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<SeeWebsiteForEmail at 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