In defence of _G (Was: Fragile Recursion?)

[Dirk Laurie <dirk.laurie@...>]

>> _G.fact = fact
>
> In Lua 5.2 make that _ENV.fact = fact.  It avoids the silly _G
> convention *and* saves yet another table lookup.  :-)
>

Yes, _G should not be used when _ENV==_G.

But no, _G is not a silly convention.

1. It is a good idea to keep a reference to the original environment
    somewhere.
2. It is a good idea for everybody to use the same name for that
    reference.
3. It is a good idea to allow assignments to that name, so that
    Lua programs that wish provide a different default global
    environment (e.g. to disable some libraries) can do so.
4. _G is as good a choice for that name as any other.

Of course, you must bear in mind that _G is just _ENV._G.