Re: Lua addition proposal: Userdata as function environment

[Rici Lake <lua@...>]

On 4-Oct-06, at 4:38 PM, Sam Roberts wrote:

> On Wed, Oct 04, 2006 at 03:24:53PM -0500, Rici Lake wrote:
> > Why not just use an empty table whose __index and __newindex methods
> > use the userdata? In effect, they could be the same __index and
> > __newindex metamethods you would use with the userdata.
> >
> > The following hardly changes your example at all:
> >
> > (Note: I'm using lightuserdata here, something I would normally never
> > do, but you don't seem to be attaching a __gc metamethod to your
>
> I'm confused. I thought lightuserdata doesn't have an individual
> metatable?

They don't. The lightuserdata is passed to the __index and __newindex 
methods by being placed in an upvalue. The metatable is actually 
attached to an ordinary, empty Lua table, which is what is returned by 
pushobject.

Note: I haven't actually *tried* this code. It probably doesn't work. :)

Other Note: I almost never use lightuserdata; I would normally have 
created a full userdata and attached a __gc metamethod to it.