On 5/26/17 2:58 PM, Atila Neves wrote:
On Friday, 26 May 2017 at 11:50:40 UTC, Steven Schveighoffer wrote:
On 5/26/17 4:49 AM, Walter Bright wrote:
On 5/25/2017 4:54 PM, Atila Neves wrote:
I think maybe the problem isn't with `throw` but with `catch`. What if
instead we make it so that:
catch(scope T ex) { /*...*/; }
Means:
catch(scope T ex) { /*...*/; ex.__dtor; }
The trouble comes in when one starts copying exception references
around. Who then is responsible for destroying it?
This isn't the trouble. The trouble is that `new Exception` is not
@nogc, and there isn't a way to fix all existing exception code easily.
True, but a hypothetical `NoGcException.create` _is_ `@nogc` (same as my
MallocException), and is there really any difference between
reading/writing `new Foo` and `Foo.create`?
There isn't, but Foo.create doesn't exist in current code. Someone has
to go through it all and update.
Note that the implication in your strawman is that you need a special
exception to be nogc. I'd rather leave the (de)allocation of the
exception up to the thrower/catcher, and have the exception not care
about its own location.
Also, there's `enforce`, which is where I suspect a lot of throwing
happens anyway. It could use DbI to figure out from the exception type
what to do.
Good point, we could change enforce, and that would fix a lot of the
usage of exceptions.
My $0.02: Either we are going to make `new Exception` be @nogc, or we
are going to require people to type something different.
Or be able to customise `new T`, which feels less hacky than it
magically meaning something different if the type is a Throwable. I know
that there were class allocators in D1 and that they're depecreated but
I wasn't around back then to know why.
Deprecated, but still there.
However, it's the auto-destruction that isn't there. There isn't a way
to tell the compiler to destroy on the catch scope automatically.
Currently, when you override class allocation, you need to explicitly
delete.
-Steve
