Re: Bizarre behavior with debug.setupvalue() in Lua 5.3

[Sean Conner <sean@...>]

It was thus said that the Great Paul K once stated:
> Hi Sean,
> 
> > I think what caught me up is that I haven't really played with Lua 5.2 (or Lua 5.3 until a few days ago) and I was still kind of expecting the Lua 5.1 behavior with setfenv(), which is a "local" change of a function's environment, and not the global change that happens now (because upvalues are pointers).
> 
> You can still keep it isolated if you want:
> 
> local meta
> do
>   local _ENV = _ENV -- localize it as needed
>   meta = {
>     io       = io,
>     tostring = tostring,
>     select   = select,
>     print    = function(...)
>       io.stdout:write("HERE I AM, JH ... ")
>       for i = 1 , select('#',...) do
>         io.stdout:write(tostring(select(i,...)),"\t")
>       end
>       io.stdout:write("\n")
>     end
>   }
> end
> print(debug.setupvalue(meta.print,1,meta),meta)
> print(debug.getupvalue(meta.print,1))
> 
> This prints without errors under both Lua 5.2 and Lua 5.3:
> 
> _ENV    table: 0092B810
> _ENV    table: 0092B810
> 
> Or is this not what you wanted in the first place?

  This is indeed what I wanted.  Thank you.

  -spc