Access Hidden Tables

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-- Access inside table over __call

-- This is a very nice access since it only can be called over <this>()

function newT()

	-- create access to a table

	local _t = {}

	-- metatable

	local mt = {}

	mt.__call = function()

		-- hold access to the table over function call

		return _t

	end

	return setmetatable( {},mt )

end



-- Access inside table over commonly used variable self[self], inside __index

function newT2()

	local t = {}

	local mt = {}

	mt.__index = {

		[t] = {}

		}

	return setmetatable( t,mt )

end



-- Access inside table over nomal variable

-- disadvantage is that setting a key to _t will override

-- the access to the hidden table

function newT3()

	local mt = {}

	mt.__index = {

		_t = {}

		}

	return setmetatable( {},mt )

end



-- Access over nomal variable inside table

function newT4()

	local t = {}

	t._t = {}

	return t

end

-- CHILLCODE™

t = newT()

t1 = os.clock()

for i = 1, 1000000 do

	-- set var 

	t()[i] = i

	--access var

	assert( t()[i] == i )

end

print("TIME1:",os.clock()-t1)



t = newT2()

t1 = os.clock()

for i = 1, 1000000 do

	-- set var 

	t[t][i] = i

	--access var

	assert( t[t][i] == i )

end

print("TIME2:",os.clock()-t1)



t = newT3()

t1 = os.clock()

for i = 1, 1000000 do

	-- set var 

	t._t[i] = i

	--access var

	assert( t._t[i] == i )

end

print("TIME3:",os.clock()-t1)



t = newT4()

t1 = os.clock()

for i = 1, 1000000 do

	-- set var 

	t._t[i] = i

	--access var

	assert( t._t[i] == i )

end

print("TIME4:",os.clock()-t1)

TIME1:  0.67200000000003

TIME2:  0.86000000000001

TIME3:  0.60900000000004

TIME4:  0.56200000000001

So the indexing over a hidden variable is the second fastest, where as one should avoid tables as index to call a variable, and in certain cases access over __call could be the most appropriate