[vJASS] extended vs normal structs

[Starquizer]

So what makes struct sss extends array better than struct sss ?

Ok, I was trying to learn how Alloc module works but I found it is similar to the same overhead created in normal structs except for the Double free protection.

So why would I bother to make the struct extends array ?

 

[Troll-Brain]

If you're a speedfreak and/or a script size freak, go for struct extends array.

Really, the only time you would use a struct extends array, is when you don't need the default struct allocators (ofc also if you just want to use the struct api without any allocator)

 

[Starquizer]

If you're a speedfreak and/or a script size freak, go for struct extends array.

How do I test speed then ?

 

[PurplePoot]

extends array is for when you want a struct to just behave as a bunch of arrays (which is what it is) and not worry about allocating/deallocating it.

 

[Starquizer]

... just behave as a bunch of arrays (which is what it is) ....

bunch of arrays ? what do you mean by that ?

 

[PurplePoot]

bunch of arrays ? what do you mean by that ?

As if each member variable is just its own array.

Basically it means you access the struct by index, not by instance. It's as if you have a pre-made array of allocated structs which can't be destroyed.

 

[Starquizer]

As if each member variable is just its own array.

Basically it means you access the struct by index, not by instance. It's as if you have a pre-made array of allocated structs which can't be destroyed.

OK, but another thing, if I want to run a speed test on normal struct and array extended one, how can I do that ?

 

[PurgeandFire]

You have to stress test. But the speed difference behind that is mostly based on logic, because obviously a method that uses fewer calls/checks will perform faster.

However, it is not super necessary unless you are a speed freak. There are other uses for extending array, but usually you'll see it just used for more efficient allocation/deallocation.

If you are still learning vjass, in my opinion you don't have to really worry about it. You can just use normal structs.

 

[mckill2009]

Purge is right, the fewer the calls, or calculations, the faster that is, see the difference between Alloc and http://www.hiveworkshop.com/forums/jass-resources-412/snippet-linkedlistmodule-206552/ and you can see which is faster,if you wanna know more about other uses for extending structs, I suggest you read the JassHelper...

 

[Starquizer]

@ PurgeandFire111
I know that a fewer function call is faster but how do I make an fps speed test ?

 

[PurplePoot]

Short answer: just don't use it unless you absolutely need to, it's not worth it.

 

[PurgeandFire]

@ PurgeandFire111
I know that a fewer function call is faster but how do I make an fps speed test ?

You'll have to stress test it. You'll have an empty map where you run one code, and you have to loop it like tens of thousands of times. Then record the fps (type /fps in chat) and run the code and see how much it has dropped. Then close the map, change the code to run your other code, and then do the same process.

However, the results aren't conclusive unless the difference is significant. (like 10 or so fps) But even then, the only applies to extreme cases. Poot summed it up, you don't really have to worry about it. You won't notice the speed difference. Most system makers will only go out of their way for minor speed gains just to prevent critique on that end.

 

[Starquizer]

@ PurgeandFire111
Thanks, but one little thing how do I view the fps, is there some third party tool that I should run with WC3 or there is something I can do inside the game to view the fps ?

 

[Troll-Brain]

Just type "/fps" in game.

But anyway you have to know lot of things to make a good stress test, and it will tell you only which way is the faster, you can't really count on accuracy.
Note that the fps drop is not supposed to be linear, so for the two test codes you would have to get the same fps frop and compare how many operation you do in code A, and code B.
Plus in real codes, the struct allocation is clearly not the most expensive thing, while the api is uglier and error prone when you inline and use a custom struct allocator and struct extends array.
Hence the reason why struct extends array are useless in most of cases (at least when you need usual struct allocators)