RE: [boost] Re: Virtual inheritance in exception hierarchies

From: Alan.Griffiths_at_[hidden]
Date: 2003-09-08 07:12:52

> -----Original Message-----
> From: David Abrahams [mailto:dave_at_[hidden]]
> 
> > I've never worked on a project of any size where this was even
> > remotely plausible.
> 
> I think it's worth stretching your brain a little bit beyond your own
> experience, especially when designing libraries.

Yes.  But my objection is to stretching it to *exclude* my own experience.

Even if my experience were unrepresentative it does indicate that there are
existing libraries that do not inherit from std::exception.  And that any
attempt to deal with *all* exceptions through a common base class is
unreliable.

I may be misunderstanding your view, but you appear to be saying that client
code having dealt with all the exceptions that it is "expecting" it *may*
deal with "unexpected" exceptions by catching std::exception and use "what"
to get some sort of a message.

In response I am saying that this doesn't address all exceptions and that
there will be exceptions that (unless expected) fall through to the catch
(...).

We differ only in how concerned we are regarding some specimens that
multiply inherit from std::exception which, without virtual inheritance,
fall into the latter category.  I think these are sufficiently rare to be
unimportant, you think they are important.

> Excuse me, but the example was Bjarne's, 

Sorry, I failed to register that.  

> and I don't think your
> disdainful tone is warranted.

I didn't intend to be disdainful - the reference to "mixture of two beasts"
was intended to be amusing.  Sorry that it misfired.

> Then you really must grant that it could reasonably be appealing to
> people who don't use your <disdainful term> MFC pattern of throwing
> pointers to dynamically allocated objects, and can take advantage of
> MI.

Touche!
-- 
Alan Griffiths
http://www.octopull.demon.co.uk/ 
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