Best to use self.object or create local object ?

Comments

• OZApps Guru

  March 2014 Accepted Answer

  You can get different response to this one, however in my opinion here's how I look at it.

  local tempObj = self.Object print(tempObject)

  then using tempObj is one opcode in LuaVM whereas,

  print(self.Object)

  is equivalent of two opcodes, one to first get the global to get self and then to get object.
  
  If there were a couple of lines that would require access to self.Object, that would be slightly more intensive (if you are looking for critical and optimisation) otherwise it should not matter much really.
  
  Secondly, if you are going to encapsulate everything then fine, otherwise you would need some place to save the objects (animation, etc) which would ultimately need to be global. So you can access it by assigning it to a local variable for that function.
  
  To back this

  local object = self.object object = object + 1 object = object * 3 print(object)

  Translates to the following

  getglobal 0 0 ; self gettable 0 0 257 ; "object" add 0 0 258 ; 1 mul 0 0 259 ; 3 getglobal 1 4 ; print move 2 0 call 1 2 1

  and then

  self.object = self.object + 1 self.object = self.object * 3 print(self.object)

  would on the other hand translate to

  getglobal 0 0 ; self getglobal 1 0 ; self gettable 1 1 257 ; "object" add 1 1 258 ; 1 settable 0 257 1 ; "object" getglobal 0 0 ; self getglobal 1 0 ; self gettable 1 1 257 ; "object" mul 1 1 259 ; 3 settable 0 257 1 ; "object" getglobal 0 4 ; print getglobal 1 0 ; self gettable 1 1 257 ; "object" call 0 2 1

  as you can see that each time we use

  self.object

  that first gets the global self, then gets the table sub-item "object" while when we use local, it doesn't have to access the global table and sub item.

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• anneMurielle Member

  March 2014

  Thank you a lot for your explanation!

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• GregBUG Guru

  March 2014

  @OZApps
  nice!
  thanks!

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