DIP33: A standard exception hierarchy

[Michel Fortin]

On 2013-04-02 11:59:39 +0000, Dmitry Olshansky <dmitry.olsh at gmail.com> said:

> 02-Apr-2013 15:35, Andrei Alexandrescu пишет:
>> On 4/2/13 7:24 AM, Dmitry Olshansky wrote:
>>> You might want to add Visitor pattern to Exceptions but it's darn messy
>>> to deal with and is an overkill most of the time.
>> 
>> Actually I think that's a good thing to do.
>> 
> 
> Why would be that? It doesn't solve the key problem of "try clause plus 
> a ton of semi-identical catches" used just to perform a mapping of X 
> handlers to Y subsets of errors. Plus visitor does the same dispatch 
> that is already addressed by exception handlers (or partly so).

What would be nice is some syntactic sugar for the following pattern:

	void handler(CommonExceptionType e)
	{
		// do something with exception
	}

	try { … }
	catch (FooException e) { handler(e); }
	catch (BarException e) { handler(e); }
	catch (BazException e) { handler(e); }

That could become:

	try { … }
	catch (CommonExceptionType e in FooException, BarException, BazException)
	{
		// do something with exception
	}

I've been secretly wishing for something like this, and not just in D.

-- 
Michel Fortin
michel.fortin at michelf.ca
http://michelf.ca/