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| From | Kaz Kylheku <kaz@kylheku.com> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: Meta-C question about header order |
| Date | 2014-04-13 05:02 +0000 |
| Organization | Aioe.org NNTP Server |
| Message-ID | <20140412214930.120@kylheku.com> (permalink) |
| References | <bqtj0hF60hpU1@mid.individual.net> <CNh2v.39400$Wy2.31318@en-nntp-16.dc1.easynews.com> <20140412201155.452@kylheku.com> <bquhvdFb55dU5@mid.individual.net> |
On 2014-04-13, Ian Collins <ian-news@hotmail.com> wrote: > Kaz Kylheku wrote: >> On 2014-04-12, Richard Damon <Richard@Damon-Family.org> wrote: >>> On 4/12/14, 3:37 PM, Jens Schweikhardt wrote: >>>> hello, world\n >>>> >>>> consider a small project of 100 C source and 100 header files. >>>> The coding rules require that only C files include headers, >>>> headers are not allowed to include other headers (not sure if >>>> this is 100% the "IWYU - Include What You Use" paradigma). >>>> >>> >>> A rule that says that a header can NOT include other headers, even if it >>> depends on the contents of that header is, in my mind, totally broken. >> >> I used to think so fresh out of school. >> >> But actually, this style is superior because leads to much cleaner code >> organization and faster compilation. It keeps everything "tight". > > The faster compilation argument is a non-starter these days. Personal preference. Even if the recompile is fast thanks to the hardware, I would still rather wait 5 seconds for a recompile than 8 seconds. The faster the machines get, the less I tolerate response and turnaround time. >> I chose this approach in the TXR project, and am very pleased with it. >> I understand now why some people recommend it. >> >> The compiler diagnostics are simpler. None of this: >> >> "Syntax error in line 32 of X >> included from line 42 of Y, >> included from line 15 of Z ..." >> >> Also, the dependencies are easy to understand. If you look at the >> list of #include directives at the top of a .c file, those are >> the files which, if they are touched, will trigger a re-compile >> of this file. And no others! > > And? And, I like it; I think it is beautiful to have an explicit view of the dependencies laid out in the code. Another benefit: no ugly #ifndef SYMBOL / #define SYMBOL ... #endif crap in all the header files! Just a comment block and the definitions! >> It's easy to generate a dependency makefile. If we have a foo.c >> with these contents: >> >> #include <stdio.h> >> #include "a.h" >> #include "b.h" >> #include "foo.h" >> >> then the dependency rule is precisely this: >> >> foo.o: foo.c a.h b.h foo.h > > A decent make will do this for you. I don't know of any make that generates dependencies. Compilers do (e.g gcc -MM). This is nicer. > So would you rather include and maintain all of the headers (and > accompanying platform specific conditional include spaghetti) a > particular library uses in every source file, or just include the > library's public header? All of that crud is the encapsulation referred > to here. When we divide the program into libraries, we are adding a level to the organizational hirarchy. So it would be too pigheaded not to allow the permitted #include level to also increase by one level. The library does encapsulate; as a user of the library, I don't care about how it is divided into modules. Of course a library is a unit, and it should ideally provide one simple header (or one for each major feature area). If a library has some base definitions that are used by several features, then I'd probably want to have a header for those base definitions which must be included before the main features. But all these headers can, internally, include the detailed internal headers: all of the needed ones, in the correct order (which do not include other headers). >> The fact that you have a Makefile (or whatever) which has to list object files >> breaks "encapsulation". > > Not when bringing in a library. Actually yes. If library X also needs library Y, which also needs library Z, you will have to break encapsulation and link in all of these, even though you only have #include "X.h". The documentation for X might say that you need to initialize Y first, etc. The simplicity of #include "X.h" only goes so far.
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Meta-C question about header order Jens Schweikhardt <usenet@schweikhardt.net> - 2014-04-12 19:37 +0000
Re: Meta-C question about header order Keith Thompson <kst-u@mib.org> - 2014-04-12 13:51 -0700
Re: Meta-C question about header order glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-04-13 00:11 +0000
Re: Meta-C question about header order Jens Schweikhardt <usenet@schweikhardt.net> - 2014-04-13 11:40 +0000
Re: Meta-C question about header order "BartC" <bc@freeuk.com> - 2014-04-13 13:10 +0100
Re: Meta-C question about header order Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-04-13 06:29 -0700
Re: Meta-C question about header order Kaz Kylheku <kaz@kylheku.com> - 2014-04-13 14:41 +0000
Re: Meta-C question about header order Ken Brody <kenbrody@spamcop.net> - 2014-04-15 10:36 -0400
Re: Meta-C question about header order Richard Damon <Richard@Damon-Family.org> - 2014-04-12 16:58 -0400
Re: Meta-C question about header order Kaz Kylheku <kaz@kylheku.com> - 2014-04-13 03:40 +0000
Re: Meta-C question about header order Ian Collins <ian-news@hotmail.com> - 2014-04-13 16:26 +1200
Re: Meta-C question about header order Kaz Kylheku <kaz@kylheku.com> - 2014-04-13 05:02 +0000
Re: Meta-C question about header order Ian Collins <ian-news@hotmail.com> - 2014-04-13 17:21 +1200
Re: Meta-C question about header order Ken Brody <kenbrody@spamcop.net> - 2014-04-15 10:59 -0400
Re: Meta-C question about header order Ken Brody <kenbrody@spamcop.net> - 2014-04-15 11:02 -0400
Re: Meta-C question about header order Ken Brody <kenbrody@spamcop.net> - 2014-04-15 10:59 -0400
Re: Meta-C question about header order Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-04-15 08:26 -0700
Re: Meta-C question about header order Kaz Kylheku <kaz@kylheku.com> - 2014-04-15 15:56 +0000
Re: Meta-C question about header order Jens Schweikhardt <usenet@schweikhardt.net> - 2014-04-13 11:34 +0000
Re: Meta-C question about header order Richard Damon <Richard@Damon-Family.org> - 2014-04-13 15:04 -0400
Re: Meta-C question about header order Ken Brody <kenbrody@spamcop.net> - 2014-04-15 10:52 -0400
Re: Meta-C question about header order Ian Collins <ian-news@hotmail.com> - 2014-04-13 11:09 +1200
Re: Meta-C question about header order Jens Schweikhardt <usenet@schweikhardt.net> - 2014-04-13 11:47 +0000
Re: Meta-C question about header order Ian Collins <ian-news@hotmail.com> - 2014-04-14 08:54 +1200
Re: Meta-C question about header order Kaz Kylheku <kaz@kylheku.com> - 2014-04-13 21:37 +0000
Re: Meta-C question about header order Ian Collins <ian-news@hotmail.com> - 2014-04-14 09:49 +1200
Re: Meta-C question about header order Jens Schweikhardt <usenet@schweikhardt.net> - 2014-04-14 19:17 +0000
Re: Meta-C question about header order Ian Collins <ian-news@hotmail.com> - 2014-04-15 10:24 +1200
Re: Meta-C question about header order Jens Schweikhardt <usenet@schweikhardt.net> - 2014-04-16 19:58 +0000
Re: Meta-C question about header order Richard Damon <Richard@Damon-Family.org> - 2014-04-14 21:45 -0400
Re: Meta-C question about header order luser- -droog <luser.droog@gmail.com> - 2014-04-12 16:48 -0700
Re: Meta-C question about header order Jens Schweikhardt <usenet@schweikhardt.net> - 2014-04-13 11:52 +0000
Re: Meta-C question about header order Kaz Kylheku <kaz@kylheku.com> - 2014-04-13 01:04 +0000
Re: Meta-C question about header order "BartC" <bc@freeuk.com> - 2014-04-13 10:15 +0100
Re: Meta-C question about header order Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-04-13 04:06 -0700
Re: Meta-C question about header order Jens Schweikhardt <usenet@schweikhardt.net> - 2014-04-13 12:01 +0000
Re: Meta-C question about header order "BartC" <bc@freeuk.com> - 2014-04-13 13:46 +0100
Re: Meta-C question about header order Jens Schweikhardt <usenet@schweikhardt.net> - 2014-04-13 13:58 +0000
Re: Meta-C question about header order Jens Schweikhardt <usenet@schweikhardt.net> - 2014-04-13 11:29 +0000
Re: Meta-C question about header order Martin Shobe <martin.shobe@yahoo.com> - 2014-04-13 08:48 -0500
Re: Meta-C question about header order Jens Schweikhardt <usenet@schweikhardt.net> - 2014-04-13 14:25 +0000
Re: Meta-C question about header order Kaz Kylheku <kaz@kylheku.com> - 2014-04-13 15:02 +0000
Re: Meta-C question about header order Martin Shobe <martin.shobe@yahoo.com> - 2014-04-13 21:45 -0500
Re: Meta-C question about header order Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-04-14 01:16 -0700
Re: Meta-C question about header order "BartC" <bc@freeuk.com> - 2014-04-14 10:16 +0100
Re: Meta-C question about header order Richard Damon <Richard@Damon-Family.org> - 2014-04-14 21:33 -0400
Re: Meta-C question about header order Kaz Kylheku <kaz@kylheku.com> - 2014-04-14 16:25 +0000
Re: Meta-C question about header order Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-04-14 09:47 -0700
Re: Meta-C question about header order Martin Shobe <martin.shobe@yahoo.com> - 2014-04-14 13:29 -0500
Re: Meta-C question about header order Kaz Kylheku <kaz@kylheku.com> - 2014-04-14 19:31 +0000
Re: Meta-C question about header order Les Cargill <lcargill99@comcast.com> - 2014-04-14 20:03 -0500
Re: Meta-C question about header order Kaz Kylheku <kaz@kylheku.com> - 2014-04-15 01:04 +0000
Re: Meta-C question about header order Keith Thompson <kst-u@mib.org> - 2014-04-14 15:15 -0700
Re: Meta-C question about header order Richard Damon <Richard@Damon-Family.org> - 2014-04-14 22:01 -0400
Re: Meta-C question about header order "BartC" <bc@freeuk.com> - 2014-04-15 09:51 +0100
Re: Meta-C question about header order Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-04-15 06:01 -0700
Re: Meta-C question about header order "BartC" <bc@freeuk.com> - 2014-04-15 14:29 +0100
Re: Meta-C question about header order Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-04-15 10:38 -0700
Re: Meta-C question about header order Kaz Kylheku <kaz@kylheku.com> - 2014-04-15 18:27 +0000
Re: Meta-C question about header order Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-04-15 12:45 -0700
Re: Meta-C question about header order ralph <nt_consulting@yahoo.com> - 2014-04-15 22:02 -0500
Re: Meta-C question about header order Jens Schweikhardt <usenet@schweikhardt.net> - 2014-04-14 17:44 +0000
Re: Meta-C question about header order Tim Rentsch <txr@alumni.caltech.edu> - 2014-04-19 01:25 -0700
Re: Meta-C question about header order Richard Damon <Richard@Damon-Family.org> - 2014-04-19 10:30 -0400
Re: Meta-C question about header order Jens Schweikhardt <usenet@schweikhardt.net> - 2014-04-23 19:47 +0000
Re: Meta-C question about header order James Kuyper <jameskuyper@verizon.net> - 2014-04-23 15:53 -0400
Re: Meta-C question about header order Tim Rentsch <txr@alumni.caltech.edu> - 2014-06-10 09:25 -0700
Re: Meta-C question about header order Jens Schweikhardt <usenet@schweikhardt.net> - 2014-04-23 19:27 +0000
Re: Meta-C question about header order Tim Rentsch <txr@alumni.caltech.edu> - 2014-06-10 09:40 -0700
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