[OT] - C++ exceptions are becoming more and more problematic

[H. S. Teoh]

On Thu, Feb 24, 2022 at 06:02:31AM +1300, rikki cattermole via Digitalmars-d wrote:
> On 24/02/2022 5:59 AM, IGotD- wrote:
> > The Herb Sutter exception/return value proposal would live alongside
> > with the old exceptions. I suspect that D would do the same thing.
> 
> Yes, with the possibility of having the compiler swap the runtime
> unwinding stuff for value based where possible.
> 
> Apart from some situations where you need to be able to store a class
> based exception, I don't see why it couldn't work like this.

If we had by-value exceptions, we can implement the current by-reference
exceptions simply by treating the reference to the allocated exception
as the value to be thrown. I.e.,

	throw new Exception(...);

is equivalent to:

	struct S {
		Exception e;
	}
	Exception e = new Exception(...);
	throwByValue S(e);

So if we implemented by-value exceptions, we don't have to break any
existing code, just treat `throw new SomeException` as syntactic sugar
for some analogue of the above.


T

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