From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me
X-Spam-Level: 
X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00 autolearn=ham
	autolearn_force=no version=3.4.4
X-Google-Thread: 103376,36b302576d78847a
X-Google-Attributes: gid103376,public
X-Google-Language: ENGLISH,ASCII-7-bit
Path: 
 g2news2.google.com!news4.google.com!border1.nntp.dca.giganews.com!border2.nntp.dca.giganews.com!nntp.giganews.com!atl-c08.usenetserver.com!news.usenetserver.com!pc03.usenetserver.com!news.flashnewsgroups.com-b7.4zTQh5tI3A!not-for-mail
Newsgroups: comp.lang.ada
Subject: Re: How do you bitwise operations in Ada '83 and '95
References: <mailman.41.1153420245.30988.comp.lang.ada@ada-france.org>
 <xMqdnQjpNPbQRiLZnZ2dnUVZ_tqdnZ2d@comcast.com>
  <m2k668gc81.fsf@grendel.local> <umzb3p8ym.fsf@acm.org>
  <m2bqrihj0j.fsf@grendel.local>
From: Stephen Leake <stephen_leake@acm.org>
Date: Sun, 23 Jul 2006 11:59:43 -0400
Message-ID: <uwta448i8.fsf@acm.org>
User-Agent: Gnus/5.1006 (Gnus v5.10.6) Emacs/21.3 (windows-nt)
Cancel-Lock: sha1:K/2FQDgEWe1WxXw7xmpop+YrY+o=
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
X-Complaints-To: abuse@flashnewsgroups.com
Organization: FlashNewsgroups.com
X-Trace: 0fd1e44c39cf0e084460632120
Xref: g2news2.google.com comp.lang.ada:5888
Date: 2006-07-23T11:59:43-04:00
List-Id: <comp.lang.ada>

Simon Wright <simon@pushface.org> writes:

> Stephen Leake <stephen_leake@acm.org> writes, responding to me:
>
>>> I have a feeling that shift&mask ends up more understandable 
>>
>> Never.
>>
>>> and reviewable.
>>
>> In Ada 95, maybe. In Ada 2005, not.
>
> Really, understandable and reviewable are very similar, so I don't see
> how something could be (possibly) more reviewable while never more
> understandable.

Hmm. To me, "understandable" means "expressed in terms I am familiar
with, using idioms I am familiar with, and unambiguous". Or something
like that.

While "reviewable" means "traceable to source documentation".

So if I am familiar with the Ada 95 idiom for endianness-independent
rep clauses, they are "understandable". But because they are complex,
they may be less reviewable. I've never done a _formal_ review (trace to
source docs) of any software, so I'm on shaky ground here.

> Seriously, the C
>
>   field = (longword >> 15) & 0x3f;
>
> is pretty clear.

At the bit level, yes. But if the 7 bits are supposed to represent
some object, actual names would be far preferable.

-- 
-- Stephe