Why exceptions for error handling is so important

[Matthias Bentrup via Digitalmars-d]

On Monday, 12 January 2015 at 13:54:18 UTC, Ola Fosheim Grøstad 
wrote:
> On Monday, 12 January 2015 at 13:25:26 UTC, Adam D. Ruppe wrote:
>> On Monday, 12 January 2015 at 11:43:26 UTC, Ola Fosheim 
>> Grøstad wrote:
>>> Does this mean that D will get fast EH?
>>
>>
>> It is fast already...
>
> What makes you say that? Doesn't D still use the standard 
> zero-cost EH that was created for Itanium, where you take the 
> performance hit on unwinding?

The advantage of return code / union type error handling is that 
the exceptional case is as fast as the successful case.

The disadvantage of return code / union type error handling is 
that the successful case is as slow as the exceptional case.

So which method is faster depends on how exceptional your 
exceptions are.