Re: The Right Approach to Exceptions

[Andrei Alexandrescu]

On 2/20/12 10:31 AM, Sean Kelly wrote:
On Feb 20, 2012, at 7:49 AM, Andrei Alexandrescu<seewebsiteforem...@erdani.org> 
 wrote:

Also, I think we can do better than defining the boilerplate constructor (see 
e.g. https://github.com/D-Programming-Language/phobos/pull/439). It's just a 
function. Consider:

// this goes in the stdlib
void raise(ConcreteException)(string message, Throwable t = null, string f = 
__FILE__, size_t l = __LINE__)
{
  auto r = new ConcreteException;
  r.message = message;
  r.file = f;
  r.line = l;
  r.next = t;
  throw r;
}

class AcmeException : Exception {}

Now whenever you want to raise AcmeException, you say 
raise!AcmeException("message"). Also, raise may accept additional data that 
fills the Variant[string]. That makes exception definitions one-liners.

What is gained here over the current approach:

throw new AcmeException("message");

Just eliminate the need for the ctor definition in the exception class?

Also possibly the definition of other constructors that set state. It's 
simple factorization.

Andrei