love.physics.newBody() error

[intensity]

What's wrong with this line? The compiler says "attempt to index field '?' (a nil value)".

blocks[a] = love.physics.newBody(world, 50 + (20 * a), 50 + (20 * b), 0, 0)

[leiradel]

blocks[a] = love.physics.newBody(world, 50 + (20 * a), 50 + (20 * b), 0, 0)

It could be that you've created the blocks table but not the blocks[a] tables. Example:

Code: Select all

blocks = {} -- create the first array dimension
for a = 1, 10 do
  blocks[ a ] = {} -- create the second array dimension for each a
  for b = 1, 10 do
    blocks[ a ][ b ] = love.physics.newBody(world, 50 + (20 * a), 50 + (20 * b), 0, 0)
  end
end

[intensity]

That's probably it. blocks[1][1] would screw up if blocks[1] had no value?

[leiradel]

blocks[1][1] would screw up if blocks[1] had no value?

Yes. Lua doesn't have multidimensional arrays, just arrays of arrays, i.e.

Code: Select all

blocks = {} -- blocks can be used as an array but blocks[1] has no value
blocks[1][1] = 1 -- errors, blocks[1] is nil
blocks[1] = {} -- now blocks[1] can also be used as an array
blocks[1][1] = 1 -- works

[zac352]

What's wrong with this line? The compiler says "attempt to index field '?' (a nil value)".

blocks[a] = love.physics.newBody(world, 50 + (20 * a), 50 + (20 * b), 0, 0)

Not a compiler. Interpreter.
HUGE DIFFERENCE.

[leiradel]

Not a compiler. Interpreter.

Actually Lua is both, the compiler translates source code into bytecode and the VM interprets the bytecode to carry on the operations defined in the source code.

[zac352]

Not a compiler. Interpreter.

Actually Lua is both, the compiler translates source code into bytecode and the VM interprets the bytecode to carry on the operations defined in the source code.

That's an interpreter. Note: I know that lua has a compilable file for making a lua compiler. so yeah.

[leiradel]

That's an interpreter.

Yeah, that's debatable. I was just pointing that Lua actually compiles things.