4 replies to this topic

[carmellose]

hi guys,

i'm begining LUA with (luabind for c++ bindings) and it seems i didn't understood something, because when i try to declare a class with tables inside, i have a strange error.

basically, i have a class declared like:

class 'scheduler'
--
function scheduler:__init(agents)
	print("[+] new scheduler instance ...")
	self.agentsCoroutines = {}
	self.writesQueue = {}
	for i,j in pairs(agents) do
	table.insert(self.agentsCoroutines, {
										coroutine.create(agents[i][1]), 
										agents[i][2] --[[channel--]]} )
	print(self.agentsCoroutines[i],"status:",coroutine.status(self.agentsCoroutines[i][1]) )
	end
	return self
end

this works, albeit when i declare this:

function scheduler.start()
	local myThread = self.agentsCoroutines
end

i have this strange error:

Quote:

attempt to index global 'self' (a nil value)

do you know what i'm having wrong??

thank you in advance

[Giedrius]

function scheduler.start() should be function scheduler:start(), with a : instead of a .

[carmellose]

Quote:

Original post by Giedrius function scheduler.start() should be function scheduler:start(), with a : instead of a .

hi
i've tryed it but i still have the same problem :/

[carmellose]

up

[ddn3]

post your class definition for the scheduler, it should be something like this:

scheduler = { } -- Create a table to hold the class methods
 function scheduler:new() -- The constructor
   local object = {
	mMemebers=nil,
   }
   setmetatable(object, {
     -- Overload the index event so that fields not present within the object are
     -- looked up in the prototype parent class table
     __index	= scheduler
   })
	return object
 end

function scheduler:start()
	local myThread = self.agentsCoroutines
end

The idea of programming OO in Lua is to create a instance of a table with the approraite __index methamethod to allow access to the methods of that class.

You create the scheduler instance using some function similar to the :new() from above. Like so :

local instance = scheduler:new();

now the self parameter is valid for the given instance, otherwise calling the function of scheduler will not have any valid self parameter, whether u use the : or . notation.

now you can do something like..

instance:start();

There isn't enough information from the scheduler class to give you any clear answers.

Good Luck!

-ddn