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,dabd2d2ffbcf1daa
X-Google-Attributes: gid103376,public
From: Robert Dewar <robert_dewar@my-deja.com>
Subject: Re: Exiting from a function or procedure
Date: 2000/04/24
Message-ID: <8e059m$3u$1@nnrp1.deja.com>#1/1
X-Deja-AN: 614796746
References: <8duvlj$opk$1@nnrp1.deja.com>
 <vzJM4.1253$t25.356170@news.pacbell.net>
X-Http-Proxy: 1.0 x43.deja.com:80 (Squid/1.1.22) for client 205.232.38.14
Organization: Deja.com - Before you buy.
X-Article-Creation-Date: Mon Apr 24 00:42:33 2000 GMT
X-MyDeja-Info: XMYDJUIDrobert_dewar
Newsgroups: comp.lang.ada
X-Http-User-Agent: Mozilla/4.61 [en] (OS/2; I)
Date: 2000-04-24T00:00:00+00:00
List-Id: <comp.lang.ada>

In article <vzJM4.1253$t25.356170@news.pacbell.net>,
  tmoran@bix.com wrote:
>      if not OK then
>        Log_And_Raise_Error;
>      end if;
>      return some_value;
>    end some_function;

I find the above code a very poor choice, precisely because,
as Tom notes, it will worry a maintenance programmer as to
what is going on! Far better is

      if not OK then
        Log_And_Raise_Error;
        raise Program_Error;
      end if;

or if you want to take the effort

      if not OK then
        Log_And_Raise_Error;
        raise Impossible_Exception_Cannot_Be_Raised;

Still for those using GNAT, use the opportunity to learn about
pragma No_Return, since it is a very clear way of documenting
the special case of a procedure that never returns.

By the way, I think it is a terrible design choice in Ada 95
that Raise_Exception can return to the caller. We end up special
casing this in GNAT to avoid the warning in this case (raising
Program_Error seems reasonable enough if Raise_Exception returns
and the return path is unblocked.


Sent via Deja.com http://www.deja.com/
Before you buy.