On Saturday, 18 August 2012 at 17:55:22 UTC, Michel Fortin wrote:
As for structs, you could do it the same way, but I don't think
you'd get enough benefit to compensate the drawback in
performance and elsewhere. To truly have non-fragile structs
you'd need to disable almost all compile-time introspection
too. That would be very disruptive.
So I don't think it makes sense to have non-fragile structs.
Can't D allocate classes on the stack, in some circumstances?
Would this lead to the same problems that you just described, or
is the problem caused by how structs and classes are used, rather
than how they're implemented?
By the way, did you take a look at the benchmarks?
<http://michelf.ca/blog/2009/vtable-benchmarking/>
Those are some pretty interesting numbers - seems as though the
overhead is only about 10% - 20% over that of a regular vtable
dispatch? I would have guessed that it would almost double the
overhead, but I suppose that most of the overhead of a function
call comes from saving registers, managing the stack, etc.
The overhead is so small, in fact, that I'd feel quite
comfortable using it in a very performance-sensitive situation
(like, say, a rasterizer library), presuming that your benchmarks
were accurate. Another strong argument in favour of trying to
have this system implemented :)
