Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > comp.lang.c > #162904
| From | Bart <bc@freeuk.com> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: redeclaration of enumerators? |
| Date | 2021-10-01 15:38 +0100 |
| Organization | A noiseless patient Spider |
| Message-ID | <sj76ho$io$1@dont-email.me> (permalink) |
| References | (10 earlier) <sj44gi$odk$1@dont-email.me> <bf3ac5ed-f44b-4f8d-9ffe-ad9583ade948n@googlegroups.com> <sj6csf$dvm$1@dont-email.me> <sj6nkg$4am$1@dont-email.me> <sj72lq$3f2$1@dont-email.me> |
On 01/10/2021 14:32, David Brown wrote:
> On 01/10/2021 12:24, Bart wrote:
>> On 01/10/2021 08:20, David Brown wrote:
>>> On 30/09/2021 16:36, Malcolm McLean wrote:
>>>> On Thursday, 30 September 2021 at 11:45:50 UTC+1, David Brown wrote:
>>>>>
>>>>> But I think that in most cases, it is not at all helpful to think about
>>>>> the underlying integer values. You get cleaner, safer, more portable
>>>>> code if you treat the enumeration constants as being abstract symbols
>>>>> that are members of the particular type without any other semantics or
>>>>> meaning.
>>>>>
>>>> I agree, but there are some snags. One is if you wish to print out
>>>> the enum
>>>> for debug purposes. It's easy enough to write printf("light %d\n",
>>>> (int) lightenumval);
>>>> If you have to set up an enum to string function then it's a bit
>>>> clearer, but it's a huge
>>>> hassle for debug.
>>>> The other snag is that often you want to use the enum to index into a
>>>> table
>>>> of some sort. Again, you can set up a system by writing a switch, but
>>>> that's
>>>> likely slower and more code.
>>>>
>>>
>>> These are not "snags" - they are cases where the underlying integer
>>> value of the enumeration constants is sometimes helpful due to the
>>> limitations of the language. Eventually, C++ will get some decent
>>> compile-time reflection capabilities that will allow you to generate
>>> strings from enumeration constants simply and easily, without repetition
>>> in the code (and without complicated X-macros).
>>>
>>> In the meantime, C99, and C++ with gcc extensions (unfortunately not
>>> standard), let you write:
>>>
>>>
>>> typedef enum Colours { red, green, blue } Colours;
>>>
>>> extern const char * const colour_names[];
>>> const char * const colour_names[] = {
>>> [red] = "red",
>>> [green] = "green",
>>> [blue] = "blue",
>>> };
>>
>> This is not ideal:
>>
> Obviously it is not ideal - that was clearly implied by what I wrote.
> And we don't need a list of the weaknesses here,
Why not? I listed most of the problems, which may not have been
apparently to everyone since your example was written perfectly, and
showed how I get around most of those with a unique approach of mine, a
feature I now find invaluable.
I'm not making a proposal for C; it's an idea that someone else could
pick up on and maybe suggest or implement something better than those
ghastly X-macros.
You're welcome.
Back to comp.lang.c | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
redeclaration of enumerators? Thiago Adams <thiago.adams@gmail.com> - 2021-09-27 10:39 -0700
Re: redeclaration of enumerators? John Bode <jfbode1029@gmail.com> - 2021-09-28 16:21 -0500
Re: redeclaration of enumerators? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-09-28 14:57 -0700
Re: redeclaration of enumerators? Thiago Adams <thiago.adams@gmail.com> - 2021-09-28 15:23 -0700
Re: redeclaration of enumerators? David Brown <david.brown@hesbynett.no> - 2021-09-29 15:23 +0200
Re: redeclaration of enumerators? Mark Bluemel <mark.bluemel@gmail.com> - 2021-09-30 01:15 -0700
Re: redeclaration of enumerators? Bart <bc@freeuk.com> - 2021-09-28 23:31 +0100
Re: redeclaration of enumerators? David Brown <david.brown@hesbynett.no> - 2021-09-29 15:36 +0200
Re: redeclaration of enumerators? Bart <bc@freeuk.com> - 2021-09-29 15:03 +0100
Re: redeclaration of enumerators? David Brown <david.brown@hesbynett.no> - 2021-09-29 16:46 +0200
Re: redeclaration of enumerators? Bart <bc@freeuk.com> - 2021-09-29 16:08 +0100
Re: redeclaration of enumerators? David Brown <david.brown@hesbynett.no> - 2021-09-29 20:14 +0200
Re: redeclaration of enumerators? Thiago Adams <thiago.adams@gmail.com> - 2021-09-29 13:37 -0700
Re: redeclaration of enumerators? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-09-29 18:25 -0700
Re: redeclaration of enumerators? David Brown <david.brown@hesbynett.no> - 2021-09-30 12:45 +0200
Re: redeclaration of enumerators? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2021-09-30 07:36 -0700
Re: redeclaration of enumerators? David Brown <david.brown@hesbynett.no> - 2021-10-01 09:20 +0200
Re: redeclaration of enumerators? Bart <bc@freeuk.com> - 2021-10-01 11:24 +0100
Re: redeclaration of enumerators? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2021-10-01 04:49 -0700
Re: redeclaration of enumerators? Bart <bc@freeuk.com> - 2021-10-01 13:06 +0100
Re: redeclaration of enumerators? Tony Oliver <guinness.tony@gmail.com> - 2021-10-01 05:24 -0700
Re: redeclaration of enumerators? Bart <bc@freeuk.com> - 2021-10-01 13:32 +0100
Re: redeclaration of enumerators? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2021-10-01 05:32 -0700
Re: redeclaration of enumerators? Bart <bc@freeuk.com> - 2021-10-01 13:43 +0100
Re: redeclaration of enumerators? Mark Bluemel <mark.bluemel@gmail.com> - 2021-10-01 06:13 -0700
Re: redeclaration of enumerators? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2021-10-01 06:29 -0700
Re: redeclaration of enumerators? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-10-01 15:30 +0100
Re: redeclaration of enumerators? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2021-10-01 08:28 -0700
Re: redeclaration of enumerators? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-10-01 17:08 +0100
Re: redeclaration of enumerators? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2021-10-01 15:12 -0700
Re: redeclaration of enumerators? David Brown <david.brown@hesbynett.no> - 2021-10-01 15:37 +0200
Re: redeclaration of enumerators? Bart <bc@freeuk.com> - 2021-10-01 15:30 +0100
Re: redeclaration of enumerators? David Brown <david.brown@hesbynett.no> - 2021-10-01 19:12 +0200
Re: redeclaration of enumerators? Bart <bc@freeuk.com> - 2021-10-01 19:06 +0100
Re: redeclaration of enumerators? David Brown <david.brown@hesbynett.no> - 2021-10-01 15:32 +0200
Re: redeclaration of enumerators? Bart <bc@freeuk.com> - 2021-10-01 15:38 +0100
Re: redeclaration of enumerators? Bart <bc@freeuk.com> - 2021-10-01 17:40 +0100
Re: redeclaration of enumerators? Bart <bc@freeuk.com> - 2021-10-02 12:16 +0100
Re: redeclaration of enumerators? David Brown <david.brown@hesbynett.no> - 2021-10-02 15:34 +0200
Re: redeclaration of enumerators? Bart <bc@freeuk.com> - 2021-10-02 15:16 +0100
Re: redeclaration of enumerators? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-10-01 13:58 -0700
Re: redeclaration of enumerators? Richard Damon <Richard@Damon-Family.org> - 2021-10-01 17:21 -0400
Re: redeclaration of enumerators? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2021-10-01 14:56 -0700
Re: redeclaration of enumerators? David Brown <david.brown@hesbynett.no> - 2021-10-02 12:21 +0200
Re: redeclaration of enumerators? scott@slp53.sl.home (Scott Lurndal) - 2021-09-30 14:47 +0000
Re: redeclaration of enumerators? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2021-09-30 10:10 -0700
Re: redeclaration of enumerators? David Brown <david.brown@hesbynett.no> - 2021-10-01 09:24 +0200
Re: redeclaration of enumerators? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2021-09-29 12:43 -0700
Re: redeclaration of enumerators? Branimir Maksimovic <branimir.maksimovic@gmail.com> - 2021-09-29 03:40 +0000
csiph-web