Re: Is goto Still Considered Harmful?

From	Stephen Sprunk <stephen@sprunk.org>
Newsgroups	comp.lang.c
Subject	Re: Is goto Still Considered Harmful?
Date	2014-04-09 14:30 -0500
Organization	A noiseless patient Spider
Message-ID	<li475d$sij$1@dont-email.me> (permalink)
References	(11 earlier) <20140325084738.938@kylheku.com> <lhce8t$fk6$1@dont-email.me> <5339BFE3.9010703@verizon.net> <lhn2q7$6h6$1@dont-email.me> <533F200A.5070806@verizon.net>

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On 04-Apr-14 16:11, James Kuyper wrote:
> On 04/04/2014 03:56 PM, Stephen Sprunk wrote:
>> On 31-Mar-14 14:20, James Kuyper wrote:
>>> On 03/31/2014 03:05 PM, Stephen Sprunk wrote:
>>>> Unit tests mean _every_ function is called from at least two
>>>> places.
>>> 
>>> That depends upon how you define unit tests. For purposes of
>>> unit testing, I treat functions with internal linkage as part of
>>> the function(s) with external linkage in the same translation
>>> unit that (directly or indirectly) call them. If they have any
>>> feature which cannot be properly tested through calls to those
>>> externally linked functions, then that generally means that the
>>> feature is either unnecessary or at least badly designed.
>> 
>> To me, the purpose of unit testing is to prove the code is correct
>> (as defined by the design docs), and one cannot prove a function is
>> correct until you've proven that all the functions it _calls_ are
>> correct.
> 
> True, but if Y can only be called by X, that doesn't prevent you
> from testing Y; it just means that you have to test Y by calling X.
> I've written more than a few such test drivers. In my experience, if
> there's a good reason for giving Y internal linkage, the fact that
> it's not directly callable by the test driver is seldom a serious
> barrier to testing it.

You can only thoroughly test Y if you can prod X into calling Y with all
possible (or at least interesting) values.  If X is well-written, it may
reject or avoid bug-triggering values before they get passed to Y, so
you don't know Y can actually handle them (i.e. fail) correctly, and you
don't get to test X's handling of Y's failure.

>>> ... Well-designed programs stress your short-term memory capacity
>>> much less than poorly designed programs, because they're easier
>>> to understand.
>> 
>> Fair enough, though I think of "large" in terms of complexity
>> rather than absolute size. ...
> 
> I can agree with that; greater size allows greater complexity, but
> it does not mandate it. However, as I said earlier, most of the 
> uncomplicated large functions I've ever seen were either reading into
> or writing from badly designed data structures.

That's one common case, but not the only one I've encountered.

>> ... A short, complex function can test my mental limits more than a
>> long, simple one; the former is also more likely to contain hidden
>> bugs, and that seems like inherently bad design.
>> 
>> For an example, just look at the IOCCC; most submissions are
>> mercifully short yet more mentally taxing than a typical real-world
>> program that's ten or even a hundred times their size.  And I still
>> don't understand that "RSA in 5 lines" Perl T-shirt, which puts
>> even most IOCCC code to shame.
> 
> Does the expanded version with annotations at the bottom of 
> <http://www.cypherspace.org/rsa/pureperl.html> help? I haven't
> bothered to try to understand it, but it doesn't look that bad
> (unless you don't know perl, of course).

I've seen the annotations and they do help, but it's complex enough that
I can't keep the entire thing in my head at once.  That was necessary to
fit it on a T-shirt (or signature), but in another context it'd be bad
design.

S

-- 
Stephen Sprunk         "God does not play dice."  --Albert Einstein
CCIE #3723         "God is an inveterate gambler, and He throws the
K5SSS        dice at every possible opportunity." --Stephen Hawking

Thread

Is goto Still Considered Harmful? Lynn McGuire <lmc@winsim.com> - 2014-03-12 11:02 -0500
  Re: Is goto Still Considered Harmful? James Kuyper <jameskuyper@verizon.net> - 2014-03-12 12:17 -0400
  Re: Is goto Still Considered Harmful? nospam@see.signature (Richard Maine) - 2014-03-12 09:20 -0700
    Re: Is goto Still Considered Harmful? Lynn McGuire <lmc@winsim.com> - 2014-03-18 16:30 -0500
      Re: Is goto Still Considered Harmful? Geoff <geoff@invalid.invalid> - 2014-03-18 17:36 -0700
        Re: Is goto Still Considered Harmful? James Kuyper <jameskuyper@verizon.net> - 2014-03-19 07:34 -0400
          Re: Is goto Still Considered Harmful? "BartC" <bc@freeuk.com> - 2014-03-19 12:08 +0000
            Re: Is goto Still Considered Harmful? James Kuyper <jameskuyper@verizon.net> - 2014-03-19 10:07 -0400
              Re: Is goto Still Considered Harmful? Richard <rgrdev_@gmail.com> - 2014-03-19 17:05 +0100
            Re: Is goto Still Considered Harmful? Lynn McGuire <lmc@winsim.com> - 2014-03-19 12:27 -0500
      Re: Is goto Still Considered Harmful? "Terence" <tbwright@bigpond.net.au> - 2014-03-19 20:35 +1100
        Re: Is goto Still Considered Harmful? Lynn McGuire <lmc@winsim.com> - 2014-03-19 12:26 -0500
  Re: Is goto Still Considered Harmful? Kaz Kylheku <kaz@kylheku.com> - 2014-03-12 16:47 +0000
    Re: Is goto Still Considered Harmful? Jos Bergervoet <jos.bergervoet@xs4all.nl> - 2014-03-12 19:07 +0100
      Re: Is goto Still Considered Harmful? Andrew Cooper <root@127.0.0.1> - 2014-03-12 23:36 +0000
        Re: Is goto Still Considered Harmful? Kaz Kylheku <kaz@kylheku.com> - 2014-03-13 00:23 +0000
          Re: Is goto Still Considered Harmful? Andrew Cooper <root@127.0.0.1> - 2014-03-13 01:18 +0000
            Re: Is goto Still Considered Harmful? Kaz Kylheku <kaz@kylheku.com> - 2014-03-13 02:08 +0000
              Re: Is goto Still Considered Harmful? Andrew Cooper <root@127.0.0.1> - 2014-03-13 02:21 +0000
              Re: Is goto Still Considered Harmful? David Brown <david.brown@hesbynett.no> - 2014-03-13 11:17 +0100
        Re: Is goto Still Considered Harmful? Melzzzzz <mel@zzzzz.invalid> - 2014-03-13 01:53 +0100
      Re: Is goto Still Considered Harmful? Les Cargill <lcargill99@comcast.com> - 2014-03-13 01:46 -0500
    Re: Is goto Still Considered Harmful? Johannes Bauer <dfnsonfsduifb@gmx.de> - 2014-03-13 10:56 +0100
    Re: Is goto Still Considered Harmful? "Nasser M. Abbasi" <nma@12000.org> - 2014-03-16 08:18 -0500
      Re: Is goto Still Considered Harmful? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-03-16 15:18 +0000
        Re: Is goto Still Considered Harmful? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-03-20 11:36 -0700
  Re: Is goto Still Considered Harmful? "BartC" <bc@freeuk.com> - 2014-03-12 18:50 +0000
    Re: Is goto Still Considered Harmful? <william@wilbur.25thandClement.com> - 2014-03-12 12:49 -0700
    Re: Is goto Still Considered Harmful? "Qolin" <noone@nowhere.com> - 2014-03-12 21:54 +0000
      Re: Is goto Still Considered Harmful? Lynn McGuire <lmc@winsim.com> - 2014-03-12 16:57 -0500
      Re: Is goto Still Considered Harmful? Keith Thompson <kst-u@mib.org> - 2014-03-12 15:36 -0700
        Re: Is goto Still Considered Harmful? James Kuyper <jameskuyper@verizon.net> - 2014-03-12 19:02 -0400
          Re: Is goto Still Considered Harmful? Keith Thompson <kst-u@mib.org> - 2014-03-12 16:58 -0700
            Re: Is goto Still Considered Harmful? James Kuyper <jameskuyper@verizon.net> - 2014-03-12 20:09 -0400
        Re: Is goto Still Considered Harmful? Keith Thompson <kst-u@mib.org> - 2014-03-12 16:44 -0700
      Re: Is goto Still Considered Harmful? Robert Wessel <robertwessel2@yahoo.com> - 2014-03-12 23:40 -0500
        Re: Is goto Still Considered Harmful? David Brown <david.brown@hesbynett.no> - 2014-03-13 11:25 +0100
        Re: Is goto Still Considered Harmful? Thomas Jahns <jahns@idontlikespam.dkrz.de> - 2014-03-14 11:24 +0100
          Re: Is goto Still Considered Harmful? Robert Wessel <robertwessel2@yahoo.com> - 2014-03-14 23:32 -0500
          Re: Is goto Still Considered Harmful? Dr Nick <nospam-4@temporary-address.org.uk> - 2014-03-15 13:43 +0000
            Re: Is goto Still Considered Harmful? David Brown <david.brown@hesbynett.no> - 2014-03-15 16:28 +0100
              Re: Is goto Still Considered Harmful? Dr Nick <nospam-4@temporary-address.org.uk> - 2014-03-15 16:01 +0000
                Re: Is goto Still Considered Harmful? David Brown <david.brown@hesbynett.no> - 2014-03-17 08:51 +0100
    Re: Is goto Still Considered Harmful? David Brown <david.brown@hesbynett.no> - 2014-03-13 11:22 +0100
  Re: Is goto Still Considered Harmful? ralph <nt_consulting@yahoo.com> - 2014-03-12 15:34 -0500
  Re: Is goto Still Considered Harmful? "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2014-03-12 17:48 -0700
  Re: Is goto Still Considered Harmful? jt@toerring.de (Jens Thoms Toerring) - 2014-03-13 01:06 +0000
    Re: Is goto Still Considered Harmful? wilson <winslole@udayton.edu> - 2014-03-13 03:59 -0400
      Re: Is goto Still Considered Harmful? wilson <winslole@udayton.edu> - 2014-03-13 05:02 -0400
        Re: Is goto Still Considered Harmful? Richard Damon <Richard@Damon-Family.org> - 2014-03-13 08:42 -0400
          Re: Is goto Still Considered Harmful? gazelle@shell.xmission.com (Kenny McCormack) - 2014-03-13 14:45 +0000
    Re: Is goto Still Considered Harmful? Louis Krupp <lkrupp@nospam.pssw.com.invalid> - 2014-03-13 07:42 -0600
      Re: Is goto Still Considered Harmful? Richard <rgrdev_@gmail.com> - 2014-03-13 14:56 +0100
  Re: Is goto Still Considered Harmful? Wolfgang Kilian <kilian@invalid.com> - 2014-03-13 09:10 +0100
  Re: Is goto Still Considered Harmful? mark.bluemel@gmail.com - 2014-03-13 08:02 -0700
  Re: Is goto Still Considered Harmful? Thomas Koenig <tkoenig@netcologne.de> - 2014-03-13 21:09 +0000
    Re: Is goto Still Considered Harmful? "Qolin" <noone@nowhere.com> - 2014-03-13 21:24 +0000
      Re: Is goto Still Considered Harmful? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-03-13 22:36 +0000
        Re: Is goto Still Considered Harmful? Robert Wessel <robertwessel2@yahoo.com> - 2014-03-13 23:02 -0500
          Re: Is goto Still Considered Harmful? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-03-14 04:07 +0000
            Re: Is goto Still Considered Harmful? Robert Wessel <robertwessel2@yahoo.com> - 2014-03-13 23:56 -0500
          Re: Is goto Still Considered Harmful? helbig@astro.multiCLOTHESvax.de (Phillip Helbig---undress to reply) - 2014-03-14 09:17 +0000
    Re: Is goto Still Considered Harmful? Kaz Kylheku <kaz@kylheku.com> - 2014-03-13 22:42 +0000
      Re: Is goto Still Considered Harmful? "James Van Buskirk" <not_valid@comcast.net> - 2014-03-13 17:13 -0600
        Re: Is goto Still Considered Harmful? Keith Thompson <kst-u@mib.org> - 2014-03-13 16:46 -0700
          Re: Is goto Still Considered Harmful? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-03-14 01:17 +0000
            Re: Is goto Still Considered Harmful? Robert Wessel <robertwessel2@yahoo.com> - 2014-03-13 23:04 -0500
              Re: Is goto Still Considered Harmful? David Brown <david.brown@hesbynett.no> - 2014-03-14 10:41 +0100
                Re: Is goto Still Considered Harmful? Kaz Kylheku <kaz@kylheku.com> - 2014-03-14 09:55 +0000
                Re: Is goto Still Considered Harmful? David Brown <david.brown@hesbynett.no> - 2014-03-14 13:16 +0100
                Re: Is goto Still Considered Harmful? Seebs <usenet-nospam@seebs.net> - 2014-03-18 21:08 +0000
                Re: Is goto Still Considered Harmful? James Kuyper <jameskuyper@verizon.net> - 2014-03-18 17:41 -0400
        Re: Is goto Still Considered Harmful? Kaz Kylheku <kaz@kylheku.com> - 2014-03-14 00:45 +0000
          Re: Is goto Still Considered Harmful? "James Van Buskirk" <not_valid@comcast.net> - 2014-03-13 21:40 -0600
            Re: Is goto Still Considered Harmful? James Kuyper <jameskuyper@verizon.net> - 2014-03-14 01:02 -0400
              Re: Is goto Still Considered Harmful? "James Van Buskirk" <not_valid@comcast.net> - 2014-03-14 10:36 -0600
                Re: Is goto Still Considered Harmful? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-03-14 17:30 +0000
                Re: Is goto Still Considered Harmful? James Kuyper <jameskuyper@verizon.net> - 2014-03-14 13:51 -0400
                Re: Is goto Still Considered Harmful? Keith Thompson <kst-u@mib.org> - 2014-03-14 13:12 -0700
                Re: Is goto Still Considered Harmful? Tim Rentsch <txr@alumni.caltech.edu> - 2014-03-29 06:46 -0700
            Re: Is goto Still Considered Harmful? Kaz Kylheku <kaz@kylheku.com> - 2014-03-14 05:29 +0000
              Re: Is goto Still Considered Harmful? "James Van Buskirk" <not_valid@comcast.net> - 2014-03-14 10:47 -0600
                Re: Is goto Still Considered Harmful? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-03-14 17:43 +0000
                Re: Is goto Still Considered Harmful? James Kuyper <jameskuyper@verizon.net> - 2014-03-14 13:52 -0400
            Re: Is goto Still Considered Harmful? Stephen Sprunk <stephen@sprunk.org> - 2014-03-16 17:15 -0500
              Re: Is goto Still Considered Harmful? Keith Thompson <kst-u@mib.org> - 2014-03-16 16:04 -0700
    Re: Is goto Still Considered Harmful? Kaz Kylheku <kaz@kylheku.com> - 2014-03-14 05:11 +0000
      Re: Is goto Still Considered Harmful? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-03-14 06:00 +0000
  Re: Is goto Still Considered Harmful? "Terence" <tbwright@bigpond.net.au> - 2014-03-14 08:32 +1100
    Re: Is goto Still Considered Harmful? Richard Damon <Richard@Damon-Family.org> - 2014-03-14 23:10 -0400
  Re: Is goto Still Considered Harmful? Rosario193 <Rosario@invalid.invalid> - 2014-03-14 02:18 +0100
    Re: Is goto Still Considered Harmful? Lynn McGuire <lmc@winsim.com> - 2014-03-18 16:14 -0500
  Re: Is goto Still Considered Harmful? John Bode <jfbode1029@gmail.com> - 2014-03-24 07:52 -0700
    Re: Is goto Still Considered Harmful? Ken Brody <kenbrody@spamcop.net> - 2014-03-24 11:20 -0400
      Re: Is goto Still Considered Harmful? "BartC" <bc@freeuk.com> - 2014-03-24 17:08 +0000
      Re: Is goto Still Considered Harmful? Ken Brody <kenbrody@spamcop.net> - 2014-03-25 14:06 -0400
        Re: Is goto Still Considered Harmful? Lowell Gilbert <lgusenet@be-well.ilk.org> - 2014-03-26 13:31 -0400
    Re: Is goto Still Considered Harmful? gazelle@shell.xmission.com (Kenny McCormack) - 2014-03-24 16:31 +0000
    Re: Is goto Still Considered Harmful? "BartC" <bc@freeuk.com> - 2014-03-24 16:46 +0000
      Re: Is goto Still Considered Harmful? John Bode <jfbode1029@gmail.com> - 2014-03-24 16:10 -0700
        Re: Is goto Still Considered Harmful? Keith Thompson <kst-u@mib.org> - 2014-03-24 17:19 -0700
          Re: Is goto Still Considered Harmful? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-03-25 02:56 -0700
          Re: Is goto Still Considered Harmful? Keith Thompson <kst-u@mib.org> - 2014-03-25 07:34 -0700
            Re: Is goto Still Considered Harmful? James Kuyper <jameskuyper@verizon.net> - 2014-03-25 10:57 -0400
              Re: Is goto Still Considered Harmful? gazelle@shell.xmission.com (Kenny McCormack) - 2014-03-25 16:09 +0000
              Re: Is goto Still Considered Harmful? Kaz Kylheku <kaz@kylheku.com> - 2014-03-25 16:14 +0000
                Re: Is goto Still Considered Harmful? Ian Collins <ian-news@hotmail.com> - 2014-03-26 08:06 +1300
                Re: Is goto Still Considered Harmful? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-03-25 12:49 -0700
                Re: Is goto Still Considered Harmful? Stephen Sprunk <stephen@sprunk.org> - 2014-03-31 14:05 -0500
                Re: Is goto Still Considered Harmful? James Kuyper <jameskuyper@verizon.net> - 2014-03-31 15:20 -0400
                Re: Is goto Still Considered Harmful? Stephen Sprunk <stephen@sprunk.org> - 2014-04-04 14:56 -0500
                Re: Is goto Still Considered Harmful? James Kuyper <jameskuyper@verizon.net> - 2014-04-04 17:11 -0400
                Re: Is goto Still Considered Harmful? Ian Collins <ian-news@hotmail.com> - 2014-04-05 12:03 +1300
                Re: Is goto Still Considered Harmful? ralph <nt_consulting@yahoo.com> - 2014-04-05 00:17 -0500
                Re: Is goto Still Considered Harmful? Ian Collins <ian-news@hotmail.com> - 2014-04-05 20:14 +1300
                Re: Is goto Still Considered Harmful? Stephen Sprunk <stephen@sprunk.org> - 2014-04-09 14:30 -0500
                Re: Is goto Still Considered Harmful? James Kuyper <jameskuyper@verizon.net> - 2014-04-09 16:37 -0400
                Re: Is goto Still Considered Harmful? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-04-09 14:01 -0700
                Re: Is goto Still Considered Harmful? Richard <rgrdev_@gmail.com> - 2014-04-05 15:21 +0100
                Re: Is goto Still Considered Harmful? Ian Collins <ian-news@hotmail.com> - 2014-04-01 11:04 +1300
                Re: Is goto Still Considered Harmful? Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2014-04-01 02:45 +0300
                Re: Is goto Still Considered Harmful? Ian Collins <ian-news@hotmail.com> - 2014-04-01 13:03 +1300
                Re: Is goto Still Considered Harmful? Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2014-05-22 12:01 +0300
                Re: Is goto Still Considered Harmful? Ian Collins <ian-news@hotmail.com> - 2014-05-22 21:22 +1200
                Re: Is goto Still Considered Harmful? Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2014-05-22 11:53 +0300
              Re: Is goto Still Considered Harmful? James Kuyper <jameskuyper@verizon.net> - 2014-03-31 12:10 -0400
                Re: Is goto Still Considered Harmful? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-03-31 10:39 -0700
                Re: Is goto Still Considered Harmful? Stephen Sprunk <stephen@sprunk.org> - 2014-03-31 13:42 -0500
                Re: Is goto Still Considered Harmful? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-03-31 15:16 -0700
                Re: Is goto Still Considered Harmful? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-04-01 00:24 -0700
                Re: Is goto Still Considered Harmful? Richard Damon <Richard@Damon-Family.org> - 2014-04-01 08:26 -0400
                Re: Is goto Still Considered Harmful? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-04-01 06:50 -0700
                Re: Are setters Stil Considered Harmful? (was: Is goto Still Considered Harmful?) Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-04-02 10:49 -0700
            Re: Is goto Still Considered Harmful? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-03-25 19:30 +0000
              Re: Is goto Still Considered Harmful? Ken Brody <kenbrody@spamcop.net> - 2014-03-27 09:33 -0400
            Re: Is goto Still Considered Harmful? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-03-25 19:37 +0000
        Re: Is goto Still Considered Harmful? James Kuyper <jameskuyper@verizon.net> - 2014-03-25 00:30 -0400
        Re: Is goto Still Considered Harmful? John Bode <jfbode1029@gmail.com> - 2014-03-27 11:47 -0700
          Re: Is goto Still Considered Harmful? James Kuyper <jameskuyper@verizon.net> - 2014-03-27 20:39 -0400
            Re: Is goto Still Considered Harmful? gazelle@shell.xmission.com (Kenny McCormack) - 2014-03-28 01:40 +0000
          Re: Is goto Still Considered Harmful? Richard <rgrdev_@gmail.com> - 2014-03-28 10:09 +0100
            Re: Is goto Still Considered Harmful? gazelle@shell.xmission.com (Kenny McCormack) - 2014-03-28 09:48 +0000
            Re: Is goto Still Considered Harmful? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-03-28 03:24 -0700
              Re: Is goto Still Considered Harmful? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-03-28 18:52 +0000
              Re: Is goto Still Considered Harmful? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-03-30 02:45 -0700
    Re: Is goto Still Considered Harmful? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-03-24 12:53 -0700
    Re: Is goto Still Considered Harmful? John Bode <jfbode1029@gmail.com> - 2014-03-24 15:02 -0700
      Re: Is goto Still Considered Harmful? James Kuyper <jameskuyper@verizon.net> - 2014-03-24 19:11 -0400
  Re: Is goto Still Considered Harmful? Tim Rentsch <txr@alumni.caltech.edu> - 2014-03-29 05:56 -0700

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