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 10.236.90.67 with SMTP id d43mr41638673yhf.36.1381875588541;
 Tue, 15 Oct 2013 15:19:48 -0700 (PDT)
X-Received: by 10.50.83.6 with SMTP id m6mr122674igy.1.1381875588501; Tue, 15
 Oct 2013 15:19:48 -0700 (PDT)
Path: 
 border1.nntp.ams3.giganews.com!border1.nntp.ams2.giganews.com!border3.nntp.ams.giganews.com!backlog3.nntp.ams.giganews.com!border1.nntp.ams.giganews.com!nntp.giganews.com!feeder1.cambriumusenet.nl!feed.tweaknews.nl!209.85.216.87.MISMATCH!o2no7080641qas.0!news-out.google.com!9ni40949qaf.0!nntp.google.com!o2no7080639qas.0!postnews.google.com!glegroupsg2000goo.googlegroups.com!not-for-mail
Newsgroups: comp.lang.ada
Date: Tue, 15 Oct 2013 15:19:47 -0700 (PDT)
In-Reply-To: <9ee842b6-b053-4f4e-94df-66459ec1fb7c@googlegroups.com>
Complaints-To: groups-abuse@google.com
Injection-Info: glegroupsg2000goo.googlegroups.com;
 posting-host=97.123.228.141;
 posting-account=lJ3JNwoAAAAQfH3VV9vttJLkThaxtTfC
NNTP-Posting-Host: 97.123.228.141
References: <e87e8a92-9822-4764-a4a6-1fbc6715ef52@googlegroups.com>
 <l3kab9$qbv$1@dont-email.me>
 <9ee842b6-b053-4f4e-94df-66459ec1fb7c@googlegroups.com>
User-Agent: G2/1.0
MIME-Version: 1.0
Message-ID: <6d603161-46a4-4d3a-a5b9-0babb9887619@googlegroups.com>
Subject: Re: Passing a String to a C/C++ Subprogram (Special Case)
From: Shark8 <onewingedshark@gmail.com>
Injection-Date: Tue, 15 Oct 2013 22:19:48 +0000
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable
X-Original-Bytes: 3511
Xref: number.nntp.dca.giganews.com comp.lang.ada:183627
Date: 2013-10-15T15:19:47-07:00
List-Id: <comp.lang.ada>

On Tuesday, October 15, 2013 3:13:09 PM UTC-6, Eryndlia Mavourneen wrote:
> On Tuesday, October 15, 2013 3:59:21 PM UTC-5, Jeffrey Carter wrote:
>=20
> > On 10/15/2013 12:54 PM, Eryndlia Mavourneen wrote:
>=20
> >=20
>=20
> > >  . . .
>=20
> >=20
>=20
> > If I were doing this, I would wrap each in an Ada subprogram that ensur=
es the=20
>=20
> > String will be passed correctly to C. Ultimately it will be less effort=
.
>=20
> >=20
>=20
>=20
>=20
> Thanks, Jeff.  This could be a good way to manage things.  Unfortunately,=
 I can not guarantee that I can perform a trim operation or that the last c=
haracter is indeed not being used (for the placement of a nul).  I suppose =
I could create the wrapper, as you said, and copy the String (1 .. size) to=
 a String (1 .. size + 1) and place a nul in the last character of the targ=
et string.  Of course, this does not add a lot of overhead for short string=
s, but it is a hard real-time system.
>=20
>=20
>=20
> It sounds as if I need to get with my people and get a further, clear con=
sensus about how this stuff is going to be used, in reality.
>=20
>=20
>=20
> -- Eryndlia Mavourneen (KK1T)

Could you use an Ada 2012 subtype predicate? something like:

    Type Transport_String is array (1..31) of Character
        with Default_Component_Value =3D> ASCII.NUL,
        Dynamic_Predicate =3D> Transport_String(Transport_String'Last) =3D =
ASCII.NUL;

Actually I'm rather disappointed that there aren't static_predicates availa=
ble for Arrays. I had hoped to, in my OpenGL binding, have something like t=
he following available for the vector operations:

    Type RGBA is (Red, Blue, Green, Alpha);=20
    Subtype RGB is RGBA range Red..Blue;
   =20
    --  Declare the general Vector-type for OprnGL which has vectors
    --  of three or four components of RGBA [A being optional], always
    --  starting with R.
    Type Float_Vector is array(RGBA range <>) of Float
        with Static_Predicate =3D> Float_Vector'First =3D Red;