how to remove a not fully know event listener ?

Comments

• ar2rsawseen Maintainer

  August 2012

  hello @nat12
  it should be:

  self:hasEventListener("clickUp")

  and not

  self.hasEventListener("clickUp")

  use colon insetad of dot

  http://appcodingeasy.com/Gideros-Mobile

  +1 -1Share on Facebook
• zvardin Member

  August 2012

  I was curious about this before as well. Is there any way to fetch all event listeners of a certain type on an object?

  +1 -1Share on Facebook
• zvardin Member

  August 2012

  @ar2rsawseen I think @nat12 is referring to that you need to have the function and data passed to an added event listener to remove it, but what if at the time I want to remove an event listener, I don't have a direct reference to them?
  
  for example:

  btn:addEventListener("clickUp", function() doSomething end, {foo=1,bar=2})

  +1 -1Share on Facebook
• ar2rsawseen Maintainer

  August 2012 edited August 2012 Accepted Answer

  haha, silly me.
  Yep got it now. But unfortunately there is no way, at least I don't know one.
  You need to pass exactly the same parameters to remove event listener. Same thing goes in javascript. But unless you pass the correct function, it does not know which function to remove (if for example you have multiple of them).
  
  @nat12 how could user actually add event?
  
  well usually you save the event handler (and all needed parameters) as property of class, like:

  btn.clickUp = function() doSomething end btn.clickUpParams = {foo=1,bar=2} btn:addEventListener("clickUp", btn.clickUp, btn.clickUpParams)   -- and then to remove btn:removeEventListener("clickUp", btn.clickUp, btn.clickUpParams)

  http://appcodingeasy.com/Gideros-Mobile

  +1 -1Share on Facebook
• techdojo Guru

  August 2012 Accepted Answer

  My solution is like @ar2sawseen's - in my custom button class I have a reference to a callback function that is passed when the button is created. Then when the button is pressed the custom callback function is called so that the function that called the button know's when it's been pressed - this neatly hides all the messy lower level event "twiddling" code and leaves a nice clean high level interface, literately

  local thisButtonsID = 1   local function wasPressed(button) print("Button "..button.id.." was pressed") end   myButton = CustomButton( { ... id = thisButtonsID, callback = wasPressed ... } )

  Note : That's just a bit of psuedo code, when creating a custom ui control I usually pass my data in as a table - but you should get the idea.

  WhiteTree Games - Home, home on the web, where the bits and bytes they do play!
  #MakeABetterGame! "Never give up, Never NEVER give up!" - Winston Churchill

  +1 -1Share on Facebook
• nat12 Member

  August 2012

  I was hoping there was some way to read back the datas from the EventDispatcher instead to duplicate them in the button class.
  
  I tried to code a generalization of what ar2rsawseen and techdojo suggested
  
  function Button:addListener(type, listener, data)
  table.insert(self.listenersTable, { t = type, l = listener, d = data } )
  self:addEventListener(type, listener, data)
  end
  
  function Button:removeListeners()
  for i = 1, #self.listenersTable do
  local data = self.listenersTable[i]
  self:removeEventListener(data.t, data.l, data.d)
  end
  end
  
  (Atilim, if you are reading, any chance to have a removeAllListeners() function added to EventDispather in near future?)

  Likes: techdojo

  +1 -1 (+1 / -0 )Share on Facebook