Quick question on leaks on global points

[Inflicted]

This is just a quick thought,

in a GUI trigger. Using a global Location/Point variable, it would normally have to be reset/nulled at the end. (obviously before waits/Triggersleeps)

if one was to declare it, and then re-use that same variable, would it have to be nulled twice? or only at the end?

Eg. I have to spawn 2 units at a point set at random.

Point variable is set to random location
First unit is created at variable position
[]
Point variable is set to a different random location
Second unit is created at variable position
Point variable is nulled.

Where the [] is, does the variable need to be nulled again before used? Is memory lost or anything? Or is it acceptable just to null it at the end? (Reducing lines of code and saving time)

This would perhaps help in the case of a loop:

eg.
Loop For 1-100:
{
Set point = Random Point
Create unit at variable location
[null variable?]
}
null location variable

In this case is the "[null variable?]" neccessary? - I'm sure it would benefit if that was nulled only at the end. Note this is the usage of one variable over-written.
Bad idea or good time/memory saver?

 

[skyblader]

Bad idea. If you don't clear the first position before using it for another, the memory of the first location is not removed and lost somewhere in the game.. Therefore it leaks. You gotta destroy them after use or before its next use, and then again after that.

 

[Darthfett]

In general, you only need to null local variable values (which are not really possible to use in the GUI). Globals tend to get re-used anyways.

You do need to worry about removing the leak from each of those points. If you have a variable called 'Point', you need to use this Custom Script: [ljass]call RemoveLocation(udg_Point)[/ljass]

One thing to keep in mind about global variables (the variables you use in GUI), is that they can get overwritten after a Wait, so you ought to destroy them before the wait, as you said.

You can find more information about this in a leak tutorial, but the purpose of nulling variables is so that there are no longer any variables pointing to its value. The internal garbage collection cannot remove memory until no more pointers remain.

 

[GFreak45]

wrong sky, you clear them at the end of the trigger
if the trigger goes to completion without clearing the variable it then causes a leak
it makes more sense when you learn jass
and if you try to clear anything in a loop its: [ljass]call RemoveLocation(udg_VariableName[bj_forLoopAIndex])[/ljass]

 

[skyblader]

So if we set it to 4 locations and clear it at the end of the trigger, it doesn't leak? My bad then. ><

 

[Darthfett]

So if we set it to 4 locations and clear it at the end of the trigger, it doesn't leak? My bad then. ><

If you are using an Array, and using different points, then you can use the snippet GFreak45 posted inside a loop to remove the leaks in the array. The OP didn't specify that he was using an array, however, and so I did not mention the method for this. He seemed to be generating a new point each time, and didn't need the points to be pre-generated.

 

[KaerfNomekop]

If the four points are different, then you have to clear each one. If you use the same point without changing it throughout the trigger, then you only clear it once. Each time you set the variable to refer to a new point, you should clear it before you set it again.

 

[skyblader]

If the four points are different, then you have to clear each one. If you use the same point without changing it throughout the trigger, then you only clear it once. Each time you set the variable to refer to a new point, you should clear it before you set it again.

But that's what I meant. If the same variable is used again, it leaks right? For example:

Set PosVar = Position of Unit 1
Set PosVar = Position of Unit 2
call RemoveLocation(udg_PosVar)

It leaks right?

 

[Inflicted]

Okay I understand. Thank you, better change a few of my triggers then

I believe that then, in the above example it would leak. Needing to null before the second setting of the variable.

Ty.

 

[KaerfNomekop]

It would leak, because "Position of Unit 1" has been referenced, but you can't reference it again later. Therefore the leak must be cleared before setting to "Position of Unit 2".

 

[Darthfett]

Okay I understand. Thank you, better change a few of my triggers then

I believe that then, in the above example it would leak. Needing to null before the second setting of the variable.

Ty.

You do NOT need to null. Only in JASS do you have to worry about doing this, unless you are NEVER going to use PosVar again.

 

[KaerfNomekop]

Nulling is used only for locals, right?

 

[Darthfett]

Nulling is used only for locals, right?

Or, if you're extremely paranoid or have a hundred million globals that you don't plan on using again, you might null those too. But in general, yes, only for locals.

 

[Inflicted]

oh.

ty again.