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,d1df6bc3799debed
X-Google-Attributes: gid103376,public
From: eachus@spectre.mitre.org (Robert I. Eachus)
Subject: Re: Syntax for tagged record types (was Re: Not intended for use in
 medical,)
Date: 1997/05/28
Message-ID: <EACHUS.97May27230116@spectre.mitre.org>#1/1
X-Deja-AN: 244410826
Distribution: world
References: <3.0.32.19970423164855.00746db8@mail.4dcomm.com>
 <dewar.862775250@merv> <5kl9qc$g4d@bcrkh13.bnr.ca>
 <5kmek2$9re@bcrkh13.bnr.ca> <E9rMuy.Hs0@world.std.com> <dewar.863062734@merv>
 <33727FA5.5C7A@sprintmail.com> <dewar.863254456@merv>
 <3374C19F.15FE@sprintmail.com> <dewar.863323812@merv>
 <3376CF85.3E15@sprintmail.com> <EACHUS.97May16200104@spectre.mitre.org>
 <dewar.863877808@merv> <dewar.863880940@merv> <JSA.97May17193543@alexandria>
 <33828299.2A3@world.std.com> <mheaney-ya023680002005972314260001@news.ni.net>
 <JSA.97May21160340@alexandria>
 <mheaney-ya023680002105972302430001@news.ni.net>
 <EACHUS.97May22142002@spectre.mitre.org>
 <mheaney-ya023680002505971159220001@news.ni.net>
Organization: The Mitre Corp., Bedford, MA.
Newsgroups: comp.lang.ada
Date: 1997-05-28T00:00:00+00:00
List-Id: <comp.lang.ada>



   I said:

   >   declare
   >     The_File: New_IO.File_Access := 
   >        New_IO.Open(Name => "my_file.dat", Mode => In_Mode)'Access;
   >   begin
   >
   >   No reason you can't write that package if you want.  I would have
   >the Open return a File_Access value, and would either have garbage
   >collection semantics (via reference counts) for File_Type, or just not
   >make it visible at all.  But those are just details.

In article <mheaney-ya023680002505971159220001@news.ni.net> mheaney@ni.net (Matthew Heaney) writes:

   > Good idea, but I was trying to avoid using heap.

   The thought that avoiding allocators in your code will avoid heap
use when opening a file makes my head swim!  Where does this insanity
end?  Does anyone know of a file system that allows "real" file
objects to be deallocated or trashed by the user by accident?  No?
Okay, where do you think the real file buffers reside?  On the user
stack?  On the system stack?  How about in a system managed heap?

   On Unix, at least on Unix of a few years ago, I could have only
twenty file descriptors open at a time.  So use my suggestion above,
disappear the File_Type from the user's view, and put everything into
an array of twenty objects in the package body.

   What has this accomplished?  Nothing.  Much better would be to have
an array of File_Access values and allocate objects from the heap when
the file is opened, and deallocate them when the file is closed.

--

					Robert I. Eachus

with Standard_Disclaimer;
use  Standard_Disclaimer;
function Message (Text: in Clever_Ideas) return Better_Ideas is...