Re: Userdata with methods *and* table access.

[David Jones <drj@...>]

On Oct 14, 2004, at 20:52, Rici Lake wrote:

> On 14-Oct-04, at 2:39 PM, Tom Spilman wrote:
>
> >  I was considering hashes, but doesn't Lua internally keep a hashed 
> > version
> > of the string?  Is there a way to get to that?  Or can I count on the 
> > const
> > char pointer returned from lua_tostring to be the same for the same 
> > strings
> > (this sounds really hacky)?  As it is now my innermost scripted loops 
> > are
> > doing string compares at the binding layer which makes them less 
> > efficient
> > than they could be with a good hash.
>
> You can count on the char pointer to be the same provided the string 
> never gets garbage collected. (i.e., if you keep a reference to the 
> string somewhere.)

The official line is that this is true only whilst the lua string that 
is passed to lua_tostring remains on the (Lua) stack.  In other words 
Lua reserves the right to implement a moving memory manager.  Of 
course, all the current implementations will never move the string.  So 
it's okay.

David Jones