Re: Pushing a UserData pointer?

[Chris Marrin <chris@...>]

Rici Lake wrote:

> ...
> That's a cool idea. You could even stash a reference count in the 
> userdata before the actual object itself, and then let Lua do all the 
> memory management (aside from maintaining the reference count, of 
> course). That would allow a standard memory management regime for both 
> shared objects and objects only referenced by Lua.
>
> I'd use a fully-weak table rather than a weak-valued table; it would 
> have much less impact on gc.

yes, a weak table worked well when I was using it. But it was two table 
lookups. Seems to me that a lua_pushuserdata() implementation beats all 
that to death (at least in my test cases so far). And, if you use an 
opaque handle for the userdata rather than a void*, it can be as type 
safe as passing around the lua_State.

I have to say that the trick of combining the userdata with the C++ 
instance data by overriding the new operator in C++ is incredibly cool. 
Now I have one structure that can be used by both C++ and Lua and 
lua_pushuserdata() allows it to be totally efficient. Thanks to Ben for 
that hack!

--
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