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,LOTS_OF_MONEY
	autolearn=ham autolearn_force=no version=3.4.4
X-Google-Language: ENGLISH,ASCII-7-bit
X-Google-Thread: 103376,9e02dc5f2c4718ab
X-Google-Attributes: gid103376,public
X-Google-ArrivalTime: 2002-11-18 07:29:53 PST
Path: archiver1.google.com!postnews1.google.com!not-for-mail
From: dennison@telepath.com (Ted Dennison)
Newsgroups: comp.lang.ada
Subject: Re: Novice help with types and de-allocation.
Date: 18 Nov 2002 07:29:53 -0800
Organization: http://groups.google.com/
Message-ID: <4519e058.0211180729.10b630dc@posting.google.com>
References: <sX%B9.65239$NH2.4291@sccrnsc01>
NNTP-Posting-Host: 65.115.221.98
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 8bit
X-Trace: posting.google.com 1037633393 18046 127.0.0.1 (18 Nov 2002 15:29:53
 GMT)
X-Complaints-To: groups-abuse@google.com
NNTP-Posting-Date: 18 Nov 2002 15:29:53 GMT
Xref: archiver1.google.com comp.lang.ada:31046
Date: 2002-11-18T15:29:53+00:00
List-Id: <comp.lang.ada>

Stapler <spam.magnet@yahoo.com> wrote in message news:<sX%B9.65239$NH2.4291@sccrnsc01>...
> Alright, I have a package which more or less works but I'm having trouble
> in a couple spots. I've placed comments where I'm having trouble.

> 	type Buff_Out is array(Positive range <>) of Integer;
...
> 	type Int_Buffer is array(1..Size) of Integer;
...
> 	function Read_Buff(Y : in Int_Buffer; Read_Length : in Natural; Loc : in Natural) return Buff_Out is
> 	
> 		Ret_Buff : Buff_Out(1..Read_Length);
> 	begin
> 		-- For some reason, the compiler expects Y to be of type Buff_Out.
> 		-- Do I need to use Unchecked_Conversion here?
> 		Ret_Buff := Y(Loc .. Read_Length - 1);

The "some reason" is that the object you are assigning Y into is of
that type. Unlike some other languages, in Ada you can't assign
objects of one type into objects of a another type, just because both
types have similar contents. You defined Int_Buffer and Buff_Out to be
different types, so they are truly considered unrelated types.

Probably the best way out would be to make Int_Buffer a *subtype* of
Buff_Out, instead of a type in its own right. If you don't like that
solution, then the next best thing would be to make the private
definition of "Int_Buffer" a "new Buff_Out". That would allow you to
use a simple type conversion.

Do *not* used Unchecked_Conversion for this. Unchecked_Conversion is
not for bailing yourself out of a badly-designed type system. Use it
for when you truly have multiple different ways of looking at the data
(eg: A complicated record that requires a CRC at the end, so it must
also be an array of unsigned bytes).