Re: Am I being too C++ like?

From	Keith Thompson <kst-u@mib.org>
Newsgroups	comp.lang.c
Subject	Re: Am I being too C++ like?
Date	2012-03-08 14:19 -0800
Organization	None to speak of
Message-ID	<ln8vja4txr.fsf@nuthaus.mib.org> (permalink)
References	(3 earlier) <kfny5sn1p0y.fsf@x-alumni2.alumni.caltech.edu> <lnzkd3wirb.fsf@nuthaus.mib.org> <kfnobtjxb9g.fsf@x-alumni2.alumni.caltech.edu> <lnhazauzlw.fsf@nuthaus.mib.org> <kfnd38mstxq.fsf@x-alumni2.alumni.caltech.edu>

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Tim Rentsch <txr@alumni.caltech.edu> writes:
> Keith Thompson <kst-u@mib.org> writes:
>> Tim Rentsch <txr@alumni.caltech.edu> writes:
[...]
>>> To my way of thinking the main reason to use typedef names
>>> is to encourage use of information hiding and viewing of
>>> various entities as abstract data types.
>> [...]
>>
>> I agree that that's the main *appropriate* reason to use typedefs for
>> structs.  Unfortunately, it's not the main reason programmers actually
>> use them.
>
> But that's a reason to talk about information hiding, ADT's, and
> opaque types /more/, not to insist more strenuously that typedefs
> shouldn't be used.  If you show examples of where it's good to
> typedef a struct, that will both strengthen an understanding of
> information hiding and ADT's, etc, and also make comments about
> when /not/ to use typedefs more effective.  Always typedef'ing
> is bad;  never typedef'ing is bad.  A good developer needs to
> understand the problems of both extremes.

Ok, let me refine my stated position.

For a struct type that's not opaque, i.e., where the code that
uses the type is expected to refer to its members by name, I see
very little reason to use a typedef.  My personal preference in
such cases is to declare the type with a tag, like "struct foo",
and then consistently refer to the type as "struct foo".  The only
benefit of a typedef is to provide a one-word name for a type that
already has a two-word name.  A drawback is that, in practice,
programmers don't use consistent conventions for the tag name and
the typedef name (using the same identifier for both alleviates
that problem).  Another drawback is that you still need a tag for
self-referential types, but not for non-self-referential types,
a distinction that isn't necessary if you just use the tag.

I don't *strongly* feel that typedefs for such structs are a bad idea.
Having a one-word name for a type is of *some* benefit.  I don't mind
tha fact that C++ in effect does this for you.

For a type that's truly opaque, i.e., where the code that uses it never
refers to members by name, a typedef is appropriate.  In such cases,
having to refer to the type as "struct foo" unnecessarily leaks
information: client code shouldn't have to care that the type is a
struct.  You should be able to change the type from a struct to an
integer without breaking client code.  The type FILE in <stdio.h>
is a good example of this.

But I find that the former case is much more common than the latter.

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
    Will write code for food.
"We must do something.  This is something.  Therefore, we must do this."
    -- Antony Jay and Jonathan Lynn, "Yes Minister"

Thread

Am I being too C++ like? nroberts <roberts.noah@gmail.com> - 2012-01-18 13:53 -0800
  Re: Am I being too C++ like? Shao Miller <sha0.miller@gmail.com> - 2012-01-18 18:50 -0500
    Re: Am I being too C++ like? Nobody <nobody@nowhere.com> - 2012-01-19 04:13 +0000
    Re: Am I being too C++ like? ImpalerCore <jadill33@gmail.com> - 2012-01-19 09:09 -0800
  Re: Am I being too C++ like? Philip Lantz <prl@canterey.us> - 2012-01-18 21:42 -0800
  Re: Am I being too C++ like? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-01-19 12:30 +0000
    Re: Am I being too C++ like? "BartC" <bc@freeuk.com> - 2012-01-19 15:17 +0000
      Re: Am I being too C++ like? Keith Thompson <kst-u@mib.org> - 2012-01-19 18:44 -0800
        Re: Am I being too C++ like? "BartC" <bc@freeuk.com> - 2012-01-20 13:44 +0000
          Re: Am I being too C++ like? Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-01-20 09:08 -0500
            Re: Am I being too C++ like? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-01-20 07:58 -0800
            Re: Am I being too C++ like? Keith Thompson <kst-u@mib.org> - 2012-01-20 11:25 -0800
            Re: Am I being too C++ like? Kleuske <kleuske@nowhere.net> - 2012-01-20 20:17 +0000
              Re: Am I being too C++ like? Ian Collins <ian-news@hotmail.com> - 2012-01-21 09:23 +1300
                Re: Am I being too C++ like? Kleuske <kleuske@nowhere.net> - 2012-01-20 22:00 +0000
                Re: Am I being too C++ like? Stephen Sprunk <stephen@sprunk.org> - 2012-01-20 16:28 -0600
                Re: Am I being too C++ like? Ian Collins <ian-news@hotmail.com> - 2012-01-21 11:43 +1300
                Re: Am I being too C++ like? Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-01-20 18:02 -0500
                Re: Am I being too C++ like? Keith Thompson <kst-u@mib.org> - 2012-01-20 16:12 -0800
                Re: Am I being too C++ like? Kaz Kylheku <kaz@kylheku.com> - 2012-01-21 00:13 +0000
                Re: Am I being too C++ like? William Ahern <william@wilbur.25thandClement.com> - 2012-01-20 17:37 -0800
                Re: Am I being too C++ like? Keith Thompson <kst-u@mib.org> - 2012-01-20 22:25 -0800
                Re: Am I being too C++ like? gazelle@shell.xmission.com (Kenny McCormack) - 2012-01-21 16:07 +0000
                Re: Am I being too C++ like? Bill Reid <hormelfree@gmail.com> - 2012-01-23 17:26 -0800
                Re: Am I being too C++ like? Kaz Kylheku <kaz@kylheku.com> - 2012-01-21 18:00 +0000
                Re: Am I being too C++ like? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-01-21 21:25 +0000
                Re: Am I being too C++ like? Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2012-02-11 23:46 +0200
                Re: Am I being too C++ like? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-02-11 22:56 +0000
                Re: Am I being too C++ like? Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2012-02-22 02:34 +0200
                Re: Am I being too C++ like? Jens Gustedt <jens.gustedt@loria.fr> - 2012-01-21 22:42 +0100
                Re: Am I being too C++ like? James Kuyper <jameskuyper@verizon.net> - 2012-01-21 21:22 -0500
                Re: Am I being too C++ like? Jens Gustedt <jens.gustedt@loria.fr> - 2012-01-22 14:56 +0100
                Re: Am I being too C++ like? Ian Collins <ian-news@hotmail.com> - 2012-01-22 10:29 +1300
                Re: Am I being too C++ like? Kleuske <kleuske@nowhere.net> - 2012-01-21 11:36 +0000
              Re: Am I being too C++ like? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-01-22 12:13 +0000
                Re: Am I being too C++ like? Kleuske <kleuske@nowhere.net> - 2012-01-22 12:39 +0000
                Re: Am I being too C++ like? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-01-23 23:45 +0000
                Re: Am I being too C++ like? Kleuske <kleuske@nowhere.net> - 2012-01-24 16:54 +0000
            Re: Am I being too C++ like? Nick Keighley <nick_keighley_nospam@hotmail.com> - 2012-01-22 04:43 -0800
              Re: Am I being too C++ like? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-01-22 15:29 +0000
          Re: Am I being too C++ like? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-01-21 11:58 +0000
          Re: Am I being too C++ like? Seebs <usenet-nospam@seebs.net> - 2012-01-21 21:32 +0000
  Re: Am I being too C++ like? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-01-19 04:23 -0800
    Re: Am I being too C++ like? Rui Maciel <rui.maciel@gmail.com> - 2012-01-19 14:39 +0000
    Re: Am I being too C++ like? Nick Keighley <nick_keighley_nospam@hotmail.com> - 2012-01-22 05:14 -0800
      Re: Am I being too C++ like? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-01-23 23:42 +0000
  Re: Am I being too C++ like? Rui Maciel <rui.maciel@gmail.com> - 2012-01-19 14:51 +0000
  Re: Am I being too C++ like? jgk@panix.com (Joe keane) - 2012-01-19 23:04 +0000
  Re: Am I being too C++ like? Ian Collins <ian-news@hotmail.com> - 2012-01-20 16:03 +1300
    Re: Am I being too C++ like? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-01-20 06:01 -0800
      Re: Am I being too C++ like? Ian Collins <ian-news@hotmail.com> - 2012-01-21 08:03 +1300
        Re: Am I being too C++ like? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-01-21 12:31 -0800
          Re: Am I being too C++ like? Ian Collins <ian-news@hotmail.com> - 2012-01-22 10:18 +1300
  Re: Am I being too C++ like? cri@tiac.net (Richard Harter) - 2012-01-20 05:22 +0000
  Re: Am I being too C++ like? Marco <prenom_nomus@yahoo.com> - 2012-01-21 07:29 -0800
    Re: Am I being too C++ like? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-01-24 12:13 +0000
      Re: Am I being too C++ like? Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-31 14:32 -0800
        Re: Am I being too C++ like? Keith Thompson <kst-u@mib.org> - 2012-01-31 15:32 -0800
          Re: Am I being too C++ like? Keith Thompson <kst-u@mib.org> - 2012-01-31 19:46 -0800
          Re: Am I being too C++ like? Shao Miller <sha0.miller@gmail.com> - 2012-01-31 23:54 -0500
            Re: Am I being too C++ like? Keith Thompson <kst-u@mib.org> - 2012-01-31 22:24 -0800
          Re: Am I being too C++ like? Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-31 23:28 -0800
            Re: Am I being too C++ like? Keith Thompson <kst-u@mib.org> - 2012-02-01 11:23 -0800
              Re: Am I being too C++ like? Stephen Sprunk <stephen@sprunk.org> - 2012-02-01 15:01 -0600
                Re: Am I being too C++ like? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-02-01 14:09 -0800
                Re: Am I being too C++ like? Keith Thompson <kst-u@mib.org> - 2012-02-01 14:44 -0800
                Re: Am I being too C++ like? Shao Miller <sha0.miller@gmail.com> - 2012-02-01 17:36 -0500
              Re: Am I being too C++ like? Tim Rentsch <txr@alumni.caltech.edu> - 2012-03-08 12:45 -0800
                Re: Am I being too C++ like? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-03-08 21:41 +0000
                Re: Am I being too C++ like? Ian Collins <ian-news@hotmail.com> - 2012-03-09 17:42 +1300
                Re: Am I being too C++ like? Kaz Kylheku <kaz@kylheku.com> - 2012-03-09 08:12 +0000
                Re: Am I being too C++ like? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-03-09 12:01 +0000
                Re: Am I being too C++ like? Keith Thompson <kst-u@mib.org> - 2012-03-08 14:19 -0800
                Re: Am I being too C++ like? Tim Rentsch <txr@alumni.caltech.edu> - 2012-03-09 13:32 -0800
                Re: Am I being too C++ like? nick_keighley_nospam@hotmail.com - 2012-03-09 04:18 -0800
                Re: Am I being too C++ like? Ike Naar <ike@iceland.freeshell.org> - 2012-03-09 13:04 +0000
                Re: Am I being too C++ like? Kaz Kylheku <kaz@kylheku.com> - 2012-03-10 01:02 +0000
                Re: Am I being too C++ like? Ike Naar <ike@iceland.freeshell.org> - 2012-03-10 07:59 +0000
                Re: Am I being too C++ like? Ian Collins <ian-news@hotmail.com> - 2012-03-10 21:17 +1300
                Re: Am I being too C++ like? nick_keighley_nospam@hotmail.com - 2012-03-10 02:39 -0800
                Re: Am I being too C++ like? Tim Rentsch <txr@alumni.caltech.edu> - 2012-03-09 13:51 -0800
                Re: Am I being too C++ like? nick_keighley_nospam@hotmail.com - 2012-03-10 02:54 -0800
            Re: Am I being too C++ like? Ian Collins <ian-news@hotmail.com> - 2012-03-10 12:27 +1300
          Re: Am I being too C++ like? Rui Maciel <rui.maciel@gmail.com> - 2012-02-01 07:41 +0000
            Re: Am I being too C++ like? Keith Thompson <kst-u@mib.org> - 2012-02-01 11:24 -0800
        Re: Am I being too C++ like? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-02-01 21:55 +0000

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