- Joined
- Dec 12, 2010
- Messages
- 2,074
That's a guide for mid-level of JASSing, yet even profis don't really understand nulling.
Pretty much everyone knows about jass' thing "a leak". Basically, it's a link to an object you don't need to use anymore. Let's say you had to set location for creeps to go into. You gonna do it like that:
Why do you remove location here? 'Cause you don't need it anymore, you used it once and won't anymore. So you call it's destroyer object RemoveLocation and null the variable.
Let's take different example where you want to register every unit entering specific region
That's default Blizzard's function, and even tho it looks leaky, it's not dangerous at all. Created region will be used constantly, it's the thing which has trigger attached to. If you destroy region, trigger will be gone too. You don't need to null it either, since no matter what, region will stay there whole game, and you don't need to utilize it anyhow.
See the difference?
Leak's definition
Common description of leak is either not nulling, either not destroying of an object you won't use anymore. Thing is, nulling isn't big deal at all.
Whenever you assign an object (handle) to variable, it's inner counter increased by 1. Everytime you null object counter reduced by 1. This counter is used only for inner game's functions. It doesn't prevent game from destroying object if user said so - it rather blocks specific handle ID from recycling. Not a big deal, huh?
That means everytime you not null object which is destroyed, you waste 4 bytes of memory. Game won't re-use those, so will take following 4 bytes. So, in order to waste just 1 MB of RAM you have to make 1048576 leaks (1mln+).
Meanwhile object ARE heavy. They have very spreaded stats, like unit could take few KB with all his structures and inner links, while effect takes only few tens of bytes plus very few sub-calls. So, you actually need to remove objects, not the links. Don't starve for nulling everything, better watch out for things you leftover non-destroyed.
You have, let's say, an ability on the hero. On usage you use triggers to handle, and of course you put GetTriggerUnit() into variable for easier access. If you're sure hero won't be removed from the game, you don't need to null him at all. Same goes for destructibles you're not gonna delete, triggers you're not gonna remove, etc etc.
But can it lead to handle overload?
Well, definitely can. In theory. If you're using save games, probably. Because handles are counted with a 4 bytes unsigned counter, which means, at worst case, you may have up to 2^31 entities max, or 2 147 483 647. Seems enough for a few months of gameplay, isnt it?
Also I find HandleID lock very useful for some.. situatoins. This way you don't need to save 0's or nulls in the hashtables, using HandleID, to make sure there's no invalid data. You don't need to clean those either, in fact, but that's definitely not recommended technique.
Pretty much everyone knows about jass' thing "a leak". Basically, it's a link to an object you don't need to use anymore. Let's say you had to set location for creeps to go into. You gonna do it like that:
JASS:
local location l = Location(x,y)
if IsLocationVisibleToPlayer(l,GetTriggerPlayer()) then
call IssuePointOrderByIdLoc(GetTriggerUnit(),851297,l)
call RemoveLocation(l)
set l=nullLet's take different example where you want to register every unit entering specific region
JASS:
function TriggerRegisterEnterRectSimple takes trigger trig, rect r returns event
local region rectRegion = CreateRegion()
call RegionAddRect(rectRegion, r)
return TriggerRegisterEnterRegion(trig, rectRegion, null)
endfunctionSee the difference?
Leak's definition
Common description of leak is either not nulling, either not destroying of an object you won't use anymore. Thing is, nulling isn't big deal at all.
Whenever you assign an object (handle) to variable, it's inner counter increased by 1. Everytime you null object counter reduced by 1. This counter is used only for inner game's functions. It doesn't prevent game from destroying object if user said so - it rather blocks specific handle ID from recycling. Not a big deal, huh?
That means everytime you not null object which is destroyed, you waste 4 bytes of memory. Game won't re-use those, so will take following 4 bytes. So, in order to waste just 1 MB of RAM you have to make 1048576 leaks (1mln+).
Meanwhile object ARE heavy. They have very spreaded stats, like unit could take few KB with all his structures and inner links, while effect takes only few tens of bytes plus very few sub-calls. So, you actually need to remove objects, not the links. Don't starve for nulling everything, better watch out for things you leftover non-destroyed.
You have, let's say, an ability on the hero. On usage you use triggers to handle, and of course you put GetTriggerUnit() into variable for easier access. If you're sure hero won't be removed from the game, you don't need to null him at all. Same goes for destructibles you're not gonna delete, triggers you're not gonna remove, etc etc.
But can it lead to handle overload?
Well, definitely can. In theory. If you're using save games, probably. Because handles are counted with a 4 bytes unsigned counter, which means, at worst case, you may have up to 2^31 entities max, or 2 147 483 647. Seems enough for a few months of gameplay, isnt it?
Also I find HandleID lock very useful for some.. situatoins. This way you don't need to save 0's or nulls in the hashtables, using HandleID, to make sure there's no invalid data. You don't need to clean those either, in fact, but that's definitely not recommended technique.
