Troubles with Lua class and OOP

[Japple]

Hello guys, I'm kinda new to Lua and i have some previous experience with OOP in Java and C++. I've been playing with Love2d, i made a player class but i can't get it to work every time i load my game into love2d this error shows.



Here's my main.lua

Code: Select all

debug = true 
player = require 'Player'
p1 = player.new()


function love.load(arg)
	
end

function love.update(dt)
	p1.movement()
end

function love.draw(dt)

end

and here's player.lua

Code: Select all

Player = {}

function Player.new(x,y)
	local plyr setmetatable({}, Player)

	plyr.x = x
	plyr.y = y
	plyr.xspeed = 0
	plyr.yspeed = 0

	return plyr
end

function Player:movement()
	if love.keyboard.isDown('a') then
		print ("love")
	end
end

Please bear with me i'm retarded .

[Nixola]

You're supposed to return Player at the end of player.lua.

[Japple]

You're supposed to return Player at the end of player.lua.

I think i found another way to do it

main

Code: Select all

debug = true 
require 'player'
player = Player.new(1,2)
print (player.x)


function love.load(arg)
	
end

function love.update(dt)

end

function love.draw(dt)

end

player

Code: Select all

Player = {}
Player.__index = Player

function Player.new(x,y)
	local self = setmetatable({}, Player)
	self.x = x
	self.y = y
	return self
end

After hours of searching it works! I'm not quite sure what metatables are use for tho

[zorg]

It works because you defined Player as a global in player.lua

You generally don't want to do that since it pollutes the scope.

You do local Player = {}
and then
return Player
at the end.

[Japple]

It works because you defined Player as a global in player.lua

You generally don't want to do that since it pollutes the scope.

You do local Player = {}
and then
return Player
at the end.

I'm still gettin an error

Code: Select all

debug = true 
require 'player'
player = Player.new(1,2)
print (player.x)


function love.load(arg)
   
end

function love.update(dt)

end

Code: Select all

local Player = {}
Player.__index = Player

function Player.new(x,y)
   local self = setmetatable({}, Player)
   self.x = x
   self.y = y
   return self
end

return Player

if someone give me an example of how should be done i would really appreciate it

[airstruck]

You're getting that error because there's no longer a Player variable visible at the point where you reference it. When you call require, it returns whatever your module returned (more or less; please read the manual for the exact details). You need to store that value in a local variable.

http://lua-users.org/wiki/ModulesTutorial

[Roland_Yonaba]

I'm still gettin an error
if someone give me an example of how should be done i would really appreciate it

Hi Japple,

The way you have defined you code in Player.lua is quite fine. You defined it in a way it is self-contained within the scope of the file itself, which is a very good practive you should keep doing when writing Lua code.
But you are getting an error because of the way you are using it inside main.lua.
See, when you require the file Player, it returns something (because of the return statement at the end of thi very file). But obviously, if you wan to use what this file returns (the module Player), then you need to assign it to some variable to get a proper reference to it.

So something like:

Code: Select all

-- Catch what is returned by the file player.lua 
-- and assign it to a local variable named Player withing the file main.lua

local Player = require 'player' 
-- and then use it as you wish
player = Player.new(1,2)
 -- etc etc
 

[zorg]

Also, as you can see, the name of the table inside your "class" (i.e. other file(s)), the name of that file, and the name of the variable you'll require it into can all differ, though it's a good thing to be consistent in these matters.

[Japple]

Thanks you all guys it works