Quickie example for object-style programming Lua

mtclasses.lua

--See http://www.lua.org/pil/16.html and http://www.lua.org/pil/16.1.html for more information

--Table for all "methods" shared between "objects"
local objMTindex = {}

--method called "greet"
function objMTindex:greet()
	print("Hello from ", self, "aka", self.aka)
	self.greeted = true
end

local objMT = {
	-- when table indexing fails, try looking in objMTindex.
	__index = objMTindex
}

function Obj(myname) -- "constructor"
	return setmetatable({aka = myname, greeted = false}, objMT)
end

-- Construct two instances
a = Obj("the awesome object a")
b = Obj("the awesome object b")

-- Data access
print("a.greeted:", a.greeted)

-- Method call
a:greet()


-- Data access showing mutated state
print("a.greeted:", a.greeted)


-- Data access showing independent state for each object
print("b.greeted:", b.greeted)