From: ron@ronnatalie.com
To: "Jon Steinhart" <jon@fourwinds.com>
Cc: tuhs@tuhs.org
Subject: [TUHS] #defines and enums
Date: Wed, 13 Nov 2019 14:15:14 -0500 [thread overview]
Message-ID: <055e389cb6a223888c86228963327efc.squirrel@squirrelmail.tuffmail.net> (raw)
In-Reply-To: <201911131802.xADI2fxE752068@darkstar.fourwinds.com>
>
> BTW, I'm doing my first messing around with the Linux kernel these days;
> if anyone knows the guts of the generic filesystem code I could use a bit
> of help. Here's something that I came across on the way in <sys/mount.h>:
>
> enum
> {
> MS_RDONLY = 1, /* Mount read-only. */
> #define MS_RDONLY MS_RDONLY
> MS_NOSUID = 2, /* Ignore suid and sgid bits. */
> #define MS_NOSUID MS_NOSUID
> MS_NODEV = 4, /* Disallow access to device special files. */
> #define MS_NODEV MS_NODEV
> ...
> };
>
> Can anyone explain the value of this programming style? Is this just an
> example of the result of how programming is taught today?
>
>
This really is more a C question than a UNIX one. The problem is that
the preprocessor macros are really kind of a kludge. Making things
either enums (or in later C/C++ const int definitions) is a lot cleaner.
The #define is just probably backwards a compatibility kludge (for people
using things like MS_RDONLY or whatever in other macros).
next prev parent reply other threads:[~2019-11-13 19:15 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-12 20:56 [TUHS] Happy birthday Morris worm Norman Wilson
2019-11-12 22:00 ` Dave Horsfall
2019-11-12 22:10 ` [TUHS] buffer overflow (Re: " Bakul Shah
2019-11-12 22:14 ` Larry McVoy
2019-11-12 22:41 ` Robert Clausecker
2019-11-12 22:49 ` Arthur Krewat
2019-11-12 23:45 ` Jon Steinhart
2019-11-13 0:38 ` Warren Toomey
2019-11-13 1:09 ` Arthur Krewat
2019-11-13 0:24 ` Larry McVoy
2019-11-12 22:54 ` Dave Horsfall
2019-11-12 23:22 ` Warner Losh
2019-11-12 23:27 ` Arthur Krewat
[not found] ` <alpine.DEB.2.20.1911191443530.10845@grey.csi.cam.ac.uk>
2019-11-21 20:02 ` Dave Horsfall
2019-11-21 20:38 ` Warner Losh
2019-11-21 21:04 ` Clem Cole
2019-11-21 22:06 ` Dave Horsfall
2019-11-21 21:48 ` Steffen Nurpmeso
2019-11-13 7:35 ` [TUHS] " arnold
2019-11-13 18:02 ` [TUHS] Happy birthday Morris worm [ really programming education ] Jon Steinhart
2019-11-13 18:49 ` Tyler Adams
2019-11-13 19:15 ` ron [this message]
2019-11-13 21:11 ` [TUHS] #defines and enums Warner Losh
2019-11-13 21:22 ` [TUHS] Happy birthday Morris worm [ really programming education ] Chet Ramey
2019-11-15 22:49 ` Adam Thornton
2019-11-15 23:59 ` Theodore Y. Ts'o
2019-11-14 1:35 [TUHS] #defines and enums Larry McVoy
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