Editing WoW:Using OnUpdate correctly (section)

== Proper Use Example ==
; your_xml_file.xml
 <Ui ...>
   <Frame ...>
     ...
     <Scripts>
       <OnLoad>self.TimeSinceLastUpdate = 0 </OnLoad>
       <OnUpdate function="MyAddon_OnUpdate" />      
     </Scripts>			
   </Frame>
 </Ui>
The important part for us is the local "elapsed" (Global is arg1) parameter that we're passing to our function. This is a variable that's being inherited from the WoW system telling us how long it's been since the last update call cycle.

; your_lua_file.lua
 -- Globals Section
 MyAddon_UpdateInterval = 1.0; -- How often the OnUpdate code will run (in seconds)
 
 -- Functions Section
 function MyAddon_OnUpdate(self, elapsed)
   self.TimeSinceLastUpdate = self.TimeSinceLastUpdate + elapsed; 	
 
   if (self.TimeSinceLastUpdate > MyAddon_UpdateInterval) then
     --
     -- Insert your OnUpdate code here
     --
 
     self.TimeSinceLastUpdate = 0;
   end
 end
Insert your code at the '-- Insert your OnUpdate code here', and substitute the ''MyAddon_'' with your addon's name. You might also want to tweak your ''MyAddon_UpdateInterval'' global variable to reflect how often your addon needs the code run; the less the better.  This solution also happens to be thread-safe, which is another issue when your code is being run every 0.1 seconds, finished or not.

If you're doing things that require high accuracy in the frequency of the OnUpdate calls, the above code won't be accurate since every time it is called, you will lose milliseconds as the ''TimeSinceLastUpdate'' variable is reset to 0 (If it was 1.05 seconds since last update, it would take 0.05 more seconds until the next update than it should, assuming that one hits 1.0, otherwise it would be delayed by another 0.05, etc). The below code accounts for this, and has a ''while'' structure to make sure that if the players framerate is very low, it'll still do the updates as many times as is needed.
 function MyAddon_OnUpdate(self, elapsed)
   self.TimeSinceLastUpdate = self.TimeSinceLastUpdate + elapsed; 	
 
   while (self.TimeSinceLastUpdate > MyAddon_UpdateInterval) do
     --
     -- Insert your OnUpdate code here
     --
 
     self.TimeSinceLastUpdate = self.TimeSinceLastUpdate - MyAddon_UpdateInterval;
   end
 end
[[Category:HOWTOs|Use OnUpdate Correctly]]