A window demo in lua. __index

window.lua

Window = {} -- create a namespace

-- create the prototype with default values
Window.prototype = {x=0, y=0, width=100, height=100}
Window.mt = {} --create a metatable

--declare the constructor function
function Window.new( o )
  setmetatable(o, Window.mt)
	return o
end

Window.mt.__index = function ( table, key )
	return Window.prototype[key]
end

w = Window.new{x=10, y=20}
print(w.width)

print(w.x)
print(w["x"])