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,e9184f90d0749b32
X-Google-Attributes: gid103376,public
From: bobduff@world.std.com (Robert A Duff)
Subject: Re: Using a procedure as a parameter (Gnat)
Date: 1996/03/27
Message-ID: <DowMnK.K6F@world.std.com>#1/1
X-Deja-AN: 144403430
references: <4ja0da$442@newsflash.concordia.ca>
organization: The World Public Access UNIX, Brookline, MA
newsgroups: comp.lang.ada
Date: 1996-03-27T00:00:00+00:00
List-Id: <comp.lang.ada>

In article <4ja0da$442@newsflash.concordia.ca>,
Chris O'Regan <chris@ECE.Concordia.CA> wrote:
>ack.adb:11:35: subprogram must not be deeper than access type

Deeper means more deeply nested within subprograms (packages don't
count).  In your case, you can easily move the procedure into a package,
since it doesn't reference any local variables in the next-outer
procedure.  So put P in a library package, and all will be well.

Sometimes, the procedure you want to pass wants to reference variables
in the next-outer procedure.  In that case, you can use GNAT's
'Unrestricted_Access.  But beware: (1) it's not a standard feature, and
(2) it can cause dangling pointers if you're not careful.  A better
alternative might be to use a generic formal subprogram.

- Bob