[SOLVED] How Do I Directly Modify A Value Called With A Function?

I cant think of a good name for this question, apologies if this one is long winded or confusing.

I'm finally getting acquainted with OOP, for my current project I'm making a Vector pseudo-class.

Vector = setmetatable({}, {__call = function(_, x, y, z)
	x, y, z = x or 0, y or 0, z or 0
	return setmetatable({
		-- VALUES
		["x"] = x, 
		["y"] = y, 
		["z"] = z,
		-- METHODS
		["Add"] = function(augend, addend)
			-- code adding the Vectors
		end,
		}, {
		__add = function(augend, addend)
			-- code adding the Vectors
		end,
	})
end,__metatable = true})

return Vector

misc code removed for brevity

Here's the differences between how the two methods would work.

__add

local Vector = require(pseudoVector) -- requiring the above module

local originalVector = Vector(1, 1, 1)

local addendVector = Vector(0, 1, 0)

local newVector = originalVector + addendVector

print("newVector = " .. newVector)
print("originalVector = " .. originalVector)

newVector = 1, 2, 1 originalVector = 1, 1, 1

Add()

local Vector = require(pseudoVector) -- requiring the above module

local originalVector = Vector(1, 1, 1)

local addendVector = Vector(0, 1, 0)

local newVector = originalVector:Add(addendVector)

print("newVector = " .. newVector)
print("originalVector = " .. originalVector)

newVector = 1, 2, 1 originalVector = 1, 2, 1

The __add method adds addendVector to originalVector, puts the result into a new Vector, and returns it. Whereas the Add function adds addendVector directly to originalVector, changing its values.

I'm not too sure how that would work.

Like how would I directly modify the augend's values from a function, which to my knowledge creates a copy of the data instead of directly referencing it. Or how I would use my Metatable inside itself to create a new Vector instance to return.

#Any help would be appreciated.