Re: Header files with enums instead of defines?

From: Garance A Drosihn (drosih_at_rpi.edu)
Date: 12/22/04

  • Next message: Jun Su: "Re: Propose for Several Dump types" 
    Date: Tue, 21 Dec 2004 21:06:32 -0500
To: "Greg 'groggy' Lehey" <grog@freebsd.org>, FreeBSD Architecture Mailing List <arch@freebsd.org>

    At 11:31 AM +1030 12/22/04, Greg 'groggy' Lehey wrote:
    >
    >To find out what that means, I need to go to
    >/usr/src/include/sys/errno.h and look for 17. I find:
    >
    >#define EEXIST 17 /* File exists */
    >
    >If we were to change this to
    >
    >enum EEXIST = 17; /* File exists */
    >
    >I'd then be able to see:
    >
    > xerrno = EEXIST,
    >
    >That makes debugging a whole lot easier. About the only down side
    >I can see is that you can't #undef an enum. Is this a big deal?

    You also can't #ifdef an enum.

    You also can't:
         enum EEXIST = 17;
    I'm not a C expert, but you need something more like:
         enum ERRVALS { EEXIST = 17 };
    At least that compiles for me.

    Some C compilers (irix) will also complain if you assign an
    enum-value (such as EEXIST) to a variable which isn't of the same
    enum-type (eg: ERRVALS). So, in those compilers you would have
    to define 'xerror' as 'enum ERRVALS xerror', not 'int xerror'.
    I think that isn't part of the C standard, but on occassion that
    check has found a few bugs for me... 

    -- 
Garance Alistair Drosehn            =   gad@gilead.netel.rpi.edu
Senior Systems Programmer           or  gad@freebsd.org
Rensselaer Polytechnic Institute    or  drosih@rpi.edu
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  • Next message: Jun Su: "Re: Propose for Several Dump types"

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