(Solved) HUMP Class - attempt to index local '***' (a nil value)

[Bigfoot71]

Hello everyone !

So I find myself facing a problem that I can't explain to myself, I started using HUMP to do my Classes and I get an error that I can't understand...

Here is the file that contains the class in question:

Code: Select all

Player = Class {

    init = function(self, img, pos)

        self.img = img
        self.pos = pos

        self.w, self.h = img:getDimensions()
        self.ox, self.oy = self.w / 2, self.h / 2

    end;

    draw = function(self)
        lg.draw(
            self.img,
            self.pos.x,
            self.pos.y,
            nil,
            nil,
            nil,
            self.ox,
            self.oy
        )
    end;

}

return Player

For line self.w, self.h = img:getDimensions() I get:

Code: Select all

Player.lua:8: attempt to index local 'img' (a nil value)

whereas img is indeed passed as a parameter because without that my image is displayed.

I "instantiate" it like this in another file:

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local path = ...

local Player = require(path.."/Player")

local player = Player()

local player_tex = lg.newImage(
    "assets/images/player.png"
)

-- State definition --

local game = {}

function game:enter()
    player:init(player_tex, Vec(display.size.w/2, display.size.h/2))
end

function game:update(dt)
    --player:update(dt)
end

function game:draw()
    player:draw()
end

return game

I also tried to define the "methods" outside the table as a parameter of Class but the result is exactly the same...

EDIT: I temporarily solved the problem by doing:

Code: Select all

if img ~= nil then
    self.w, self.h = img:getDimensions()
    self.ox, self.oy = self.w / 2, self.h / 2
end

But it's not very clean or very practical and I would like to know if you have a better solution

Thanks in advance !

[SelfDotX]

I could be wrong (im new too) but I don't think you call init directly. If I had to guess it should look like:

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local player = Player(img, pos)

or

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local player = Player.new(img, pos)

Just a guess

[ReFreezed]

SelfDotX is correct. Class libraries, including the one in HUMP, tend to support an 'init' method that gets called automatically when the object is first created (i.e. by the Player() call here).

[Bigfoot71]

I removed local player = Player() and changed player:init(x, x) to player = Player(x, x) but I always have the same error when I want to retrieve the dimensions of img (like what the parameter img would be nil whereas without the img:getDimensions() the image is displayed fine)

[ReFreezed]

Did you maybe misspell the image variable? The fixed code should be something like this:

Code: Select all

local player
local player_tex = lg.newImage("assets/images/player.png")
function game:enter()
    player = Player(player_tex, Vec(display.size.w/2, display.size.h/2))
end

[Bigfoot71]

Oh yes my apologies, I went too fast, I had forgotten a letter while rewriting, thank you very much !