Function as argument

[MobinYengejehi]

hi guys
i could made a method that help lua to pass a function as argument and send it to other resources
and you can use it in both server and client sides
you can pass function as argument in triggerEvent or exports.resource:func_name or setElementData(if you set 4th argument to false) and send it to another resource and call it
and also you can send functions in table (but you can't share metamethods)
for example:

-- resource : A
local player = nil;

local library = {};

function library.SetPlayer(element)
    if isElement(element) then
        player = element;
    end
end

function library.GetPlayer()
    return player;
end

addEvent("getlibrary", false);
addEventHandler("getlibrary", localPlayer, function(send)
    iprint("function is:", send, type(send)); -- type(send) = table
    send(library);
    print("library sent to ", getResourceName(send.resource));
    send:free(); -- cleanup function reference at resource B (this cleans up the memory. if you don't call this method it stays in memory untill program destroy lua stack like stopping resource)
end);

-- resource : B
local library;

triggerEvent("getlibrary", getLocalPlayer(), function(resourceALibrary)
    library = resourceALibrary;
    print("resource B got the library!");
end);

if library then
    print("player is : ", library.GetPlayer()); -- nil
    library.SetPlayer(getLocalPlayer());
    print("player is : ", library.GetPlayer()); -- local player
end

when you pass a function as an argument it will look like a table
and has these values:
-- function reference:
.resource : the resource that owns function
.reference : the reference id
.free : this method deletes the reference. if you call it, means that you won't be able to use that function anymore

note 1 : you can store a function reference in other resource if you want to let it be active otherwise if you call that function in render event or sth like that and you don't use :free method, after seconds your game or server console crashs because it occupies your memory
note 2 : remember when you want to cleanup your function call it as method, like function:free (not like function.free) because free needs a callable value as first argument

[CrosRoad95]

couldn't you just implicit convert functions to refs using ref and deref

[MobinYengejehi]

couldn't you just implicit convert functions to refs using ref and deref

i think i couldn't understand well what you mean
but if you mean why those are table
its because it doesn't cause confusion when passing a function as an argument in triggerEvent and other functions and you can check in other resources that where does this function come from

[salwador]

No news about this PR? I can't imagine a cases for what need store functions in elementData, but for exports it very useful. 🤔

[Fernando-A-Rocha]

This reminds me of #3551

[tederis]

When a referenced resource become stopped this pointer will turn into the dangling one. From what I was able to see there is no an invalidation mechanism for functions.

[MobinYengejehi]

i agree

[MobinYengejehi]

i have some cleaner and better version in my mind for this
i will work on it and update its PR to use that instead

[tederis]

I consider this feature as excessive and the implementation as dangerous.

[MobinYengejehi]

i need time to refactor this PR

[MegadreamsBE]

I'm opposed to this. There's no good reason for this to exist, it can be dangerous AND it can cause easy memory leaks.