Re: Coding Style Question - Is there any sane reason for doing this?

From	BCFD36 <bcfd36@cruzio.com>
Newsgroups	comp.lang.c++
Subject	Re: Coding Style Question - Is there any sane reason for doing this?
Date	2012-01-09 23:11 -0800
Organization	Aioe.org NNTP Server
Message-ID	<jegoav$5te$1@speranza.aioe.org> (permalink)
References	<40a2328f-2cd8-4dc6-a0e5-4894187042ce@q8g2000yqa.googlegroups.com> <9n1ilhFad4U2@mid.individual.net> <jegihu$ri7$1@speranza.aioe.org> <Xns9FD65BD51F41Amyfirstnameosapriee@216.196.109.131>

Show all headers | View raw

On 1/9/12 11:01 PM, Paavo Helde wrote:
> BCFD36<bcfd36@cruzio.com>  wrote in news:jegihu$ri7$1@speranza.aioe.org:
>
>> On 1/9/12 5:30 PM, Ian Collins wrote:
>>> On 01/10/12 02:11 PM, BCFD36 wrote:
>>>> I am working on a piece of legacy code that has many, shall we say,
>>>> strange things. This one, as J.K. Anderson (classics Prof at UC
>>>> Berkeley) used to say, "baffles me". It has the following statement
> in
>>>> the code:
>>>>
>>>> const unsigned int WAKEUP_MASK = (1<<  1) ;
>>>>
>>>> Is there any reason for doing this, other than to make the code even
>>>> more obscure?
>>>
>>> In addition to Alf's comments, the form is quite common especially in
>>> the embedded or driver world. Although it is more common to see
>>> something like
>>>
>>> const unsigned wakeupBit = 1;
>>> const unsigned someOtherBit = 2;
>>>
>>> // other bit definitions
>>>
>>> const uint32_t wakeupMask = (1u<<  wakeupBit);
>>>
>>
>> Interesting. I didn't know the form is common. I've never seen it
>> before, but I don't do much driver work and haven't seen it in the
>> embedded work I have done.
>>
>> Personally, I find it quite obscure and prefer the 0x0002 notation
>> myself. But I will have to think on it some more. I can see how you
>> could OR together a bunch of these and it be pretty clear which bits
> are
>> set. But I still find it obscure.
>
> The "1<<..." style is better for several reasons, most of which kick in
> when you have larger values than just 0x2:
>
>    - it clearly documents this is a bit mask
>    - it clearly documents there is only one bit set
>    - it clearly documents which bit it is so one can easily avoid
> collisions with other masks and see which bits are unused
>
> The hexadecimal notation can also do all these things, but requires more
> mental effort from the reader and familiarity with the hexadecimal
> notation in the first place.
>
> Cheers
> Paavo
>
>

Only two small quibbles... it was not at all clear to me what this was 
supposed to indicate. Now that I know the secret handshake, it makes 
more sense. And doing it in HEX is no problem at all, at least for me. 
Maybe it is the dinosaur in me.


-- 
Dave Scruggs

Thread

Coding Style Question - Is there any sane reason for doing this? BCFD36 <bcfd36@aol.com> - 2012-01-09 17:11 -0800
  Re: Coding Style Question - Is there any sane reason for doing this? "Alf P. Steinbach" <alf.p.steinbach+usenet@gmail.com> - 2012-01-10 02:23 +0100
    Re: Coding Style Question - Is there any sane reason for doing this? legalize+jeeves@mail.xmission.com (Richard) - 2012-01-10 06:05 +0000
      Re: Coding Style Question - Is there any sane reason for doing this? "Alf P. Steinbach" <alf.p.steinbach+usenet@gmail.com> - 2012-01-10 07:12 +0100
        Re: Coding Style Question - Is there any sane reason for doing this? BCFD36 <bcfd36@cruzio.com> - 2012-01-09 22:35 -0800
      Re: Coding Style Question - Is there any sane reason for doing this? Gareth Owen <gwowen@gmail.com> - 2012-01-10 06:58 +0000
    Re: Coding Style Question - Is there any sane reason for doing this? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-01-10 21:58 +0000
      Re: Coding Style Question - Is there any sane reason for doing this? David Dyer-Bennet <dd-b@dd-b.net> - 2012-01-10 16:46 -0600
      Re: Coding Style Question - Is there any sane reason for doing this? jt@toerring.de (Jens Thoms Toerring) - 2012-01-10 23:41 +0000
        Re: Coding Style Question - Is there any sane reason for doing this? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-01-11 00:19 +0000
          Re: Coding Style Question - Is there any sane reason for doing this? "MikeWhy" <boat042-nospam@yahoo.com> - 2012-01-10 21:53 -0600
      Re: Coding Style Question - Is there any sane reason for doing this? Juha Nieminen <nospam@thanks.invalid> - 2012-01-11 15:14 +0000
        Re: Coding Style Question - Is there any sane reason for doing this? Victor Bazarov <v.bazarov@comcast.invalid> - 2012-01-11 11:46 -0500
  Re: Coding Style Question - Is there any sane reason for doing this? Ian Collins <ian-news@hotmail.com> - 2012-01-10 14:30 +1300
    Re: Coding Style Question - Is there any sane reason for doing this? BCFD36 <bcfd36@cruzio.com> - 2012-01-09 21:32 -0800
      Re: Coding Style Question - Is there any sane reason for doing this? Paavo Helde <myfirstname@osa.pri.ee> - 2012-01-10 01:01 -0600
        Re: Coding Style Question - Is there any sane reason for doing this? BCFD36 <bcfd36@cruzio.com> - 2012-01-09 23:11 -0800
          Re: Coding Style Question - Is there any sane reason for doing this? yatremblay@bel1lin202.(none) (Yannick Tremblay) - 2012-01-11 10:23 +0000
            Re: Coding Style Question - Is there any sane reason for doing this? yatremblay@bel1lin202.(none) (Yannick Tremblay) - 2012-01-11 10:37 +0000
        Re: Coding Style Question - Is there any sane reason for doing this? Nick Keighley <nick_keighley_nospam@hotmail.com> - 2012-01-10 00:30 -0800
          Re: Coding Style Question - Is there any sane reason for doing this? "Alf P. Steinbach" <alf.p.steinbach+usenet@gmail.com> - 2012-01-10 16:31 +0100
            Re: Coding Style Question - Is there any sane reason for doing this? scott@slp53.sl.home (Scott Lurndal) - 2012-01-10 17:14 +0000
              Re: Coding Style Question - Is there any sane reason for doing this? Victor Bazarov <v.bazarov@comcast.invalid> - 2012-01-10 15:11 -0500
                Re: Coding Style Question - Is there any sane reason for doing this? Richard <rgrdev_@gmail.com> - 2012-01-10 21:45 +0100
                Re: Coding Style Question - Is there any sane reason for doing this? hanukas <jukka@liimatta.org> - 2012-01-11 00:04 -0800
                Re: Coding Style Question - Is there any sane reason for doing this? hanukas <jukka@liimatta.org> - 2012-01-11 00:15 -0800
                Re: Coding Style Question - Is there any sane reason for doing this? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-01-10 21:51 +0000
                Re: Coding Style Question - Is there any sane reason for doing this? "Bill Davy" <Bill@SynectixLtd.com> - 2012-01-11 08:30 +0000
                Re: Coding Style Question - Is there any sane reason for doing this? "Fred Zwarts \(KVI\)" <F.Zwarts@KVI.nl> - 2012-01-11 09:40 +0100
                Re: Coding Style Question - Is there any sane reason for doing this? hanukas <jukka@liimatta.org> - 2012-01-11 06:50 -0800
                Re: Coding Style Question - Is there any sane reason for doing this? scott@slp53.sl.home (Scott Lurndal) - 2012-01-11 17:28 +0000
                Re: Coding Style Question - Is there any sane reason for doing this? David Dyer-Bennet <dd-b@dd-b.net> - 2012-01-11 13:28 -0600
            Re: Coding Style Question - Is there any sane reason for doing this? jgk@panix.com (Joe keane) - 2012-01-11 17:51 +0000
            Re: Coding Style Question - Is there any sane reason for doing this? Nick Keighley <nick_keighley_nospam@hotmail.com> - 2012-01-12 05:40 -0800
              Re: Coding Style Question - Is there any sane reason for doing this? BCFD36 <bcfd36@cruzio.com> - 2012-01-12 20:42 -0800
          Re: Coding Style Question - Is there any sane reason for doing this? hanukas <jukka@liimatta.org> - 2012-01-10 23:50 -0800

csiph-web