Re: Calling C++ class methods from Lua (newbie)

[Rici Lake <lua@...>]

On 15-Oct-05, at 5:51 PM, David Given wrote:

> ...actually, a thought: if I were to run Lua in an environment managed 
> by a
> *real* garbage collector, lik the Boehm libgc, would it be worth my 
> while to
> disable Lua's own garbage collector? If so, how?

That's an interesting question.

First of all, if I had written Lua's garbage collector, I would have 
taken
offence to your use of *real*. The Lua GC is a real garbage collector, 
and
quite a reasonable one. It suffers from not being integrated with a 
memory
allocator, perhaps, but the consequence is that it is fully portable.

Nonetheless, one might wish to integrate Lua's memory management with 
the
memory management available in some external environment. This will 
prove
to be tricky, because the Lua data structures used to support its 
garbage
collection are also used for other purposes.  So it would be necessary 
to
disentangle some of the linked lists.

Beyond that, the Lua garbage collector performs some tasks which are 
quite
specific to Lua's semantics. For example, the Boehm garbage collector 
does
not really have any mechanism equivalent to Lua's weak tables, or even 
any
mechanism which could easily be used to implement weak tables.  And, 
while
the Boehm collector can implement finalization, it does not do so in a 
way
consistent with Lua's (arguably idiosyncratic) semantics, which could, 
in
theory, be used to change, add or delete __gc metamethods during the 
life
span of an object, something not normally contemplated by finalization
mechanisms.

That's not to say that it couldn't be done, of course.