On Sat, Apr 4, 2020, 1:41 AM Vijay Kumar Banerjee <vi...@rtems.org> wrote:
> > > On Sat, Apr 4, 2020 at 1:22 AM Vaibhav Gupta <vaibhav.varo...@gmail.com> > wrote: > >> CPP directives like: >> 1) #if >> 2) #ifdef >> 3) #ifndef >> 4) #elif >> 5) #else >> 6) #endif >> >> do form code blocks. Since, they don't make use of brackets, >> as a part of C language rule, their nested and repeated use >> can make the code very hard to read. Can even result it >> spaghetti code. >> >> This can be understood by this patch: >> https://lists.rtems.org/pipermail/devel/2020-April/058964.html >> >> The proposed idea is: >> 1) Nested CPP directives should follow same indentation rules >> as of nested conditional statements like 'if' and loops. >> >> 2) To mark which closing CPP directive (#endif) pairs with which >> opening CPP directive (#if or #ifdef or #ifndef), make use of comments. >> ex: >> #ifdef <some-macro> /* To test/verify/enable xyz */ >> ..... >> .... >> #endif /* To test/verify/enable xyz */ >> >> There's a rule like this in the FreeBSD > Yes, and when I ported APIs, last year, as a part of my Project, the ported headers follow same rule. > and we follow it in RTEMS-libbsd. > It is nicely explained in the FreeBSD style guide so I'm pasting an excerpt > below: > Thanks! --Vaibhav Gupta > > " > The comment for #endif should match the expression used in the corre- > sponding #if or #ifdef. The comment for #else and #elif should match > the > inverse of the expression(s) used in the preceding #if and/or #elif > statements. In the comments, the subexpression "defined(FOO)" is > abbre- > viated as "FOO". For the purposes of comments, "#ifndef FOO" is > treated > as "#if !defined(FOO)". > > #ifdef KTRACE > #include <sys/ktrace.h> > #endif > > #ifdef COMPAT_43 > /* A large region here, or other conditional code. */ > #else /* !COMPAT_43 */ > /* Or here. */ > #endif /* COMPAT_43 */ > > #ifndef COMPAT_43 > /* Yet another large region here, or other conditional code. */ > #else /* COMPAT_43 */ > /* Or here. */ > #endif /* !COMPAT_43 */ > > " > > It would be nice to have a rule like this for RTEMS codes as well. > > > --Vaibhav Gupta >> _______________________________________________ >> devel mailing list >> devel@rtems.org >> http://lists.rtems.org/mailman/listinfo/devel >> >
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