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,FREEMAIL_FROM
	autolearn=unavailable autolearn_force=no version=3.4.4
X-Received: by 2002:a37:aa45:: with SMTP id
 t66mr15885010qke.218.1575666340633;
        Fri, 06 Dec 2019 13:05:40 -0800 (PST)
X-Received: by 2002:a9d:eee:: with SMTP id 101mr3011262otj.5.1575666340404;
 Fri, 06 Dec 2019 13:05:40 -0800 (PST)
Path: 
 eternal-september.org!reader01.eternal-september.org!feeder.eternal-september.org!news.gegeweb.eu!gegeweb.org!fdn.fr!proxad.net!feeder1-2.proxad.net!209.85.160.216.MISMATCH!g89no888318qtd.0!news-out.google.com!w29ni312qtc.0!nntp.google.com!g89no888310qtd.0!postnews.google.com!glegroupsg2000goo.googlegroups.com!not-for-mail
Newsgroups: comp.lang.ada
Date: Fri, 6 Dec 2019 13:05:40 -0800 (PST)
In-Reply-To: <qsedo3$chm$1@dont-email.me>
Complaints-To: groups-abuse@google.com
Injection-Info: glegroupsg2000goo.googlegroups.com; posting-host=146.5.2.231;
 posting-account=lJ3JNwoAAAAQfH3VV9vttJLkThaxtTfC
NNTP-Posting-Host: 146.5.2.231
References: <87muca3vgd.fsf@nightsong.com>
 <57d49047-0a61-4d13-8822-d004732a3acc@googlegroups.com>
 <d2f6474f-2534-463f-b075-9550ce8931da@googlegroups.com>
 <qs5ngj$tah$1@dont-email.me>
 <a6e6220c-1cf1-4ee7-9ee6-e8dc1b7a5a28@googlegroups.com>
 <3b1b248b-43d0-4762-b1f5-1c5460d24c8b@googlegroups.com>
 <5e222e6c-7afe-4349-ac66-d9b78ca40ec6@googlegroups.com>
 <27b11294-d628-4118-8328-a4a9a3946937@googlegroups.com>
 <be3b770c-9e58-4af0-bf69-c97de02eecc5@googlegroups.com>
 <80bcdfd1-b1e5-4ebf-aa8a-4beaba5ec3c2@googlegroups.com>
 <60e61003-409d-4bd5-9784-8ddad5942934@googlegroups.com>
 <4f659af6-c840-4509-9f76-e9a96b547a55@googlegroups.com>
 <qsbble$nen$1@news.albasani.net>
 <d9f17ae0-4f0c-4fcb-a068-6429b768ba7a@googlegroups.com>
 <qsedo3$chm$1@dont-email.me>
User-Agent: G2/1.0
MIME-Version: 1.0
Message-ID: <b08cad8b-eea0-435d-8058-19321affe42c@googlegroups.com>
Subject: Re: Beginning Ada Programming, by Andrew T. Shvets (2020)
From: Shark8 <onewingedshark@gmail.com>
Injection-Date: Fri, 06 Dec 2019 21:05:40 +0000
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Xref: reader01.eternal-september.org comp.lang.ada:57677
Date: 2019-12-06T13:05:40-08:00
List-Id: <comp.lang.ada>

On Friday, December 6, 2019 at 1:29:57 PM UTC-7, Jeffrey R. Carter wrote:
> On 12/6/19 7:34 PM, Shark8 wrote:
> >>>
> >>> Type Password is new String
> >>>     with Dynamic_Predicate =3D> Password'Length in Minimum_Length..Ma=
ximum_Length
> >>>       and (For all C of Password =3D> C in Digit|Upper_Case|Lower_Cas=
e|Symbol)
> >>>       and Password(Password'First) Lower_Case;
>=20
> It looks like you left out an "in".
>=20
> I bet the coders among us are having heart attacks about the "inefficienc=
y" of=20
> checking the first character twice. I'd be interested in hearing from com=
piler=20
> writers whether their optimizers would optimize that.
Why?
Seriously, why worry about inefficiency at this level? Almost all your obse=
rvable problems are going to be algorithmic, and attaching assertions to a =
type allows for optimizations.

Example:
Function Copy( Object : Password ) return Password is (Object);
We know that passing in parameter object, the item must be conformant to Pa=
ssword [checked on call) and so can copy and pass out the Password without =
checking its validity... MORE, given a variable X --X : Password:=3D Create=
_Password("ThisPassword#1!")-- we know that X must conform to the definitio=
n, so then Y : Password:=3D Copy( X ); needn't make any check at all.