title: How to use table listeners in corona sdk and how it works?
body: <p>can any one explain to me table listeners ? how to use it? when and why?
  and explain to me the following code </p>
  
  <pre><code>local object = display.newImage( "ball.png" )
  object.id = "ball object"
  
  local function onObjectTouch( self, event )
      if event.phase == "began" then
          print( "Touch event began on: " .. self.id )
      end
      return true
  end 
  
  object.touch = onObjectTouch
  object:addEventListener( "touch", object )
  </code></pre>