Re: [Fresco-devel] Coding standard: throw specifications

Neil Pilgrim wrote:
> Nathaniel Smith wrote:
> 
>>On Sun, Jan 05, 2003 at 10:12:42AM +0000, Neil Pilgrim wrote:
> 
> 
>>Throw specifications mean very different things in IDL and C++
>>(reasonably, considering that the exception handling systems are
>>totally different too...).  In IDL, throw specs are a way of
>>_enabling_ exceptions -- you can only throw exceptions that you have
>>throw specs for.  In C++, throw specs are a way of _disabling_
>>exceptions -- you guarantee that you'll never throw any exception
>>besides those listed (enforced by crashes, IIRC).  The two systems are
>>quite orthogonal.
> 
> 
> I completely agree...almost...but you might say that throw specs are a
> way of enabling *user* exceptions - I believe that with corba you can
> throw some SystemExceptions, eg. OBJECT_NOT_EXIST? ;)

you shouldn't. Users shouldn't throw anything but user exceptions.

> - generally don't bother with exception specifications

I think exception specs are good to document the intention (similar
to 'const'), but they may be hard to fulfill. If you can really
guarantee that only std::runtime_error will be thrown, you may as well
embed that statement into the API.

> - except possibly throw() on non-inline non-virtual non-template
> functions

huh ?


>>In IDL, of course, it's a different beast; use them whenever you want
>>to let a method throw an exception (and throwing an exception is
>>generally considered to be a good way to signal an error, no?).
> 
> 
> I agree with this entirely...except that the caller may exit wrongly all
> over the place if the exception is not caught. Of course that may be a
> 'good thing', ie. you should always include error-handling, *especially*
> with corba, where exceptions can come from any call...

exactly. You can only declare user exceptions anyways, which are only
a tiny fraction of all thrown exceptions, see our own code for an illustration.

Stefan