Re: __gc visible to lua code...

[Graham Wakefield <lists@...>]

On Mar 30, 2007, at 11:09 AM, Tomas Guisasola Gorham wrote:

> > > I think it is best to just keep track of the state of your userdata
> > > and any associated resources. For example: if your userdata is a
> > > struct, add a field to mark when it is finalized. If your userdata
> > > is a boxed pointer, make sure you nullify the pointer when you are
> > > done with it.
> 	We do exactly this in the implementation of LuaSQL.
>
> > Yes, I've done this now... but still I think __gc should be private
> > by default.
> 	In LuaSQL, the `close' method and the `__gc' metamethod are
> the same C function.  Do you have a better idea?

Well there's no harm having a close method; so long as it makes sense  
to retain a LuaSQL userdata reference that is no longer connected.   
Otherwise, I thought setting the userdata to nil would be the  
equivalent.

I thought that __gc was a callback to let you know that the userdata  
is no longer referenced in Lua and will be deleted.  But having it as  
a public method, simply means that __gc is a callback to say that  
either the userdata is no longer referenced, or someone called __gc 
(); it's less well defined.