Can I cram all of this into a table?

[KayleMaster]

English is not my native language so can you please expand on that? "every time closure is generated" what is a closure in this scenario? usernameBox ?

And I assume the functions which you are talking about are new,draw and init? Do you mean new ones are created when I create usernameBox for example?

[zorg]

I think raidho was referencing MasterLee's solution, the one that mentions closures.

[raidho36]

Every time the code that defines a function runs, new function is generated. So if you put such code in top level, it only runs once, creating one function instance. But inside another function it runs every time that function runs, creating new function instance every time. Same as with tables!

If a function uses locals that were defined out of it's scope (e.g. just before it), it's called a closure, and the external variables are called upvalues. The closure will remember its upvalues, even if they are no longer accessible or even stopped existing. And if closure changes their value in runtime, it will remember that too the next time you call it.

[KayleMaster]

Ah, you were referring to MasterLee's code, yeah, got it.

[MasterLee]

But keep in mind that tables take more memory amount then using upvalues. So when you use many variable and have less code you may save memory.

[raidho36]

No actually even very simple closures consume way more memory than tables.

Code: Select all

local array, memory

local ClassT, ClassC = { }, { }
ClassT.__index, ClassC.__index = ClassT, ClassC

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

function ClassT:print ( )
	print ( self.x, self.y )
end

function ClassC.new ( x, y )
	local self = setmetatable ( { }, ClassT )
	function self:print ( ) print ( x, y ) end
	return self
end

array = { }
collectgarbage ( )
memory = collectgarbage ( 'count' )
for i = 1, 2 ^ 10 do
	array[ i ] = ClassT.new ( math.random ( ), math.random ( ) )
end
print ( 'Table Class', collectgarbage ( 'count' ) - memory )

array = { }
collectgarbage ( )
memory = collectgarbage ( 'count' )
for i = 1, 2 ^ 10 do
	array[ i ] = ClassC.new ( math.random ( ), math.random ( ) )
end
print ( 'Closure Class', collectgarbage ( 'count' ) - memory )

Code: Select all

Table Class	91.7314453125
Closure Class	164.0078125

[MasterLee]

Code: Select all

local array, memory

local ClassT, ClassC = { }, { }
ClassT.__index, ClassC.__index = ClassT, ClassC

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

function ClassT:print ( )
	print ( self.x, self.y )
end

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

function makeClosure ( x, y )
	return function ( ) print ( x, y ) end
end

array = { }
collectgarbage ( )
memory = collectgarbage ( 'count' )
for i = 1, 2 ^ 10 do
	array[ i ] = ClassT.new ( math.random ( ), math.random ( ) )
end
print ( 'Table Class', collectgarbage ( 'count' ) - memory )

array = { }
collectgarbage ( )
memory = collectgarbage ( 'count' )
for i = 1, 2 ^ 10 do
	array[ i ] = ClassC.new ( math.random ( ), math.random ( ) )
end
print ( 'Closure Class', collectgarbage ( 'count' ) - memory )

array = { }
collectgarbage ( )
memory = collectgarbage ( 'count' )
for i = 1, 2 ^ 10 do
	array[ i ] = makeClosure ( math.random ( ), math.random ( ) )
end
print ( 'Closure', collectgarbage ( 'count' ) - memory )

Actually it comes very close

Code: Select all

Table Class	91.681640625
Closure Class	164.0078125
Closure	84.0078125

[raidho36]

But you didn't use the class it was supposed to go with. The argument was that you could use a closure instead of metamethod and save memory, which is not true: class instance with closure on it consumes more memory than class with extra variables and metatable.

[MasterLee]

Class instance with closure makes no sense at all. Use Classes or Closures. For the code the was in opening post it is an alternative.

[raidho36]

Ah, right! Fair enough!