Re: a new proposal for environments

[Roberto Ierusalimschy <roberto@...>]

> On Wed, Feb 24, 2010 at 6:38 PM, Roberto Ierusalimschy
> <roberto@inf.puc-rio.br> wrote:
> > * Environments for C functions should go too. Actually, they were
> > introduced only to match environments in Lua functions. The old
> > technique of setting a table as a common upvalue for all functions
> > of a library (as done in Lua 5.0) is quite satisfying. (So, the
> > only "environments" left are for userdata, which probably should
> > get a more proper name.)
> 
> Can we still keep the convenience of C environments even if it is now
> an upvalue. Some support for an equivalent system would be nice even
> if the implementation is different.

To use the C environment you only change LUA_ENVIRONINDEX to
lua_upvalueindex(1). To create a group of functions sharing an
"environment", we may reintroduce something along the lines of
luaI_openlib (still in 5.1 to keep compatibility with 5.0): It opens a
C library with all functions sharing a common number of upvalues. (Or
maybe something more specific.)

Do you have anything else in mind?

-- Roberto