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: 103376,1fbce91fa69716f7
X-Google-Attributes: gid103376,public
From: dennison@telepath.com
Subject: Re: What good are File_Access's?
Date: 1998/07/20
Message-ID: <6p0d97$o7t$1@nnrp1.dejanews.com>#1/1
X-Deja-AN: 373270404
References: <6oo80p$m20$1@nnrp1.dejanews.com> <dewar.900786542@merv>
 <6ovjqp$ki8$1@nnrp1.dejanews.com> <dewar.900954709@merv>
Organization: Deja News - The Leader in Internet Discussion
X-Article-Creation-Date: Mon Jul 20 21:36:39 1998 GMT
Newsgroups: comp.lang.ada
X-Http-User-Agent: Mozilla/4.0 (compatible; MSIE 4.0; Windows NT; Gateway2000)
Date: 1998-07-20T00:00:00+00:00
List-Id: <comp.lang.ada>

In article <dewar.900954709@merv>,
  dewar@merv.cs.nyu.edu (Robert Dewar) wrote:
> <<Ahhhh. That's the answer I was looking for.
> I didn't consider that as a possibility because that method of saving off the
> Current_Output won't work in a multi-tasking environment. You'd need some kind
> of "atomic" save-and-change operation. Since that is %90 of the Ada programs I
> have ever worked on, that doesn't make it too useful.
> >>
>
> Well it simply needs protecting in a multi-tasking environment. You generalloy
> need to have some control over Text_IO anyway (for example, you certainly
> cannot do Put_Line operations on standard output at the same time from
> two separate tasks without proper synchronization.

True. But having to manage task access to the same *file* is a little
different than having to manage task access to the global default for all of
Text_IO. The former can be accomplished by the simple rule "only task X gets
to access file Y" (or by more complicated means). The latter ... hmmm ... it
would be grisly.

You'd really need a default for each task. I guess you could reimplement all
of Text_IO as a task, using Caller ID's to index into an array of defaults.
Yuk.

Yeah, its basicly useless.

T.E.D.

-----== Posted via Deja News, The Leader in Internet Discussion ==-----
http://www.dejanews.com/rg_mkgrp.xp   Create Your Own Free Member Forum