*SOLVED*class problem.

[TheBreadCat]

Code: Select all

function class()
    local cls = {}
    cls.__index = cls
    return setmetatable(cls, {__call = function (c, ...)
        instance = setmetatable({}, cls)
        if cls.__init then
            cls.__init(instance, ...)
        end
        return instance
    end})
end

i have this class function that makes a class decoration.

Code: Select all

player = class()


function player:__init()
	self.x = 320
	self.y = 240
	self.hspeed = 0
	self.vspeed = 0
	self.hp = 0
end

function player:update()
	self.x = self.x + self.hspeed
	self.y = self.y + self.vspeed
	self.vspeed = 0
	self.hspeed = 0
end


p = player()


function love.update(dt)
   p.update()
end

every thing should be fine, but im getting an error:
cant call field update(a nil value)

[BlackBulletIV]

I'm not quite sure where the error is coming from (I'm not all that familiar with the metatable, etc. stuff). However I can see one thing that's wrong:

Code: Select all

p:update() -- instead of p.update()

[leiradel]

Running you code with 0.7.0 gives me the following error:

Code: Select all

Error: [string "main.lua"]:24: attempt to index local 'self' (a nil value)
stack traceback:
        [string "main.lua"]:24: in function 'update'
        [string "main.lua"]:33: in function 'update'
        [string "boot.lua"]:314: in function <[string "boot.lua"]:302>
        [C]: in function 'xpcall'

BlackBulletIV's suggestion fixes it and a black screen is rendered.

Are you using 0.7.0?

Here's my main.lua with your code:

Code: Select all

function class()
    local cls = {}
    cls.__index = cls
    return setmetatable(cls, {__call = function (c, ...)
        instance = setmetatable({}, cls)
        if cls.__init then
            cls.__init(instance, ...)
        end
        return instance
    end})
end

player = class()

function player:__init()
   self.x = 320
   self.y = 240
   self.hspeed = 0
   self.vspeed = 0
   self.hp = 0
end

function player:update()
   self.x = self.x + self.hspeed
   self.y = self.y + self.vspeed
   self.vspeed = 0
   self.hspeed = 0
end

p = player()

function love.update(dt)
   p.update()
end

[SirLoon]

BlackBullet is right

[TheBreadCat]

Are you using 0.7.0?

yes, what are you running?

[TheBreadCat]

Running you code with 0.7.0 gives me the following error:

Code: Select all

Error: [string "main.lua"]:24: attempt to index local 'self' (a nil value)
stack traceback:
        [string "main.lua"]:24: in function 'update'
        [string "main.lua"]:33: in function 'update'
        [string "boot.lua"]:314: in function <[string "boot.lua"]:302>
        [C]: in function 'xpcall'

BlackBulletIV's suggestion fixes it and a black screen is rendered.

Are you using 0.7.0?

Here's my main.lua with your code:

Code: Select all

function class()
    local cls = {}
    cls.__index = cls
    return setmetatable(cls, {__call = function (c, ...)
        instance = setmetatable({}, cls)
        if cls.__init then
            cls.__init(instance, ...)
        end
        return instance
    end})
end

player = class()

function player:__init()
   self.x = 320
   self.y = 240
   self.hspeed = 0
   self.vspeed = 0
   self.hp = 0
end

function player:update()
   self.x = self.x + self.hspeed
   self.y = self.y + self.vspeed
   self.vspeed = 0
   self.hspeed = 0
end

p = player()

function love.update(dt)
   p.update()
end

still does not work just gets this:

Code: Select all

attempt to perform arithmetic on field 'x'(a nil value)

[vrld]

Code: Select all

attempt to perform arithmetic on field 'x'(a nil value)

Please look at the first reply again:

Code: Select all

p:update() -- instead of p.update()

[leiradel]

Are you using 0.7.0?

yes, what are you running?

0.7.0 on Windows, tested on both XP 32 bits and 7 64 bits. It runs fine on both, as long as you change p.update() to p:update().

[TheBreadCat]

Are you using 0.7.0?

yes, what are you running?

0.7.0 on Windows, tested on both XP 32 bits and 7 64 bits. It runs fine on both, as long as you change p.update() to p:update().

no it dont , i changed it.
do i also have to do it with variables?

[leiradel]

Ok, here's the code that I'm running without errors:

Code: Select all

function class()
  local cls = {}
  cls.__index = cls
  return setmetatable(cls, {__call = function (c, ...)
    instance = setmetatable({}, cls)
    if cls.__init then
      cls.__init(instance, ...)
    end
    return instance
  end})
end

player = class()

function player:__init()
  self.x = 320
  self.y = 240
  self.hspeed = 0
  self.vspeed = 0
  self.hp = 0
end

function player:update()
  self.x = self.x + self.hspeed
  self.y = self.y + self.vspeed
  self.vspeed = 0
  self.hspeed = 0
end

p = player()

function love.update(dt)
  p:update()
end

I've created a test folder in the same folder where love.exe lives, and put the above code in a main.lua file inside test. I'm then able to run it fine by either dragging test over love.exe or via the command line: love test.