Killing off an EventListener

ArtLeeApps · July 2013

HI all,

If i create "wordClass". like so:
wordClass = Word.new()

Then within "Word" i start a Listener....
self:addEventListener(Event.ENTER_FRAME, Word.onEnterFrame, self)

If then do this again...
wordClass = Word.new()

Does it kill off the first Listener ? or would making wordClass = nil remove the Listener.

ar2rsawseen · July 2013

@ArtLeeApps it will be basically the same, but most probably event won't be removed immediately, it would take some time to collect the previous instance.

OZApps · July 2013

@ArtLeeApps, like @ar2rsawseen said, it is totally dependent on the system as to when it is cleaned/garbagecollected.

However if it was a C variant, then if you allocate an object

0
wordClass = Word.new()  -- would allocate some memory, say 0xf00d0010
wordClass = Word.new()  -- would allocate some more memory, say 0xf00d0100
--[[
but there is no handler to the memory location 0xf00d0010
as it is now overwritten to point to 0xf00d0100 and this is
where memory leaks occur as the memory allocated is not
released. In Lua since memory management is managed by
the LuaVM, the memory is deallocated as <a href="http://forum.gideros.rocks/profile/ar2rsawseen" rel="nofollow">@ar2rsawseen</a>
mentioned when the GC is run.
--]]

Going by that theory, the listener would not be killed and not deallocated until it is no longer in use when GC runs.

Scouser · July 2013

@OZApps: Can you break that comment line down onto multiple lines as it goes off the screen and is unreadable.

ArtLeeApps · July 2013

@OZApps @ar2rsawseen, thanks, i think I'll kill off the old listener first, to be sure.

SinisterSoft · July 2013

@ArtLeeApps That's what I do too, never had a crash doing things that way.

OZApps · July 2013

@OZApps @ar2rsawseen, thanks, i think I'll kill off the old listener first, to be sure.

If you remove that child object from stage and it is not being referenced anywhere, GC will kill it along with the listener. So you can create a :destroy() function that kills all eventListeners, other objects if any and then removes it off the stage, so you can simply call myObj:destroy() and all done... or destroy(myObject) which would be a more generic function.

ArtLeeApps · July 2013

Thank you(s)...

What if make an"onExitBegin" for the removal.
does this get run, if i set the Variable to NIL ?

myThing = new.Thing()
-- some stuff
myThing = nil

function level:onExitBegin()
    self:removeEventListener(Event.ENTER_FRAME, self.onEnterFrame, self)
end

OZApps · July 2013

yes and no, it all depends on where and how you are using it. Ultimately software is all about what works for you, so if it works, good.

From a CS type focus where every thing that is allocated needs to be deallocated and dereferenced, etc, that might not be such a good idea. However maybe for what you are doing, perhaps your solution is exactly what you need.

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