DIP33: A standard exception hierarchy

[Jonathan M Davis]

On Tuesday, April 02, 2013 17:56:07 Lars T. Kyllingstad wrote:
> On Monday, 1 April 2013 at 22:26:39 UTC, Jonathan M Davis wrote:
> > In general, I'd strongly suggest having subclasses for
> > the various "Kind"s in addition to the kind field. That way,
> > you have the
> > specific exception types if you want to have separate catch
> > blocks for different
> > error types, and you have the kind field if you just want to
> > catch the base
> > exception.
> 
> Then you'd have two points of maintenance when you wish to add or
> remove an error category.

True, but it's also trivial to do. But if we had to decide between basically 
putting error codes on exceptions and using sub-classes, I'd vote for 
subclasses in most cases - though errno would need to go the error code in the 
exception route, since it has different meanings in different contexts and would 
risk an absolute explosion of exception types anyway; though it should 
probably be translated to a more meaningful exception based on context with 
the errno exception being chained to it - which is what you suggest in the DIP 
IIRC. In general though, I'd favor subclasses, and I don't think that it's all 
that big a deal to give them each specific error codes when you want the base 
class to have an error code like you're suggesting.

- Jonathan M Davis