Re: Is there any place to talk about language features?

From	BartC <bc@freeuk.com>
Newsgroups	comp.lang.c
Subject	Re: Is there any place to talk about language features?
Date	2016-09-30 22:30 +0100
Organization	A noiseless patient Spider
Message-ID	<nsmlhh$2sk$1@dont-email.me> (permalink)
References	(11 earlier) <3e7e20c2-c69d-4777-a98a-b7d212f546c9@googlegroups.com> <e57rk4Fa94uU1@mid.individual.net> <21af8abe-28fe-4447-b8a9-db1defa5a848@googlegroups.com> <e57uvtFa94uU2@mid.individual.net> <e00dcebb-a6ef-48f7-97a1-20e43ff288bf@googlegroups.com>

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On 30/09/2016 21:53, Thiago Adams wrote:
> On Friday, September 30, 2016 at 5:07:33 PM UTC-3, Ian Collins wrote:
>> On 10/ 1/16 08:14 AM, Thiago Adams wrote:
>>> On Friday, September 30, 2016 at 4:10:05 PM UTC-3, Ian Collins wrote:
>>> ....
>>>> Which, given a problem such as "Resource X must be freed once all uses
>>>> of it end".  Such a problem is trivial to manage in C++ and far from
>>>> trivial in C.
>>>
>>> Do you mean a shared resource? (shared_ptr?)
>>
>> That's one example, yes.  It is usual practice in C++ to use objects to
>> manage resources.
>
> I find easy to create shared objects in C.
>
> Object * p1 = Create(); //ref counted 1
> Object * p2 = NULL;
>
> p2 = Share(p1);//ref counted 2
>
> Release(p1); //ref counted 1
> Release(p2); //destroyed
>
> share_ptr in C++ is uses atomic counter.
> this is one place where C _Atomic would be useful.
>

I started playing around with reference counting earlier this year (for 
some language project). It sounded easy to start with. It ended up being 
a nightmare.

For a start, suppose Object is a structure that can contain other Object 
references (for tree and list building).

So Release() now has to do a list or tree traversal to free everything 
properly. And you need dedicated Create and Release routines for each 
kind of object.

Or, if you have an array of Objects, now you need to scan each array 
element and call Release on each (and the same for any miscellaneous 
instances of Object in any other data). If a regular struct contains any 
Object references, you can't just copy that struct to another.

Then you have circular references, which either mean things cannot be 
freed, or, if you want to duplicate a structure, you end up in endless 
loops.

It gets better. Suppose you want a pointer to a part of an Object (to 
pass to a function or to do the usual stuff with). Now you can't just 
create a pointer because you have to step the reference count. You can't 
use Share() because that's for a whole object. It starts to get very messy.

-- 
Bart

Thread

Is there any place to talk about language features? Thiago Adams <thiago.adams@gmail.com> - 2016-09-28 09:35 -0700
  Re: Is there any place to talk about language features? Keith Thompson <kst-u@mib.org> - 2016-09-28 09:39 -0700
    Re: Is there any place to talk about language features? Thiago Adams <thiago.adams@gmail.com> - 2016-09-28 09:46 -0700
      Re: Is there any place to talk about language features? Richard Heathfield <rjh@cpax.org.uk> - 2016-09-28 17:53 +0100
      Re: Is there any place to talk about language features? David Brown <david.brown@hesbynett.no> - 2016-09-28 21:21 +0200
      Re: Is there any place to talk about language features? BartC <bc@freeuk.com> - 2016-09-28 20:36 +0100
        Re: Is there any place to talk about language features? Thiago Adams <thiago.adams@gmail.com> - 2016-09-28 13:55 -0700
          Re: Is there any place to talk about language features? Thiago Adams <thiago.adams@gmail.com> - 2016-09-28 14:02 -0700
          Re: Is there any place to talk about language features? Ian Collins <ian-news@hotmail.com> - 2016-09-29 10:03 +1300
            Re: Is there any place to talk about language features? Thiago Adams <thiago.adams@gmail.com> - 2016-09-28 14:13 -0700
              Re: Is there any place to talk about language features? Ian Collins <ian-news@hotmail.com> - 2016-09-29 10:22 +1300
                Re: Is there any place to talk about language features? Robert Latest <boblatest@yahoo.com> - 2016-10-03 08:47 +0000
                Re: Is there any place to talk about language features? James Kuyper <jameskuyper@verizon.net> - 2016-10-03 07:44 -0400
                Re: Is there any place to talk about language features? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-10-03 04:56 -0700
                Re: Is there any place to talk about language features? BartC <bc@freeuk.com> - 2016-10-03 13:18 +0100
                Re: Is there any place to talk about language features? BGB <cr88192@hotmail.com> - 2016-10-03 12:43 -0500
                Re: Is there any place to talk about language features? Ike Naar <ike@iceland.freeshell.org> - 2016-10-03 21:43 +0000
                Re: Is there any place to talk about language features? John Gordon <gordon@panix.com> - 2016-10-03 22:28 +0000
                Re: Is there any place to talk about language features? Thiago Adams <thiago.adams@gmail.com> - 2016-10-03 04:51 -0700
                Re: Is there any place to talk about language features? BartC <bc@freeuk.com> - 2016-10-03 13:10 +0100
                Re: Is there any place to talk about language features? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-10-03 05:48 -0700
                Re: Is there any place to talk about language features? BartC <bc@freeuk.com> - 2016-10-03 14:03 +0100
                Re: Is there any place to talk about language features? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-10-03 14:24 +0100
                Re: Is there any place to talk about language features? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-10-03 07:07 -0700
                Re: Is there any place to talk about language features? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-10-03 19:16 +0100
                Re: Is there any place to talk about language features? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-10-03 07:16 -0700
                Re: Is there any place to talk about language features? supercat@casperkitty.com - 2016-10-03 07:45 -0700
                Re: Is there any place to talk about language features? supercat@casperkitty.com - 2016-10-03 07:57 -0700
                Re: Is there any place to talk about language features? James Kuyper <jameskuyper@verizon.net> - 2016-10-03 08:21 -0400
                Re: Is there any place to talk about language features? Thiago Adams <thiago.adams@gmail.com> - 2016-10-03 05:31 -0700
                Re: Is there any place to talk about language features? supercat@casperkitty.com - 2016-10-03 06:43 -0700
                Re: Is there any place to talk about language features? David Brown <david.brown@hesbynett.no> - 2016-10-03 15:08 +0200
              Re: Is there any place to talk about language features? Thiago Adams <thiago.adams@gmail.com> - 2016-09-28 14:22 -0700
                Re: Is there any place to talk about language features? Keith Thompson <kst-u@mib.org> - 2016-09-28 15:16 -0700
                Re: Is there any place to talk about language features? Thiago Adams <thiago.adams@gmail.com> - 2016-09-28 16:08 -0700
                Re: Is there any place to talk about language features? Keith Thompson <kst-u@mib.org> - 2016-09-28 16:57 -0700
          Re: Is there any place to talk about language features? Keith Thompson <kst-u@mib.org> - 2016-09-28 14:19 -0700
            Re: Is there any place to talk about language features? Thiago Adams <thiago.adams@gmail.com> - 2016-09-28 14:50 -0700
              Re: Is there any place to talk about language features? Thiago Adams <thiago.adams@gmail.com> - 2016-09-28 17:03 -0700
              Re: Is there any place to talk about language features? BartC <bc@freeuk.com> - 2016-09-29 01:08 +0100
                Re: Is there any place to talk about language features? Thiago Adams <thiago.adams@gmail.com> - 2016-09-28 17:33 -0700
                Re: Is there any place to talk about language features? Melzzzzz <Melzzzzz@zzzzz.com> - 2016-09-29 01:02 +0000
                Re: Is there any place to talk about language features? BGB <cr88192@hotmail.com> - 2016-09-29 01:39 -0500
                Re: Is there any place to talk about language features? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-09-29 00:48 -0700
                Re: Is there any place to talk about language features? BGB <cr88192@hotmail.com> - 2016-09-29 11:59 -0500
                Re: Is there any place to talk about language features? Ian Collins <ian-news@hotmail.com> - 2016-10-01 08:09 +1300
                Re: Is there any place to talk about language features? Thiago Adams <thiago.adams@gmail.com> - 2016-09-30 12:14 -0700
                Re: Is there any place to talk about language features? Ian Collins <ian-news@hotmail.com> - 2016-10-01 09:07 +1300
                Re: Is there any place to talk about language features? Thiago Adams <thiago.adams@gmail.com> - 2016-09-30 13:53 -0700
                Re: Is there any place to talk about language features? Gareth Owen <gwowen@gmail.com> - 2016-09-30 22:13 +0100
                Re: Is there any place to talk about language features? raltbos@xs4all.nl (Richard Bos) - 2016-10-01 09:36 +0000
                Re: Is there any place to talk about language features? Jerry Stuckle <jstucklex@attglobal.net> - 2016-10-01 13:04 -0400
                Re: Is there any place to talk about language features? "Chris M. Thomasson" <invalid@invalid.invalid> - 2016-09-30 14:20 -0700
                Re: Is there any place to talk about language features? BartC <bc@freeuk.com> - 2016-09-30 22:30 +0100
                Re: Is there any place to talk about language features? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2016-10-02 07:30 +0000
                Re: Is there any place to talk about language features? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-10-01 01:51 -0700
                Re: Is there any place to talk about language features? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-10-01 10:31 +0100
                Re: Is there any place to talk about language features? Ian Collins <ian-news@hotmail.com> - 2016-10-01 23:22 +1300
                Re: Is there any place to talk about language features? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-10-01 06:15 -0700
                Re: Is there any place to talk about language features? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-10-01 15:28 +0100
                Re: Is there any place to talk about language features? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-10-01 10:07 -0700
                Re: Is there any place to talk about language features? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-10-01 19:52 +0100
                Re: Is there any place to talk about language features? Ian Collins <ian-news@hotmail.com> - 2016-10-02 20:38 +1300
                Re: Is there any place to talk about language features? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-10-02 03:37 -0700
                Re: Is there any place to talk about language features? Ian Collins <ian-news@hotmail.com> - 2016-10-03 08:35 +1300
                Re: Is there any place to talk about language features? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-10-02 15:17 -0700
                Re: Is there any place to talk about language features? Ian Collins <ian-news@hotmail.com> - 2016-10-03 18:29 +1300
                Re: Is there any place to talk about language features? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-10-03 01:09 -0700
                Re: Is there any place to talk about language features? Ian Collins <ian-news@hotmail.com> - 2016-10-04 08:21 +1300
                Re: Is there any place to talk about language features? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-10-03 13:12 -0700
                Re: Is there any place to talk about language features? supercat@casperkitty.com - 2016-10-03 14:34 -0700
                Re: Is there any place to talk about language features? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-10-04 00:47 -0700
                Re: Is there any place to talk about language features? Ike Naar <ike@iceland.freeshell.org> - 2016-10-04 07:49 +0000
                Re: Is there any place to talk about language features? supercat@casperkitty.com - 2016-10-04 07:50 -0700
                Re: Is there any place to talk about language features? Keith Thompson <kst-u@mib.org> - 2016-10-04 08:57 -0700
                Re: Is there any place to talk about language features? supercat@casperkitty.com - 2016-10-04 10:42 -0700
                Re: Is there any place to talk about language features? Ian Collins <ian-news@hotmail.com> - 2016-10-05 15:47 +1300
                Re: Is there any place to talk about language features? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-10-04 20:58 -0700
                Re: Is there any place to talk about language features? Ian Collins <ian-news@hotmail.com> - 2016-10-05 18:14 +1300
                Re: Is there any place to talk about language features? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-10-05 02:15 -0700
                Re: Is there any place to talk about language features? Ian Collins <ian-news@hotmail.com> - 2016-10-05 22:44 +1300
                Re: Is there any place to talk about language features? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-10-05 03:12 -0700
                Re: Is there any place to talk about language features? Ian Collins <ian-news@hotmail.com> - 2016-10-06 15:38 +1300
                Re: Is there any place to talk about language features? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-10-05 19:50 -0700
                Re: Is there any place to talk about language features? Ian Collins <ian-news@hotmail.com> - 2016-10-06 16:25 +1300
                Re: Is there any place to talk about language features? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-10-05 21:19 -0700
                Re: Is there any place to talk about language features? Ian Collins <ian-news@hotmail.com> - 2016-10-06 18:11 +1300
                Re: Is there any place to talk about language features? Gareth Owen <gwowen@gmail.com> - 2016-10-06 06:38 +0100
                Re: Is there any place to talk about language features? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-10-06 00:36 -0700
                Re: Is there any place to talk about language features? gwowen <gwowen@gmail.com> - 2016-10-06 07:33 -0700
                Re: Is there any place to talk about language features? supercat@casperkitty.com - 2016-10-06 09:00 -0700
                Re: Is there any place to talk about language features? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-10-07 00:32 -0700
                Re: Is there any place to talk about language features? Thiago Adams <thiago.adams@gmail.com> - 2016-10-07 05:05 -0700
                Re: Is there any place to talk about language features? supercat@casperkitty.com - 2016-10-07 08:13 -0700
                Re: Is there any place to talk about language features? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-10-07 00:20 -0700
                Re: Is there any place to talk about language features? Gareth Owen <gwowen@gmail.com> - 2016-10-07 17:01 +0100
                Re: Is there any place to talk about language features? Les Cargill <lcargill99@comcast.com> - 2016-10-05 12:45 -0500
                Re: Is there any place to talk about language features? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-10-05 11:12 +0100
                Re: Is there any place to talk about language features? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-10-05 03:15 -0700
                Re: Is there any place to talk about language features? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-10-05 14:41 +0100
                Re: Is there any place to talk about language features? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-10-05 08:01 -0700
                Re: Is there any place to talk about language features? supercat@casperkitty.com - 2016-10-05 08:41 -0700
                Re: Is there any place to talk about language features? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-10-05 10:29 -0700
                Re: Is there any place to talk about language features? Thiago Adams <thiago.adams@gmail.com> - 2016-10-05 12:29 -0700
                Re: Is there any place to talk about language features? BartC <bc@freeuk.com> - 2016-10-05 11:08 +0100
                Re: Is there any place to talk about language features? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-10-05 14:35 +0100
                Re: Is there any place to talk about language features? BartC <bc@freeuk.com> - 2016-10-05 18:15 +0100
                Re: Is there any place to talk about language features? supercat@casperkitty.com - 2016-10-05 10:38 -0700
                Re: Is there any place to talk about language features? BartC <bc@freeuk.com> - 2016-10-05 19:14 +0100
                Re: Is there any place to talk about language features? supercat@casperkitty.com - 2016-10-05 11:56 -0700
                Re: Is there any place to talk about language features? Thiago Adams <thiago.adams@gmail.com> - 2016-10-05 11:57 -0700
                Re: Is there any place to talk about language features? Keith Thompson <kst-u@mib.org> - 2016-10-05 12:18 -0700
                Re: Is there any place to talk about language features? David Brown <david.brown@hesbynett.no> - 2016-10-05 21:49 +0200
                Re: Is there any place to talk about language features? Thiago Adams <thiago.adams@gmail.com> - 2016-10-05 13:07 -0700
                Re: Is there any place to talk about language features? "James R. Kuyper" <jameskuyper@verizon.net> - 2016-10-05 16:23 -0400
                Re: Is there any place to talk about language features? David Brown <david.brown@hesbynett.no> - 2016-10-06 14:26 +0200
                Re: Is there any place to talk about language features? supercat@casperkitty.com - 2016-10-05 13:56 -0700
                Re: Is there any place to talk about language features? BartC <bc@freeuk.com> - 2016-10-06 14:17 +0100
                Re: Is there any place to talk about language features? David Brown <david.brown@hesbynett.no> - 2016-10-06 15:53 +0200
                Re: Is there any place to talk about language features? Keith Thompson <kst-u@mib.org> - 2016-10-06 09:12 -0700
                Re: Is there any place to talk about language features? supercat@casperkitty.com - 2016-10-06 11:28 -0700
                Re: Is there any place to talk about language features? Ian Collins <ian-news@hotmail.com> - 2016-10-06 15:31 +1300
                Re: Is there any place to talk about language features? Ian Collins <ian-news@hotmail.com> - 2016-10-06 15:32 +1300
                Re: Is there any place to talk about language features? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-10-05 19:43 -0700
                Re: Is there any place to talk about language features? Ian Collins <ian-news@hotmail.com> - 2016-10-06 16:05 +1300
                Re: Is there any place to talk about language features? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2016-10-02 07:24 +0000
                Re: Is there any place to talk about language features? supercat@casperkitty.com - 2016-09-30 16:17 -0700
                Re: Is there any place to talk about language features? raltbos@xs4all.nl (Richard Bos) - 2016-10-01 09:39 +0000
                Re: Is there any place to talk about language features? supercat@casperkitty.com - 2016-10-01 14:11 -0700
            Re: Is there any place to talk about language features? Thiago Adams <thiago.adams@gmail.com> - 2016-09-29 07:47 -0700
            Re: Is there any place to talk about language features? Thiago Adams <thiago.adams@gmail.com> - 2016-09-29 10:25 -0700
  Re: Is there any place to talk about language features? "James R. Kuyper" <jameskuyper@verizon.net> - 2016-09-28 12:59 -0400
    Re: Is there any place to talk about language features? Richard Heathfield <rjh@cpax.org.uk> - 2016-09-28 18:30 +0100
      Re: Is there any place to talk about language features? Keith Thompson <kst-u@mib.org> - 2016-09-28 12:10 -0700
    Re: Is there any place to talk about language features? James Harris <james.harris.1@gmail.com> - 2016-09-28 20:20 +0100

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