Re: a new proposal for environments

[Duncan Cross <duncan.cross@...>]

On Thu, Feb 25, 2010 at 5:26 PM, Enrico Colombini <erix@erix.it> wrote:
> David Kastrup wrote:
>>
>> Up to now, the difference is quite too much in the "eyes glaze over"
>> department for my taste.
>
> I don't like the idea of reusing the _G name; it could lead to confusion
> because _G and _ENV are quite different beasts. Consider (5.1):

Yes, but while this is certainly true, for what real-world reason does
current code change the value of _G? The only one I'm aware of is to
set it to nil because you don't want people to have an easy reference
to that table for some reason - but if that's the case, they can just
use _ENV to refer to it anyway, so you would still need to change your
code!

I'm all for maintaining back-compatibility whenever appropriate, but
it just seems like people are worried unnecessarily about technical
differences between _G and _ENV when the reality is that (a) they seem
to be there for much the same purpose and (b) pre-5.2 code will
largely need to be reviewed and re-thought-about anyway. Especially if
it uses getfenv/setfenv. Also, Roberto mentioned this earlier in the
thread:

> _ENV = module "libraryname"

...so presumably every Lua module will need to be changed like this
before it will work in 5.2. Unless of course module() will still
change _ENV in the calling script through some trickery?

-Duncan