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| author | Alejandro Colomar <alx@kernel.org> | 2024-04-26 15:06:49 +0200 |
|---|---|---|
| committer | Alejandro Colomar <alx@kernel.org> | 2024-05-02 01:24:19 +0200 |
| commit | dcde2f70372b49ec43efc5db864c9ff585d0a2dd (patch) | |
| tree | 78b9b7425130e4a5858e4c01a524d802423879ed /man/man3/_Generic.3 | |
| parent | 12aca537ce78a41bbcdaf485209691e10f8002d7 (diff) | |
| download | man-pages-dcde2f70372b49ec43efc5db864c9ff585d0a2dd.tar.gz | |
man/, share/mk/: Move man*/ to man/
This is a scripted change:
$ mkdir man/;
$ mv man* man/;
$ ln -st . man/man*;
$ find share/mk/ -type f \
| xargs grep -l '^MANDIR *:=' \
| xargs sed -i '/^MANDIR *:=/s,$,/man,';
$ find share/mk/dist/ -type f \
| xargs grep -l man \
| xargs sed -i 's,man%,man/%,g';
Link: <https://lore.kernel.org/linux-man/YxcV4h+Xn7cd6+q2@pevik/T/>
Cc: Petr Vorel <pvorel@suse.cz>
Cc: Jakub Wilk <jwilk@jwilk.net>
Cc: Stefan Puiu <stefan.puiu@gmail.com>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
Diffstat (limited to 'man/man3/_Generic.3')
| -rw-r--r-- | man/man3/_Generic.3 | 64 |
1 files changed, 64 insertions, 0 deletions
diff --git a/man/man3/_Generic.3 b/man/man3/_Generic.3 new file mode 100644 index 0000000000..788a117ddf --- /dev/null +++ b/man/man3/_Generic.3 @@ -0,0 +1,64 @@ +.\" Copyright (C) 2022 Alejandro Colomar <alx@kernel.org> +.\" +.\" SPDX-License-Identifier: Linux-man-pages-copyleft +.\" +.TH _Generic 3 (date) "Linux man-pages (unreleased)" +.SH NAME +_Generic \- type-generic selection +.SH SYNOPSIS +.nf +.BR _Generic( \fIexpression\fP ", type1: " e1 ", " "... /*" \ +", default: " "e */" ); +.fi +.SH DESCRIPTION +.BR _Generic () +evaluates the path of code under the type selector +that is compatible with the type of the controlling +.IR expression , +or +.B default: +if no type is compatible. +.P +.I expression +is not evaluated. +.P +This is especially useful for writing type-generic macros, +that will behave differently depending on the type of the argument. +.SH STANDARDS +C11. +.SH HISTORY +C11. +.SH EXAMPLES +The following program demonstrates how to write +a replacement for the standard +.BR imaxabs (3) +function, which being a function can't really provide what it promises: +seamlessly upgrading to the widest available type. +.IP +.\" SRC BEGIN (_Generic.c) +.EX +#include <stdint.h> +#include <stdio.h> +#include <stdlib.h> +\& +#define my_imaxabs _Generic(INTMAX_C(0), \e + long: labs, \e + long long: llabs \e +/* long long long: lllabs */ \e +) +\& +int +main(void) +{ + off_t a; +\& + a = \-42; + printf("imaxabs(%jd) == %jd\en", (intmax_t) a, my_imaxabs(a)); + printf("&imaxabs == %p\en", &my_imaxabs); + printf("&labs == %p\en", &labs); + printf("&llabs == %p\en", &llabs); +\& + exit(EXIT_SUCCESS); +} +.EE +.\" SRC END |