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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).



  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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