Why exceptions for error handling is so important

[deadalnix via Digitalmars-d]

On Monday, 12 January 2015 at 18:07:55 UTC, Adam D. Ruppe wrote:
> On Monday, 12 January 2015 at 17:57:10 UTC, H. S. Teoh via 
> Digitalmars-d wrote:
>> Still, #9584 had some discussions about doing lazy stack trace
>> construction, which was costing most of the time, but I don't 
>> remember if that was actually implemented.
>
> Yea, it was (I did it myself for posix, someone else did it on 
> Windows), led to gigantic speed boosts, unless you are printing 
> the trace, of course, when it has to be generated.

Can you elaborate on the technical details of that stunt ? When 
you need to build the trace, you often have unwinded part of the 
stack, so it does seems hard to build it lazily.