Re: Lua 5.2 - emulation of old setfenv

[Peter Cawley <lua@...>]

On Wed, Jan 5, 2011 at 5:05 PM, Lorenzo Donati
<lorenzodonatibz@interfree.it> wrote:
> In doing this I assumed that _ENV is always the first upvalue of a function.
> Reading 5.2 docs it seems true, but I remember some old post in which
> Roberto (or maybe Luiz?) said it isn't always like that (but maybe I
> remember something superseded by newer work versions).

_ENV is always the first upvalue of a chunk (i.e. a function created
by passing a piece of non-bytecode source code to lua_load), but this
is not true for functions in general. Functions in general may or may
not have an upvalue called _ENV, which may or may not be a shared
upvalue, and if they do have an _ENV upvalue, it doesn't have to be
the 1st upvalue.