CODEWITHSUNDEEP
lua
Louis Etienne
Louis Etienne

Reputation: 1371

Trying to access table value within the table

I'm trying to do this

local ball = {
        width = 20,
        height = 20,

        position = {
            x = (game.width / 2) - (width / 2), -- Place the ball at the center of the screen
            y = (game.height / 2) - (height / 2)
        },

        velocity = 200,
        color = { 255, 255, 255 }
    }

But Love2D say me attempt to perform arithmetic on global 'width' (a nil value). How can I fix it?
I already tried to replace width / 2 with ball.width / 2 but I got attempt to index global 'ball' (a nil value).

Upvotes: 1

Views: 63

Answers (1)

Nicol Bolas
Nicol Bolas

Reputation: 474436

Remember that local some_name = expression is equivalent to:

local some_name
some_name = expression

This allows some_name to appear in expression. In particular, it allows recursion with local functions. However, until expression is actually finished being evaluated, the value of some_name is still nil.

So within your table initialization, ball is a nil value. There is no way to access members of a table while that table is being initialized. You can however do so afterwards:

local ball = {
    width = 20,
    height = 20,


    velocity = 200,
    color = { 255, 255, 255 }
}

ball.position = {
    x = (game.width / 2) - (ball.width / 2), -- Place the ball at the center of the screen
    y = (game.height / 2) - (ball.height / 2)
}

Upvotes: 5

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