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=-1.3 required=5.0 tests=BAYES_00,INVALID_MSGID
	autolearn=no autolearn_force=no version=3.4.4
X-Google-Language: ENGLISH,ASCII-7-bit
X-Google-Thread: 103376,ef6c792702c0ff46
X-Google-Attributes: gid103376,public
From: Al Johnston <sofeise@mindspring.com>
Subject: Re: ada to c interfaces and CHARS_PTR
Date: 2000/03/15
Message-ID: <38CF1BC2.40A39D26@mindspring.com>#1/1
X-Deja-AN: 597665270
Content-Transfer-Encoding: 7bit
References: <38C7E515.29C42580@mindspring.com>
 <slrn8cg0rv.mlp.gisle@spurv.ii.uib.no> <38C81310.41EB934A@mindspring.com>
 <8ajfsc$9a6$1@nnrp1.deja.com>
X-Accept-Language: en
X-Server-Date: 15 Mar 2000 05:14:38 GMT
Content-Type: text/plain; charset=us-ascii
Organization: MindSpring Enterprises
Mime-Version: 1.0
Newsgroups: comp.lang.ada
Date: 2000-03-15T05:14:38+00:00
List-Id: <comp.lang.ada>

> > > C has not 'in out' parameters, only 'in' parameters. To pass
> the
> >
> > ???? Although I am still trying to figure this stuff out, it
> seems to
> > me that c as as much of an in/out as any other language has.
>
> No, this is completely wrong, there is a very important semantic
> difference between passing a parameter as IN OUT (which in Ada

after spend a day trying to get from a STRING to a chars_ptr using
a chain function calls (without calling an allocator routine) I find
that
I am in no position to defined any of my understandings of anything.
It has been a bad day.

Yes, I guess there is a big deference between c's by value and ada's
mode in/out/inout modes.  I am just so used to viewing everything
in c as pass by value... if i need to pass a string in c, what really
gets passed is the "value" of the c's address (char *)... or maybe the
"value" of the address where the subroutine is to write the address
of the string (char **).

The ada code I inherited uses " foo : in system.address" as formal
parameters for all of its calls to c.  Because of this, I am not used
to thinking about ada passing/returning an array or record by
value... but instead it (ada) returns the "value" of the address
of the array or structure. This view is incredibly limited, and
I know it.  If I learned ada from supporting better code, maybe
I wouldn't have such weird understandings.

I tend to vies everything in terms of c's by value model.  I think
I better stop this habit QUICKLY.

If you wish to suggest any books in particular, I will make and effort
to get and read them.. I have spent a lot of time in cohen's book,
in the RM and Rat.

-al