how to get "not regular" timer based events?

Comments

• atilim Maintainer

  February 2013 Accepted Answer

  I would use a single ENTER_FRAME event and check os.timer() * 1000 > table values (instead of ==). Here is a simple code:

  local t = {122, 623, 1358, 3560, 3563} local i = 1 local start = os.timer()   local function onEnterFrame() local msec = (os.timer() - start) * 1000 if i <= #t and msec > t[i] then print(t[i]) i = i + 1 end end   stage:addEventListener(Event.ENTER_FRAME, onEnterFrame)

  http://en.wikipedia.org/wiki/Cytorus

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• pie Member

  March 2013

  Thank you @atlim
  
  
  It's not that much different from my code, but this works!
  this is a lesson of logic flow to me.
  
  I still have a couple of questions about coding in general, from my begginer point of view:
  
  1) about your choice to use #t directly in the conditional statement:
  could this be considered a "best practice"?
  I used the same syntax, but in a new variable (declared previously).
  Is it better to keep the number of variables low for better performance?
  
  2) about the use of "local": when should I use it?
  is there a general rule/ reason to avoid or use this before variables and functions?
  
  Thank you very much, have a wonderful day!
  

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• ar2rsawseen Maintainer

  March 2013

  1) probably in this case it would be better to safe the size of table in a separate variable (of course if table size does not change). But you won't see the difference with such a small table
  
  2) you define local variable when you want to exist only in this specific scope.
  But in @atilim example, i is defined outside onEnterFrame event for simple reason, creating new variable consumes resources, and as onEnterFrame is calles so many times, it would be efficient to create one local variable outside the scope and reuse it in the event again and again. Usually you would define it as a property of a class where event method exists

  http://appcodingeasy.com/Gideros-Mobile

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• pie Member

  March 2013

  Thank you very much for your explanation:
  let me check if I understood you correctly:
  
  does it make some sense to write it like this?

  function scene:init() self:addEventListener(Event.ENTER_FRAME, self.onEnterFrame) self.start = os.timer() self.i = 1 end     function scene:onEnterFrame() if --blah blah? end end

  So in this specific example "local" and "self." have the same meaning or there is something else?
  
  I'm not sure if I got the definition of "scope", please correct me if I am wrong:
  scope is almost "everything", i.e. from "function scene:init()" to "end", but it could also be "global" as "the space" outside each function.
  
  Each scope is a separate entity where local variables are valid only "locally", BUT, if variables are set as propery of a class (like self.i) could be accessed from any method of the same function (init, EnterFrame in this example)?
  Could a property be "local"?

  function scene:init() self:addEventListener(Event.ENTER_FRAME, self.onEnterFrame) local self.start = os.timer() local self.i = 1 end

  
  sorry for my basic (and probably boring) questions, as soon as I learn enough to "walk alone" I'll certainly ask something more interesting...
  
  thank you again

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• ar2rsawseen Maintainer

  March 2013 Accepted Answer

  you understood the concept of local and self correctly and no self.propety can not be local, because self is instance (object available accross all methods) and by defining local self you will probably redefine internal reference to instance for that specific method

  http://appcodingeasy.com/Gideros-Mobile

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