Re: Lua 5 getglobals

["Peter Hill" <corwin@...>]

Peter Hill:
> Why does "setglobals" not work on C-functions? Is this deliberate (seems
> unlikely) or due to some implementation problem?

Roberto Ierusalimschy:
> It is deliberate. All C functions share a common environment table
> (new name for the old "table of globals", as they are not globals).
> A "setglobals" for a C function would change the environment of all
> C functions, but would not affect Lua functions (as they have their
> independent environments). This is difficult to explain, and does not
> seem very useful.

So it is basically an implementation limitiation (rather than a 'design
feature').

I'm not sure how often one might want to set the globals of a C function
(and in practice one could always just wrap it in a Lua function) but the
limitation does cause Lua to behave in a non-intuitive & unpredicable
fashion.

Afaik, one can't test in Lua5 whether a function is native Lua or C... and I
find it rather unsettling that if someone chose to replace a Lua function
with a compiled version then the behaviour of my program might completely
change.

These new function-globals seems to be a very powerful & useful addition to
Lua :-) ... but this non-homogeneity in behaviour seems to unnecessarily add
complexity to the system's behaviour. How expensive would it be to
homogenise it?

*cheers*
Peter Hill.

Ki: Contractors... high-paid leeches stealing our work.
Fooker: If you think of them as disposable employees, you'll feel much
better...