LÖVE

Posted: **Sun Nov 11, 2012 8:59 pm**

Hello World

I'd like to create simply Object creator with for loop:

for i=1,10 do

object.x=100
object.y=100
object.body=love.physics.newBody(world, object.x, object.y "dynamic")
object.shape=love.physics.newRectangleShape(21,21)
object.fixture=love.physics.newFixture(object.obj.body, object.obj.shape, 1)

end

But I got:

Attempt to index field "?" (a nil value)

So what's going on?

I came back to LUA and it's seems I forgot a little bit

Posted: **Sun Nov 11, 2012 9:00 pm**

The table "object" has to been created before puttings something into it.

[edit deleted: does not work like this because of the physic things.]

Posted: **Sun Nov 11, 2012 9:15 pm**

Yea, I created it earlier, just didn't posted it.

object={}

And problem is still ariving

#EDIT

Eh, stupid me >_<

In loop, you must make table in table, which is:

object={}

for i=1,10 do
object={}
object.x=100
object.y=100
object.body=love.physics.newBody(world, object.x, object.y, "dynamic")
object.shape=love.physics.newRectangleShape(21,21)
object.fixture=love.physics.newFixture(object.body, object.shape, 1)

end

Posted: **Mon Nov 12, 2012 12:22 pm**

Krizzu wrote:Hello World

I'd like to create simply Object creator with for loop:

for i=1,10 do

object.x=100
object.y=100
object.body=love.physics.newBody(world, object.x, object.y "dynamic")
object.shape=love.physics.newRectangleShape(21,21)
object.fixture=love.physics.newFixture(object.obj.body, object.obj.shape, 1)

end

But I got:

Attempt to index field "?" (a nil value)

So what's going on?

I came back to LUA and it's seems I forgot a little bit

A function that creates tables (data structures) is usually called constructor or factory. What you want to do is probably something like this:

Code: Select all

make_objects = function ()
   local objectS = {}

   for i=1,10 do
      -- create new object
      local obj = {}
      -- describe its contents
      obj   = {}
      obj.x = 100
      obj.y = 100
      obj.body    = love.physics.newBody(world, obj.x, obj.y, "dynamic")
      obj.shape   = love.physics.newRectangleShape(21,21)
      obj.fixture = love.physics.newFixture(obj.body, obj.shape, 1)
      -- define it as item #i in objectS
      objectS[i] = obj
   end
   
   return objectS
end

Note: you should always call a table that represents a set of items (a collection) with a plural 's'. Unless there is an obvious name such as 'colony' for a set of ants or 'palette' for a set of colours (or 'staff' for a set of employees). Also, it is a good idea --to avoid mistakes or typos-- to use a shortcut name for items, in a loop that processes items in a row (as I did with 'obj' above).

Denis

OT: Seems the forum does not permit all of BBCode? (I tried to use [s] for srike-through). See http://en.wikipedia.org/wiki/BBCode

Posted: **Mon Nov 12, 2012 7:49 pm**

Code: Select all

t = {}

for x=1, 10 do
     t[x] = {}
     t[x].property = "value"
end

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