D is dead

[Walter Bright]

On 8/23/2018 8:53 PM, David Nadlinger wrote:
> On Thursday, 23 August 2018 at 23:27:51 UTC, Walter Bright wrote:
>> D deals with it via "chained exceptions", which is terrifyingly difficult to 
>> understand. If you believe it is understandable, just try to understand the 
>> various devious test cases in the test suite.
> 
> I don't think that assessment is accurate. Yes, I ported EH to a few new targets 
> and wrote the first correct implementation of exception chaining for LDC, so I'm 
> probably a couple of standard deviations off the average D user in that regard. 
> But said average D user doesn't care about most of the nuances of this problem, 
> like the details of implementing exception chaining without allocating too much, 

I find myself unable to explain the rationale of the behavior exhibited by the 
current chaining system. I dared not change it, as I presumed somebody surely 
built a store around it. It does not simply chain exceptions.


> or which exceptions take precedence in various intentionally twisted test cases.

The only documentation for this is the test suite itself, which does not have 
any documentation or rationale either, just tests.

I would appreciate it if you did document what it's supposed to do and why, as 
likely nobody else knows. Maybe if I understood why I'd be more forgiving of it :-)


> What they do care about is that the fact that an error has occurred is 
> propagated sensibly in all cases without requiring extra attention, and that 
> information as to the origin is not lost (hence chaining rather than just 
> replacement). Heck, the fact that we still don't have default backtrace handlers 
> that consistently work on all platforms is probably a much bigger problem than 
> the minutiae of exception chaining behaviour.

I wish the minutiae was documented somewhere :-( as I care about the nuances of 
it, if only because I'm ultimately responsible for keeping it working correctly.


> All this is not to say that nothrow constructors aren't a good idea, though.

Not much point to debating that, as they're here to stay.