From 54c1f2d761b506132a709a7e8573c7b54d048cf0 Mon Sep 17 00:00:00 2001 From: David Herrmann Date: Sat, 5 Sep 2015 13:03:59 +0200 Subject: [PATCH] CODING_STYLE: mandate alphabetical include order systemd-internal headers must not rely on include order. That means, they either must contain forward-declarations of used types/functions, or they must include all dependencies on their own. Therefore, there is no reason to mandate an include order on the call-side. However, global includes should always be ordered first. We don't want local definitions to leak into global includes, possible changing their behavior. Apparently, namespacing is a complex problem that people are incapable of implementing properly.. Apart from "global before local", there is no reason to mandate a random include order (which we happen to do right now). Instead, mandate alphabetical ordering. The current rules do not have any benefit at all. They neither reduce include-complexity, nor allow easy auditing of include files. But with alphabetical ordering, we get duplicate-detection for free, it gets *much much* easier to figure out whether a header is already included, and it is trivial to add new headers. --- CODING_STYLE | 28 +++++++++------------------- 1 file changed, 9 insertions(+), 19 deletions(-) diff --git a/CODING_STYLE b/CODING_STYLE index a96ddd3598..f13f9becbc 100644 --- a/CODING_STYLE +++ b/CODING_STYLE @@ -295,25 +295,15 @@ EXIT_FAILURE and EXIT_SUCCESS as defined by libc. - The order in which header files are included doesn't matter too - much. However, please try to include the headers of external - libraries first (these are all headers enclosed in <>), followed by - the headers of our own public headers (these are all headers - starting with "sd-"), internal utility libraries from src/shared/, - followed by the headers of the specific component. Or in other - words: - - #include - #include "sd-daemon.h" - #include "util.h" - #include "frobnicator.h" - - Where stdio.h is a public glibc API, sd-daemon.h is a public API of - our own, util.h is a utility library header from src/shared, and - frobnicator.h is an placeholder name for any systemd component. The - benefit of following this ordering is that more local definitions - are always defined after more global ones. Thus, our local - definitions will never "leak" into the global header files, possibly - altering their effect due to #ifdeffery. + much. systemd-internal headers must not rely on an include order, so + it is safe to include them in any order possible. + However, to not clutter global includes, and to make sure internal + definitions will not affect global headers, please always include the + headers of external components first (these are all headers enclosed + in <>), followed by our own exported headers (usually everything + that's prefixed by "sd-"), and then followed by internal headers. + Furthermore, in all three groups, order all includes alphabetically + so duplicate includes can easily be detected. - To implement an endless loop, use "for (;;)" rather than "while (1)". The latter is a bit ugly anyway, since you probably really