Re: linked variable

[Rici Lake <lua@...>]

On 1-Dec-06, at 12:31 AM, wang xu wrote:

> Is there a generic way to automatically update one variable when the 
> value of another variable is changed?

No. (And why do you want to do that?)

The closest you can do is to implement your own "boxed" values, using 
tables with a single key (say, 1):

val1 = {"a"}
val2 = val1
val1[1] = "b"
=val2[1]

You could dress it up in O-O notation:

do
  local meta = {}
  meta.__index = meta
  function meta:set(v) self[1] = v end
  function meta:get() return self[1] end

  function Box(v)
    return setmetatable({v}, meta)
  end
end

val1 = Box("a")
val2 = val1
=val2:get()
val1:set("b")
=val2:get()