Re: [boost] Boost.Function variant needed

From: Douglas Gregor (gregod_at_[hidden])
Date: 2001-11-14 23:50:20

On Wednesday 14 November 2001 06:00 pm, you wrote:
> You can call handle_exception with an arbitrary function object that has a
> "signature" PyObject* f(), and it will work without allocating any memory
> on the heap. The bulk of the code (in handle_exception_impl) is not
> repeated for each different function object type. handle_exception_impl
> doesn't store the function object away anywhere, so it doesn't matter that
> it receives a reference.
>
> I would have liked to be able to leverage the function library for this
> purpose.

I see now what you mean. You want the function library to essentially hold a 
reference/pointer to the function object you pass in and not ever make a copy 
of it.

If this were to be an addition to the function library, would you have a 
preferred form? The only form I can think of would be to reuse the "ref" 
function used by bind, so one would have:

void foo(boost::function<...> func);

template<typename F>
void bar(F f)
{
  foo(ref(f)); // boost::function won't allocate any memory or copy f
}

> > An alternative that would work right now would be to use a custom
>
> allocator.
>
> How would that help?

Well, it can solve the stateless function object problem, but not the problem 
you're facing.

I'd be willing to support the abovementioned syntax.

        Doug