Re: Forward declarations ... the straw that broke the camel's back

From	BartC <bc@freeuk.com>
Newsgroups	comp.lang.c
Subject	Re: Forward declarations ... the straw that broke the camel's back
Date	2016-06-30 22:22 +0100
Organization	A noiseless patient Spider
Message-ID	<nl42ja$k8a$1@dont-email.me> (permalink)
References	(3 earlier) <dtjk6hFrf0bU1@mid.individual.net> <nl2sgm$7ia$1@dont-email.me> <dtkdq8Fdt6U1@mid.individual.net> <nl36pt$cmm$1@dont-email.me> <nl3uop$6nb$1@dont-email.me>

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On 30/06/2016 21:17, jacobnavia wrote:
> Le 30/06/2016 à 15:28, BartC a écrit :
>> If there is a global function F used by all 50 modules M1 to M50, you
>> either declare F in a single header H included in all M modules, or you
>> have to duplicate the declaration for F in M1 to M50, possibly by
>> creating headers H1 to H50.
>
> Wait, we are speaking about structured programming isn't it?
>
> You make modules, for instance in the lcc-win system I have some headers
> like:
>
> "debugger.h"
> "editor.h"
> "make.h"
>

Yes, and if you have 50 of those, then each module will need to include 
up to 0 to 50 headers (between 0 and 2500 includes in all). If 17 
modules include "editor.h", then those 17 will need recompiling when 
editor.c changes.

So you still have the problem of dependencies requiring multiple 
recompiles; it doesn't solve it as Ian Collins was suggesting.

> What are we speaking about?
> The compilation of a 5 000 line source file including some headers, etc
> takes 0.78 seconds using lcc-win. In a 50 000 line project a full
> recompilation would take you the staggering time of around 7.8 seconds,
> an eternity.

7.8 seconds is long enough that I would actually find something else to 
do while waiting. (Check an on-line forum, etc.)

6K lines per second sounds remarkably low for a C compiler written in C 
(presumably).

I'm working on compiler projects now that I estimate could achieve 
500Klps for compiling source code to in-memory native code (I've managed 
0.8 to 1.0Mlps for compiling byte-code).

That 50,000-line project would be compiled entirely in 0.1 seconds. 
(Although, if it's C source code, that can introduce extra challenges; 
see below.)

>
> And even in the case of recompiling a 500 000 line project it would be
> just over a minute...

And 1 second for this one! (Figures include reading source code into 
memory, but assume file-caching by the OS has taken place. They exclude 
writing out code to an executable file. However code could also be 
fixed-up to run directly in memory.)

There is a C compiler called Tiny C which also has compile times into 
six figures per second. But as I suggested above, having to keep 
recompiling the header files can use up much of that throughput.

That's why it's good to discuss possible alternatives to C's header system.

-- 
Bartc

Thread

Forward declarations ... the straw that broke the camel's back "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-06-29 10:36 -0700
  Re: Forward declarations ... the straw that broke the camel's back supercat@casperkitty.com - 2016-06-29 16:04 -0700
    Re: Forward declarations ... the straw that broke the camel's back "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-06-29 16:30 -0700
      Re: Forward declarations ... the straw that broke the camel's back Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-06-29 19:52 -0700
        Re: Forward declarations ... the straw that broke the camel's back Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-06-30 13:00 +0100
          Re: Forward declarations ... the straw that broke the camel's back "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-06-30 05:42 -0700
            Re: Forward declarations ... the straw that broke the camel's back BartC <bc@freeuk.com> - 2016-06-30 18:11 +0100
              Re: Forward declarations ... the straw that broke the camel's back "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-06-30 10:30 -0700
                Re: Forward declarations ... the straw that broke the camel's back BartC <bc@freeuk.com> - 2016-06-30 19:54 +0100
                Re: Forward declarations ... the straw that broke the camel's back "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-06-30 12:31 -0700
                Re: Forward declarations ... the straw that broke the camel's back Ian Collins <ian-news@hotmail.com> - 2016-07-01 07:59 +1200
                Re: Forward declarations ... the straw that broke the camel's back Gareth Owen <gwowen@gmail.com> - 2016-06-30 21:31 +0100
                Re: Forward declarations ... the straw that broke the camel's back "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-06-30 14:19 -0700
                Re: Forward declarations ... the straw that broke the camel's back "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-06-30 14:31 -0700
                Re: Forward declarations ... the straw that broke the camel's back BartC <bc@freeuk.com> - 2016-06-30 21:18 +0100
                Re: Forward declarations ... the straw that broke the camel's back "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-06-30 14:26 -0700
                Re: Forward declarations ... the straw that broke the camel's back BartC <bc@freeuk.com> - 2016-06-30 22:44 +0100
                Re: Forward declarations ... the straw that broke the camel's back "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-06-30 17:23 -0700
                Re: Forward declarations ... the straw that broke the camel's back David Brown <david.brown@hesbynett.no> - 2016-07-05 21:38 +0200
                Re: Forward declarations ... the straw that broke the camel's back Richard Heathfield <rjh@cpax.org.uk> - 2016-07-05 21:05 +0100
                Re: Forward declarations ... the straw that broke the camel's back "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-07-05 13:32 -0700
                Re: Forward declarations ... the straw that broke the camel's back David Brown <david.brown@hesbynett.no> - 2016-07-05 23:20 +0200
                Re: Forward declarations ... the straw that broke the camel's back "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-07-05 14:25 -0700
                Re: Forward declarations ... the straw that broke the camel's back "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-07-05 16:14 -0700
                Re: Forward declarations ... the straw that broke the camel's back David Brown <david.brown@hesbynett.no> - 2016-07-06 11:18 +0200
                Re: Forward declarations ... the straw that broke the camel's back "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-07-06 03:36 -0700
                Re: Forward declarations ... the straw that broke the camel's back "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-07-05 16:23 -0700
                Re: Forward declarations ... the straw that broke the camel's back David Brown <david.brown@hesbynett.no> - 2016-07-06 11:29 +0200
                Re: Forward declarations ... the straw that broke the camel's back Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-07-06 02:49 -0700
                Re: Forward declarations ... the straw that broke the camel's back "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-07-06 05:18 -0700
                Re: Forward declarations ... the straw that broke the camel's back BartC <bc@freeuk.com> - 2016-07-06 13:57 +0100
                Re: Forward declarations ... the straw that broke the camel's back "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-07-06 06:24 -0700
                Re: Forward declarations ... the straw that broke the camel's back David Brown <david.brown@hesbynett.no> - 2016-07-06 15:22 +0200
                Re: Forward declarations ... the straw that broke the camel's back "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-07-06 07:12 -0700
                Re: Forward declarations ... the straw that broke the camel's back Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-07-06 08:08 -0700
                Re: Forward declarations ... the straw that broke the camel's back supercat@casperkitty.com - 2016-07-06 09:00 -0700
                Re: Forward declarations ... the straw that broke the camel's back Ian Collins <ian-news@hotmail.com> - 2016-07-07 08:01 +1200
                Re: Forward declarations ... the straw that broke the camel's back supercat@casperkitty.com - 2016-07-06 13:30 -0700
                Re: Forward declarations ... the straw that broke the camel's back BartC <bc@freeuk.com> - 2016-07-06 17:30 +0100
    Re: Forward declarations ... the straw that broke the camel's back BartC <bc@freeuk.com> - 2016-06-30 00:39 +0100
      Re: Forward declarations ... the straw that broke the camel's back jacobnavia <jacob@jacob.remcomp.fr> - 2016-06-30 22:08 +0200
  Re: Forward declarations ... the straw that broke the camel's back gordonb.h5sc5@burditt.org (Gordon Burditt) - 2016-06-29 20:52 -0500
    Re: Forward declarations ... the straw that broke the camel's back "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-06-29 19:00 -0700
      Re: Forward declarations ... the straw that broke the camel's back Ian Collins <ian-news@hotmail.com> - 2016-06-30 16:06 +1200
        Re: Forward declarations ... the straw that broke the camel's back Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-06-30 02:48 -0700
          Re: Forward declarations ... the straw that broke the camel's back Ian Collins <ian-news@hotmail.com> - 2016-06-30 23:25 +1200
            Re: Forward declarations ... the straw that broke the camel's back Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-06-30 04:39 -0700
              Re: Forward declarations ... the straw that broke the camel's back jacobnavia <jacob@jacob.remcomp.fr> - 2016-06-30 21:50 +0200
            Re: Forward declarations ... the straw that broke the camel's back "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-06-30 06:49 -0700
              Re: Forward declarations ... the straw that broke the camel's back jacobnavia <jacob@jacob.remcomp.fr> - 2016-06-30 22:23 +0200
                Re: Forward declarations ... the straw that broke the camel's back "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-07-04 10:43 -0700
                Vaporware (Was: Forward declarations ... the straw that broke ...) gazelle@shell.xmission.com (Kenny McCormack) - 2016-07-04 17:59 +0000
                Re: Forward declarations ... the straw that broke the camel's back Randy Howard <rhoward.mx@EverybodyUsesIt.com> - 2016-07-06 12:38 -0500
                Re: Forward declarations ... the straw that broke the camel's back "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2016-07-06 11:38 -0700
          Re: Forward declarations ... the straw that broke the camel's back Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-06-30 19:51 +0100
            Re: Forward declarations ... the straw that broke the camel's back jacobnavia <jacob@jacob.remcomp.fr> - 2016-06-30 21:59 +0200
              Re: Forward declarations ... the straw that broke the camel's back Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-07-01 01:05 -0700
        Re: Forward declarations ... the straw that broke the camel's back BartC <bc@freeuk.com> - 2016-06-30 11:32 +0100
          Re: Forward declarations ... the straw that broke the camel's back Ian Collins <ian-news@hotmail.com> - 2016-06-30 23:23 +1200
            Re: Forward declarations ... the straw that broke the camel's back BartC <bc@freeuk.com> - 2016-06-30 14:28 +0100
              Re: Forward declarations ... the straw that broke the camel's back supercat@casperkitty.com - 2016-06-30 08:24 -0700
                Re: Forward declarations ... the straw that broke the camel's back BartC <bc@freeuk.com> - 2016-06-30 16:56 +0100
              Re: Forward declarations ... the straw that broke the camel's back jacobnavia <jacob@jacob.remcomp.fr> - 2016-06-30 22:17 +0200
                Re: Forward declarations ... the straw that broke the camel's back BartC <bc@freeuk.com> - 2016-06-30 22:22 +0100
                Re: Forward declarations ... the straw that broke the camel's back jacobnavia <jacob@jacob.remcomp.fr> - 2016-07-01 08:25 +0200
                Re: Forward declarations ... the straw that broke the camel's back BartC <bc@freeuk.com> - 2016-07-01 12:09 +0100

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