On 22/04/2014 5:14 PM, Coroutines wrote:
On Tue, Apr 22, 2014 at 12:09 AM, Philipp Janda<siffiejoe@gmx.net> wrote:>>What I gain is the ability to verify the type safety of light userdata >>usage on the C sideAhah! I get what's going on ITT now. :-) Maintain a vector of addresses that are copies of the lightuserdata for the particular type you're checking for. Keep it sorted for binary-searching it later. Not as light as what you're suggesting, but it wouldn't require modifying Lua if this proposal doesn't get accepted :>
Yep, or a hash table. Or you could use spare bits of the C pointer as was suggested earlier.Or if your objects are allocated from a slab you can do a pointer range check. Sorry to change my tune, but more and more I am thinking that the killer feature of this patch is the ability to have multiple classes of light userdata each with their own metatable. This allows operator overloading for a particular class. Which would be neat if one of your light userdata happened to have algebraic structure.
Ross.