Throwable class design

[simendsjo]

On Wednesday, 30 January 2013 at 21:07:41 UTC, Jonathan M Davis 
wrote:
> On Wednesday, January 30, 2013 12:40:26 H. S. Teoh wrote:
>> On Wed, Jan 30, 2013 at 09:03:31PM +0100, rumbu wrote:
>> > Ok, maybe my thoughts are polluted by some C# programming 
>> > practices,
>> > but I learnt that exceptions are never intended for the end 
>> > user
>> > (one of the reasons is that the exception mesages are in 
>> > most cases
>> > displayed in english language). In Windows world, throwing an
>> > exception displays a message with a nice two buttons: Close 
>> > and
>> > Debug. This will make the accountant using my software very 
>> > eager to
>> > click on Debug :)
>> 
>> Maybe that is accepted convention in the Windows world, but I 
>> consider
>> exceptions as an excellent way of conveying what went wrong to 
>> the user.
>> Such as "could not calculate cell value, expecting number in 
>> cell A5 but
>> got 'adfsdfas' instead". Throwing an exception is the cleanest 
>> way to
>> abort potentially deeply-nested calculation code and give the 
>> user a
>> useful message in the meantime. I would hate to manually 
>> propagate such
>> user errors by hand, just because of the convention that 
>> exception
>> messages should never be seen by the user!
>
> I would never show an exception to a user, even in Linux. I 
> might show the
> exception's message, but I would never let the exception escape 
> and end up
> showing the stack trace and whatnot to the user. I see no 
> problem in showing
> an exception's message to a user if that's what it was intended 
> for. The fact
> that it was an exception which delivered the message is an 
> implementation
> detail that the user doesn't care about and shouldn't know. But 
> I suspect that
> the two of you pretty much agree about that but are thinking of 
> different
> things when you're talking about "showing the exception to the 
> user."
>
> - Jonathan M Davis

I would much rather show a stacktrace to the user than "Unknown 
error" or some other little usable message. When a user 
copy/paste a stacktrace for a hard-to-reproduce problem, it's a 
*lot* simpler to fix the error or give a custom error message.