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How do I avoid spawn() and wait() spam?

Asked by

NotInventedHere 158

7 years ago

Edited 7 years ago

I have a function to decrease the range of a PointLight over time.

01spawn(function()
02 
03        local counter = 0
04 
05        while counter < 10 do
06 
07            pl.Range = pl.Range * (1 - counter / 10)
08            counter = counter + 1
09            wait()          
10 
11        end    
12 
13    end)

Is there a way to do this without having to use wait() and spawning a new function?

edit: I used spawn() as this function will run concurrently to many others in my game. Otherwise the scripts would pause just to wait for the light to be deleted

1 answer

Answered by

Goulstem 8144

7 years ago

Edited 7 years ago

The Spawn function creates a new thread for the thread scheduler to execute - it is for processing multiple actions at once. If you absolutely need to do two actions at once, what you're doing is fine.

The only alternative I may suggest is using the coroutine functions built into the API. Ultimately, these will produce the same outcome. But, coroutines are more powerful.

They allow you to be able to retrieve data outside of the initially defined thread(will give example)
You cannot yield the thread the spawn function creates with the exception of internal yield functions (and wait).

In other words, it is:

1spawn(function() -- [FIRST NEW THREAD]
2    print("hold on mydude, gotta go get something")
3end)
4local externalData = "Bob";
5wait(10);
6spawn(function() -- [SECOND NEW THREAD]
7    print("alright i'm back, the guy's name was: "..externalData")
8end)

vs:

01local a = coroutine.create(function() -- [FIRST NEW THREAD]
02    print("hold on mydude, gotta go get something");
03    local externalData = coroutine.yield();
04    print("alright i'm back, the guy's name was: "..externalData);
05end)
06 
07local theInfoInTheOtherRoom = "Bob";
08 
09coroutine.resume(a); -- [PLAYING FIRST THREAD]
10wait(10);
11coroutine.resume(a,theInfoInTheOtherRoom); -- [STILL JUST THE FIRST THREAD]

See what I mean? It's one thread, rather than two threads.

Note that I know this situation doesn't seem relevant to yours, and that I am mainly providing an example as to why you might consider using coroutine functions rather than spawn

**The `coroutine.yield` function will stop the thread until `coroutine.resume` is called upon the thread, externally, and will return whatever arguments were passed with resume**

So, the coroutine equivalents to your code would be:

create/resume

1local count = coroutine.create(function()
2    local counter = 0
3    while counter < 10 do
4        pl.Range = pl.Range * (1 - counter / 10)
5        counter = counter + 1
6        wait()          
7    end    
8end)
9coroutine.resume(count);

wrap

1local count = coroutine.wrap(function()
2    local counter = 0
3    while counter < 10 do
4        pl.Range = pl.Range * (1 - counter / 10)
5        counter = counter + 1
6        wait()          
7    end    
8end)
9count();

Thanks. I do appreciate you explaining the difference between spawn and coroutines. NotInventedHere 158 — 7y

No problem :) Goulstem 8144 — 7y

How do I avoid spawn() and wait() spam?

1 answer

The coroutine.yield function will stop the thread until coroutine.resume is called upon the thread, externally, and will return whatever arguments were passed with resume

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**The `coroutine.yield` function will stop the thread until `coroutine.resume` is called upon the thread, externally, and will return whatever arguments were passed with resume**