Unobservable gem (as in: it's NOT the Observable gem, har har har). You can find some basic details / links about the gem here:

https://briandamaged.org/blog/?p=1074

https://briandamaged.org/blog/?p=1161

This gem makes it easy to define multiple events in a single object. For example:

require 'unobservable'

class Button
  include Unobservable::Support

  attr_event :clicked
  attr_event :double_clicked

  def click(x, y)
    raise_event(:clicked, x, y)
  end

  def double_click(x, y)
    raise_event(:double_clicked, x, y)
  end
end

button  = Button.new
button.clicked.register {|x, y| puts "You just clicked: #{x} #{y}"}

button.click(2, 3)

Lol, ok i solved the problem... i wasnt calling listen_event correctly...

it should be listen_event(:indexChanged,method(:sayIndex)) not listen_event(:indexChanged,sayIndex(:index))

still learnin the ropes on ruby lol