CODEWITHSUNDEEP
ooplua
antwoord
antwoord

Reputation: 13

lua oop starting out

I'm trying to get some code working from this video: Lua Tutorial 9: OOP and Metatables about 11 minutes into the video

I'm new to lua but i have programming experience so after going through the basics of the language i'd thought i'd learn some ways to do oop. In my code i've replaced vector3 with Vector2 since i need to work in 2d for now. Lua's powerful tables is something that is something i really need to understand to be more fluent in the language of coarse .

however i get an error: input:38: attempt to perform arithmetic on a table value (local 'v1')

I have the same issue testing in: the lua demo interpreter The code i'm trying out:

Vector2 = {x = 0, y = 0}
Vector2.prototype = {x = 0, y = 0}
Vector2.mt = {}
Vector2.new = function()
    local vec = {}
    setmetatable(vec, Vector2, mt)
    for k, v in pairs(Vector2) do
        vec[k] = v
    end
    return vec
end

Vector2.mt.__add = function(v1, v2)
    local vec = Vector2.new()
    vec.x = v1.x + v2.x
    vec.y = v1.y + v2.y
    return vec
end

function draw()
    local v1 = Vector2.new()
    local v2 = Vector2.new()
    v1.x = 10
    v1.y = 34
    v2.x = 20
    v2.y = 22
    v1 = v1 + v2
    print(v1.x)
end


draw()

Any thoughts. Thanks.

Upvotes: 1

Views: 104

Answers (1)

Vlad
Vlad

Reputation: 5847

You've made a typo when copied text from the video.

The line setmetatable(vec, Vector2, mt) should be setmetatable(vec, Vector2.mt)

Upvotes: 1

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