Am Donnerstag, dem 05.10.2023 um 12:25 -0400 schrieb Aaron Ballman via Liaison:
> On Thu, Oct 5, 2023 at 12:04 PM Niall Douglas via Liaison
> <liaison_at_[hidden]> wrote:
> >
> > On 05/10/2023 16:09, Aaron Ballman via Liaison wrote:
> >
> > > The syntax that looks like `pre (i >= 0)` is slightly problematic in C
> > > in that it's using an unreserved identifier. However, I think that's
> > > pretty easy to work around by introducing it as `_Pre` in C and
> > > providing something like a `<stdcontracts.h>` with a macro so you can
> > > get the `pre` spelling in header code shared between C and C++.
> > Surely these can be made context sensitive keywords, so if somebody uses
> > `pre` or `post` anywhere else, that's fine? If so, do we really need
> > _Pre and _Post?
>
> C doesn't have the notion of context sensitive keywords, so that would
> be a novel thing for us. I have no idea how palatable the concept is
> to the committee.

Can we just make these attributes? Then it does not have to be a
keyword and we get the __pre__ and __post__ versions automatically.

Martin


>
> > That would leave the people who define preprocessor macros `pre` and
> > `post`, but whether on C++ or C++ that would have the same outcomes.
>
> WG14 makes every effort to avoid breaking user code, even when that
> code is in macros. C has a reserved identifier namespace that's
> different from C++; in C, leading-double-underscore or
> underscore-followed-by-capital-letter identifiers are reserved for any
> use, whereas in C++ they're reserved "for the implementation". So in
> C, we generally make use of reserved identifiers to avoid breaking
> users when adding a keyword. (We don't always though -- for example,
> we added `typeof` in C23 which is not in the reserved identifier
> namespace, but we also could not find any evidence of users using that
> identifier, probably because of how ubiquitous the extension is in the
> marketplace.)
>
> ~Aaron
>
> > Also, for the record, I agree with Aaron that contracts are probably
> > even more useful for C than for C++. There is a whole bunch of C which
> > would benefit greatly from them.
> >
> > I also concur that I prefer this syntax to an attributes based one.
> >
> > Niall
> > _______________________________________________
> > Liaison mailing list
> > Liaison_at_[hidden]
> > Subscription: https://lists.isocpp.org/mailman/listinfo.cgi/liaison
> > Link to this post: http://lists.isocpp.org/liaison/2023/10/1225.php
> _______________________________________________
> Liaison mailing list
> Liaison_at_[hidden]
> Subscription: https://lists.isocpp.org/mailman/listinfo.cgi/liaison
> Link to this post: http://lists.isocpp.org/liaison/2023/10/1226.php