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Relax the rule against declaring variables in nested scopes and for

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initializations.

Relax some overly perscriptive rules against declarations: they may be at the
start of any blocks, even if things aren't super complicated. Allow more
initializations (those that call simple functions, like accessor functions for
newbus are fine). Allow the common idiom of declaring the loop variable in a for
loop.

This tries to codify what common exceptions are today, as well as give
some guidance on when it's best to do these things.

Reviewed by: tsoome, kp, markm, allanjude, jiles, cem, rpokala
	(earlier versions: seanc, melifaro, bapt, pjd, bz, pstef, arichards,
	 jhibits, vangyzen, jmallet, ian, glebius, jhb, dab, adrian,
	 sef, gnn)
Differential Revision: https://reviews.freebsd.org/D25312
This commit is contained in:
Warner Losh 2020-07-16 14:12:54 +00:00
parent 3ea3fbe685
commit 34a8e7368f
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=363250
1 changed files with 21 additions and 13 deletions
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34
share/man/man9/style.9
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@ -25,7 +25,7 @@
.\" From: @(#)style 1.14 (Berkeley) 4/28/95
.\" $FreeBSD$
.\"
.Dd June 30, 2020
.Dd July 16, 2020
.Dt STYLE 9
.Os
.Sh NAME
@ -592,8 +592,6 @@ not
Parts of a
.Ic for
loop may be left empty.
Do not put declarations
inside blocks unless the routine is unusually complicated.
.Bd -literal
for (; cnt < 15; cnt++) {
stmt1;
@ -601,6 +599,15 @@ inside blocks unless the routine is unusually complicated.
}
.Ed
.Pp
A
.Ic for
loop may declare and initialize its counting variable.
.Bd -literal
for (int i = 0; i < 15; i++) {
stmt1;
}
.Ed
.Pp
Indentation is an 8 character tab.
Second level indents are four spaces.
If you have to wrap a long statement, put the operator at the end of the
@ -676,25 +683,26 @@ The opening brace of the function body should be
on a line by itself.
.Bd -literal
static char *
function(int a1, int a2, float fl, int a4)
function(int a1, int a2, float fl, int a4, struct bar *bar)
{
.Ed
.Pp
When declaring variables in functions declare them sorted by size,
then in alphabetical order; multiple ones per line are okay.
If a line overflows reuse the type keyword.
.Pp
Be careful to not obfuscate the code by initializing variables in
the declarations.
Use this feature only thoughtfully.
DO NOT use function calls in initializers.
Variables may be initialized where declared especially when they
are constant for the rest of the scope.
Declarations may be placed before executable lines at the start
of any block.
Calls to complicated functions should be avoided when initializing variables.
.Bd -literal
struct foo one, *two;
double three;
int *four, five;
char *six, seven, eight, nine, ten, eleven, twelve;
struct baz *three = bar_get_baz(bar);
double four;
int *five, six;
char *seven, eight, nine, ten, eleven, twelve;
four = myfunction();
four = my_complicated_function(a1, f1, a4);
.Ed
.Pp
Do not declare functions inside other functions; ANSI C says that