Why exceptions for error handling is so important

[via Digitalmars-d]

On Tuesday, 13 January 2015 at 20:58:43 UTC, deadalnix wrote:
> On Tuesday, 13 January 2015 at 19:36:31 UTC, Marc Schütz wrote:
>> On Monday, 12 January 2015 at 23:01:53 UTC, Ola Fosheim 
>> Grøstad wrote:
>>> On Monday, 12 January 2015 at 22:06:32 UTC, deadalnix wrote:
>>>> No, Exception are a bail out mechanism. It is the, I have no 
>>>> idea what to do about this mechanism.
>>>
>>> The way it is done in C++, yes.
>>>
>>>> If you put aside performance concerns, exceptions for 
>>>> control flow also tend to make many code path implicit and 
>>>> makes for very unreadable/unmaintainable code.
>>>
>>> But exceptions are control flow. There is no such thing as 
>>> normalized control flow, all state changes implies "control 
>>> flow". Think in terms of a state machine. You could just 
>>> remove all variables and only have a big state machine 
>>> (assuming finite dimensions). Every single state transition 
>>> implies flow of control.
>>>
>>> The control flow you see in the source code is just the 
>>> programmer's "rendition" of control flow. Exceptions is a 
>>> mechanism for getting cluttering resolution out of that 
>>> rendition to make the code more readable and maintainable. 
>>> The goal is to retain the meat of the computation and remove 
>>> the noise.
>>>
>>> Or to put it differently, there are many ways to write the 
>>> same function. Good use of exceptions removes the clutter and 
>>> leaves the things you care about visible. It's a mechanism, 
>>> not a moral issue or a religion.
>>>
>>> So there is nothing wrong with throwing HTTPStatus(409) or 
>>> HTTPStatus(201), even though it returns state to the 
>>> environment. If that means the code is more maintainable and 
>>> more likely to be correct, then that is good use of the 
>>> mechanism.
>>
>> I usually don't do this, but I really need to post a "+1" here:
>>
>> +1
>
> Too bad you chose to do this on a bad strawmman.

Your claims:

- Exceptions are for "I have no idea what to do about this" 
situations.
- "exceptions for control flow [...] makes for very 
unreadable/unmaintainable code"

Ola's answer directly addresses these claims and provides a 
counter-example (in the last paragraph), which I happen to agree 
with.

=> Not a strawman.