Trivial n-tuple implementation. Tuples containing NaN are only equal to themselves (the exact same instance). Save it as 'tuple.lua'. For usage see MultipleKeyIndexing.

--[[
	(...) -> tuple
	wrap(t, [n]) -> tuple
]]
local setmetatable, select, table, tostring =
	 setmetatable, select, table, tostring
setfenv(1, {})
local meta = {__type = 'tuple'}
local function wrap(t, n)
	t.n = n or t.n or #t
	setmetatable(t, meta)
	return t
end
local function new(...)
	return wrap({n=select('#',...),...})
end
function meta:__eq(other)
	if self.n ~= other.n then
		return false
	end
	for i=1,self.n do
		if self[i] ~= other[i] then
			return false
		end
	end
	return true
end
function meta:__tostring()
	local t = {}
	for i=1,self.n do
		t[i] = tostring(self[i])
	end
	return '('..table.concat(t, ', ', 1, self.n)..')'
end
local M = {
	meta = meta,
	wrap = wrap,
	new = new,
}
return setmetatable(M, {__call = function(_,...) return new(...) end})

See also

A similar approach by Renato Maia: http://www.tecgraf.puc-rio.br/~maia/lua/tuple/

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Last edited February 28, 2012 2:55 pm GMT (diff)