10.10.2012 12:50, Lorenzo Caminiti wrote:
On Wed, Oct 10, 2012 at 12:57 AM, Andrzej Krzemienski <akrzemi1@gmail.com> wrote:
P.S. I just have wild idea - what about axioms for function's arguments? i.e. not on types, but on values. Maybe some kind of axiomatic_assert. For instance that can be used to prevent pointers aliasing ("restrict" keyword in C99): void* memcpy( void* dest, const void* src, size_t count ) { axiomatic_assert( do_not_overlap(dest,src,count) ); // ... }
Is this not the same thing as preconditions in contract programming and Lorenzo's Boost.Contract library? I think it is
I supposed that axiomatic_asserts MUST be never checked. For instance, because such conditions may not be true in all cases, like in concept's axioms (however, there are several different opinions in this regard).
(of course, Boost.Contract preconditions are better because in declarations, const-correct, etc).
I do not restrict axiomatic_assert to function's body, some kind of similar feature may appear in declarations too. Main idea is to have general mechanism to give away some portions of semantic, in a favour of performance - to sign a contract with compiler's optimizer. Concept's axioms are applied only to types, but not to specific variables. While axiomatic_assert can be used to state semantic relations on specific set of variables.
On this topic, I still didn't give up the desire of generating preconditions from axioms and checking them at run-time.
In general, do you think that C++ axioms MUST always be preserved? Best Regards, Evgeny