On Friday, 13 February 2015 at 19:10:00 UTC, Adam D. Ruppe wrote:
On Friday, 13 February 2015 at 19:03:10 UTC, Jonathan Marler
wrote:
T construct(T,A...)(void* buffer, A args)
{
return (cast(T)buffer).__ctor(args);
}
This is wrong, you need to initialize the memory first to the
proper values for the class, gotten via typeid(T).init.
std.conv.emplace does this correctly, either use it or look at
its source to see how to do it.
That's what I was looking for! Thanks.
ubyte[ __traits(classInstanceSize, Exception)]
exceptionBuffer;
When the stack unwinds, this will be invalidated... I don't
think stack allocated exceptions are ever a good idea. I don't
think malloc exceptions are a good idea either, the catcher
would need to know to free it.
You might preallocate a pool of GC'd exceptions though, then
throw the next one in the list instead of making a new one each
time.
Yes I am aware of these things. Stack allocated exception are
dangerous if you let them get thrown above the function they were
allocated in. But this is easy to prevent by simply making sure
you catch the exception in the function you allocate it in. And
yes malloc'd exceptions would be odd since the convention is to
allocate them on the GC heap so no one would think they had to
free them. Also you could use a global...but I'm also aware of
the caveats of this, between excessive TLS memory and the dangers
of using shared or __gshare memory. A pool of pre-allocated
exceptions is an idea I was throwing around...but with this new
emplace function it opens up my options. Thanks.
