How do you hook in to functions?

Ironsoul

Hello again, here I am seeking aid from people more knowledgable in the arts of coding than I.

This day, I'm trying to add some functionality to an existing function in the ns2 code. Specifically the ResourcePoint:Reset() function. Here's the code I tried:

Script.Load("lua/ResourcePoint.lua")

do
    local oldResourcePointReset = ResourcePoint:Reset()
    ResourcePoint:Reset = function()
        oldResourcePointReset()
        Print("Resource Point detected")
        //attempted hook in
    end
end

Obviously, this isn't working, meaning I've done something wrong.

It would be fantastic if someone would explain to me what I've done wrong, and optionally why what I tried was wrong.

All the best,

Ironsoul.

SamusDroid

I'd like to know how to do this too!

fsfod

Ironsoul wrote: »

Hello again, here I am seeking aid from people more knowledgable in the arts of coding than I.

This day, I'm trying to add some functionality to an existing function in the ns2 code. Specifically the ResourcePoint:Reset() function. Here's the code I tried:

Script.Load("lua/ResourcePoint.lua")

do
    local oldResourcePointReset = ResourcePoint:Reset()
    ResourcePoint:Reset = function()
        oldResourcePointReset()
        Print("Resource Point detected")
        //attempted hook in
    end
end

Obviously, this isn't working, meaning I've done something wrong.

It would be fantastic if someone would explain to me what I've done wrong, and optionally why what I tried was wrong.

All the best,

Ironsoul.

Youre mixing up the self call syntax ":" with the normal "." style access

local oldResourcePointReset = ResourcePoint:Reset() 

should be

local oldResourcePointReset = ResourcePoint.Reset

and you need to capture and pass the self parameter to the original function since you're not defining the function with self call syntax which implicitly includes the self parameter

ResourcePoint.Reset = function(self)
        oldResourcePointReset(self)

Ironsoul

Worked great, thanks @fsfod. No longer do i need to rip apart existing lua files.

MCMLXXXIV

That way looks great and will work - if you're looking for an alternative here is the simplest example I can find from our new Combat/Xenoswarm codebase. I prefer a syntax which allows me to use the same syntax for the function definition as is used in the vanilla codebase

In this example we hook into the Create function to add a new mixin to grenade launchers. We can also add new networkVars into the networkVars table at the top, and they will get added to the class:

local networkVars = {
}

AddMixinNetworkVars(ClipSizeMixin, networkVars)

local overrideOnCreate = GrenadeLauncher.OnCreate
function GrenadeLauncher:OnCreate()

	overrideOnCreate(self)
	
	local clipSizeParameters = { kBaseClipSize = kGrenadeLauncherClipSize,
								 kClipSizeIncrease = 1, }
	InitMixin(self, ClipSizeMixin, clipSizeParameters)
	assert(HasMixin(self, "VariableClipSize"))	
	
end

Class_Reload("GrenadeLauncher", networkVars)

Ironsoul

I didn't really understand that much @MCMLCXXXIV but in time I probably will. Thanks for giving me another path to explore later.