Re: exception specifications in the standard library
on Tue Apr 10 2007, "Ivan Novick" <ivan.d.novick-AT-gmail.com> wrote:
On Apr 10, 5:42 pm, David Abrahams <d...@boost-consulting.com> wrote:
The simple fact of the matter is that the standard is haphazard in its
use of throw() to indicate "can't throw anything." Except on a
virtual function, the as-if rule says the appearance of "throw()" in
the specification does not oblige implementations to actually use it.
throw() is used in some places, and in others, the standard says
"throws: nothing." They are -- except in the case of virtual
functions -- equivalent statements. By the time the committee was
ready to do anything disciplined about exception handling in the
standard library, it was too late to make trivial changes like using
one consistent way of saying "doesn't throw," so the inconsistencies
remain as an hysterical artifact.
Interesting.
What is the issue with virtual functions that makes them not
equivalent statements in that case?
There's a user-visible effect when you try to override a virtual
function that has an exception specification: your exception
specification has to be as, or more, restrictive. In the other cases,
the presence of an exception specification has no user-visible effect.
--
Dave Abrahams
Boost Consulting
http://www.boost-consulting.com
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