Re: copy a table

[manel <lista@...>]

On Mon, 29 Jan 2007, Thomas Hafner wrote:

> Hello,
>
> what's the easiest way to copy a given table?
>
> If variable ``source'' references the table, just the assignment
>  target = source
> won't do it: no new table will be constructed, but ``target'' will
> reference the same table as ``source'' (e.g. after the assignment
> target[1]=42, source[1] will be set to 42, too).
>
> Regards
>  Thomas

Hello Thomas

There is no simple way of copying a table in the most general case
(because tables can self-reference). A simple one (which does not
treat well self-references) is:

function tablecopy (t)
   local tc = {}
   if type(t) == "table" then
      for k, v in pairs(t) do
         tc[k] = tablecopy(v)
      end
   else
      return t
   end
   return tc
end

-- example
t = {c = "a", "b", {1, 2, 3}}
tc = tablecopy(t)


But you could take a look at http://lua-users.org/wiki/CopyTable,
much better.

Manel