Love2d adding value to table inside for loop.. Using a variable

Question

This is something that's really been nagging at me for some time:

for i = 1, 4 do
   x = love.physics.newFixture(diffTable[i].body, diffTable[i].shape):setCategory(10)
   x = x:setUserData('Border') -- error here
   table.insert(data, x)
end

Let's say I want to insert a variable into the table (basically creating the variable, and then modifying it) and then inserting it:

When I do the x = x:setUserData(...) an error comes up.. saying attempt to index global variable x (nil)

So my question is, how would I create a variable inside a for loop, specifically I need to do it this way because I'm using love.physics, and creating a fixture with a category. I also need to setUserData at that time but it's not possible.

And I'm sure there has to be a way of doing this... Thanks in advance!!

Can you specify what your expected and actual outcome is? Like, do you want data.x to be the same value as x? Or do you want data[1] = { x = x, y = y } (that's what your first line with table.insert would do)? — Henrik Ilgen
– Henrik Ilgen, Commented Mar 22, 2021 at 9:48
your code doesn't make any sense. what do you want to achieve? improve your post. the provided code is full of errors and it does not help to show whwat you want to do. improve it — Piglet
– Piglet, Commented Mar 22, 2021 at 14:09
@codeRdevelopR if you expect that result then you shouldn't be using table.insert. table.insert will put the value at the next numeric index available. lua.org/manual/5.3/manual.html#pdf-table.insert lua.org/pil/19.2.html — Nifim
– Nifim, Commented Mar 22, 2021 at 14:19
Yes I've changed the question slightly.. its more detailed :) — nodeDevcoder
– nodeDevcoder, Commented Mar 22, 2021 at 14:23

Nifim · Accepted Answer · 2021-03-22 14:43:47Z

3

The function Fixture:setCategory does not return a value.

so when you do this

x = love.physics.newFixture(diffTable[i].body, diffTable[i].shape):setCategory(10)

you are setting x = nil. Fixture:setUserData also does not return a value.

If you change it to this you will no longer get that error.

for i = 1, 4 do
   x = love.physics.newFixture(diffTable[i].body, diffTable[i].shape)
   x:setCategory(10)
   x:setUserData('Border') -- error here

   table.insert(data, x)
end

edited Mar 22, 2021 at 14:43

answered Mar 22, 2021 at 14:28

Nifim

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3 Comments

Nifim Over a year ago

Looked into setUserData just now it also does not return a value.

Piglet Over a year ago

@codeRdevelopR that's why you should always refer to manuals. programming is not some magic power. it basically boils down to reading documentations.

Nifim Over a year ago

This is very true, in fact, I really dont know anything about love2d I just looked up the function you were using to set the value of x in the love2d documentation, as the simplest answer to why x = nil is that the function returns nothing.

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