--nextPart1739792.OuyeAkC2fj
Content-Type: text/plain;
  charset="iso-8859-15"
Content-Transfer-Encoding: quoted-printable
Content-Disposition: inline

On Friday 15 June 2007, Michael Olbrich wrote:
> Please don't use "" for _any_ installed header. This can result in very
> confusing errors.

My statement was: Please don't use <> for _any_ installed header. This can=
=20
result in very confusing errors.

> ----- /usr/include/a/foo.h --------
> #include "bar.h"
> ...
> -----------------------------------
>
> ----- /usr/include/a/bar.h --------
> // something
> -----------------------------------

I'd assume a/foo.h and a/bar.h to belong to the same lib or at least libs t=
hat=20
have some relation (like kdecore and kdeui). That means if I include a head=
er=20
of that lib I want all the dependent headers from the same version of that=
=20
lib.

I.e. if I include <foo.h> (knowing it'll pick the header a/foo.h) then I'd=
=20
expect it to include all dependent headers from a/ and not some other versi=
on=20
or even other unrelated lib in some other dir.

> ----- /usr/include/b/bar.h --------
> // something else
> -----------------------------------
>
> /usr/include/b/foo.h does _not_ exist.
>
> ----- test1.c ---------------------
> #include <foo.h>
> ...
> -----------------------------------
>
> ----- test2.c ---------------------
> #include <bar.h>
> #include <foo.h>
> ...
> -----------------------------------
>
> compiling with -I/usr/include/b/ -I/usr/include/a/

test1.c I'd expect to always compile fine. I'd expect test2.c to fail only =
if=20
a/bar.h and b/bar.h use the same include guard. (Now here's a good reason w=
hy=20
you should namespace your include guard, too. E.g. all my Phonon headers ha=
ve=20
guards of the form PHONON_CLASSNAME_H.) If a and b are incompatible version=
s=20
of the same lib then you're supposed to get compile errors - if you don't=20
debugging can get really hairy.

> gets different=20
> results for test1.c and test2.c. That is imho wrong. The order in which
> headers are included and whether they are included directly or
> indirectly (via another header) should never change the result.

Can you make your example a bit more concrete? So far it looks designed to=
=20
break. Any real world examples?

Have you read the rationale on=20
http://techbase.kde.org/Policies/Library_Code_Policy#As_library_developer ?

=2D-=20
________________________________________________________
Matthias Kretz (Germany)                            <><
http://Vir.homelinux.org/
MatthiasKretz@gmx.net, kretz@kde.org,
Matthias.Kretz@urz.uni-heidelberg.de

--nextPart1739792.OuyeAkC2fj
Content-Type: application/pgp-signature

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.6 (GNU/Linux)

iD8DBQBGc7A3yg4WnCj6OIoRAldOAJ9RwTHQHZkNuddoON2mtNEeksVuNgCcDUfm
3AMy277il73ga0k3WNO5UcE=
=8HrH
-----END PGP SIGNATURE-----

--nextPart1739792.OuyeAkC2fj--