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Re: Non-constant initializers

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On Sat, May 14, 2011 at 02:30:58PM -0500, Shao Miller wrote:
> On 5/14/2011 12:59 PM, Uncle Steve wrote:
> >On Thu, May 12, 2011 at 06:53:02PM -0500, Shao Miller wrote:
> >>Are you the same person as "Fred the Freshwater Catfish"?  Or are you
> >>another person who also wishes to accomplish this type of thing?
> >
> >Apparently I've been caught out.  Now my stalkers will know that I
> >secretly lurk in c.l.c. occasionally.
> >
> 
> If you are, that doesn't bother me. :)  I was merely confirming as I 
> found the use of different posting names slightly confusing.  So getting 
> back to the C...

Right.
 
> >>>I'm looking to seed a few critical global variables with
> >>>run-time computed values.  Obviously, this will be the product of a
> >>>function call.  I would like to declare:
> >>>
> >>>int foops[] = howmuchfoo(void);
> >>>
> >>>and have everything work as I expect...
> >>
> >>Some more questions:
> >>
> >>- When do you wish this initialization to occur?  Prior to main()?
> >
> >In a perfect world.
> >
> 
> Ok.  So now: Why?  (Please see next response.)

> >>- Could you employ and enjoy an init() function which would initialize
> >>these objects, then make that the first call inside main()?
> >>
> 
> No answer to this one?  If the very first thing main() does is to call 
> an init() which populates your globals' values, then that init() makes 
> for a nicely-readable section of code to gather these items into one place.

You're making this too easy.  What could be cleaner than a variable
declaration outside of main() which also initializes it to the value it
should have before main() is called?  I'm fully aware that I can
assign a value to a variable any time I write code or macros to do it,
but there are certain kinds of application parameters, for instance,
which you may derive empirically, and assign once.  I should think
that most programmers know about these types of variables.
 
> >>- In your code example, is howmuchfoo() supposed to be returning an
> >>array of 'int' or a single 'int'?
> >
> >I don't see how that's relevant to the question.
> >
> 
> Well it's an opportunity to suggest that C functions do not return 
> arrays, as far as I know.  If howmuchfoo() was a macro that expanded to 
> an initializer list, then I believe that'd be fine.

It could do just about anything if it was a C function, couldn't it?
 
> >>- Is your request a matter of being able to read, in your code, what
> >>will be computed for an object in the immediate vicinity of the object,
> >>rather than in another place (such as an init() function)?
> >
> >That all depends on what kind of data the variables are going to hold.
> >One time, I might want to save/restore window size and positioning,
> >and in another place, the volume setting of application sounds.  It is
> >impossible to say, a priori, what variables will be used/set where, at
> >least at this stage of the design process.
> >
> 
> My question there wasn't too clear and I apologize.  What I am trying to 
> understand is why you might be inclined to avoid something like the 
> init() suggestion.  Is it a matter of:
> 
>   int saved_setting = get_saved_setting();
> 
> looking nicer, to you, at file scope, than:
> 
>   int saved_setting;
>   /* ... */
>   void init(void) {
>       saved_setting = get_saved_setting();
>       /* ...Other globals populated... */
>       return;
>     }
>   /* ... */
>   int main(void) {
>       /* Populate globals */
>       init();
>       /* ... */
>     }
> 
> ?

This is fine, and I've in fact done just that in code I've written
previously.  But see above.
 
> >>- Would you be willing to use macros to accomplish this?
> >
> >I'll think about it.
> >
> 
> Ok.  Good fortune to you. :)

I'm big on macros, but sometimes they clutter up the code with
redundant code blocks that are deader than a doornail.  Maybe the
compiler will weed them out with global CSE, maybe not.  If they
aren't in the code to begin with, they can't possibly get into the
instruction cache.



Regards,

Uncle Steve

-- 
Should a professional politician be charged with molestation if he
kisses babies while attending political rallies?

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Thread

Non-constant initializers Fred the Freshwater Catfish <usenet.fred@bdtd.invalid> - 2011-05-12 22:59 +0000
  Re: Non-constant initializers Ian Collins <ian-news@hotmail.com> - 2011-05-13 11:07 +1200
    Re: Non-constant initializers Fred the Freshwater Catfish <usenet.fred@bdtd.invalid> - 2011-05-12 23:17 +0000
      Re: Non-constant initializers Ian Collins <ian-news@hotmail.com> - 2011-05-13 11:20 +1200
        Re: Non-constant initializers Fred the Freshwater Catfish <usenet.fred@bdtd.invalid> - 2011-05-12 23:30 +0000
          Re: Non-constant initializers Ian Collins <ian-news@hotmail.com> - 2011-05-13 11:34 +1200
            Re: Non-constant initializers Keith Thompson <kst-u@mib.org> - 2011-05-12 16:52 -0700
              Re: Non-constant initializers Fred the Freshwater Catfish <usenet.fred@bdtd.invalid> - 2011-05-14 00:13 +0000
                Re: Non-constant initializers Seebs <usenet-nospam@seebs.net> - 2011-05-14 01:28 +0000
                Re: Non-constant initializers Uncle Steve <stevet810@gmail.com> - 2011-05-14 13:52 -0400
                Re: Non-constant initializers kym@kymhorsell.com - 2011-05-14 01:54 +0000
                Re: Non-constant initializers Columbus sailed the ocean China Blue <chine.bleu@yahoo.com> - 2011-05-14 01:07 -0700
                Re: Non-constant initializers kym@kymhorsell.com - 2011-05-14 09:22 +0000
                Re: Non-constant initializers Fred the Freshwater Catfish <usenet.fred@bdtd.invalid> - 2011-05-14 17:14 +0000
            Re: Non-constant initializers Fred the Freshwater Catfish <usenet.fred@bdtd.invalid> - 2011-05-14 00:11 +0000
  Re: Non-constant initializers Shao Miller <sha0.miller@gmail.com> - 2011-05-12 18:08 -0500
    Re: Non-constant initializers Uncle Steve <stevet810@gmail.com> - 2011-05-12 19:22 -0400
      Re: Non-constant initializers Shao Miller <sha0.miller@gmail.com> - 2011-05-12 18:53 -0500
        Re: Non-constant initializers Uncle Steve <stevet810@gmail.com> - 2011-05-14 13:59 -0400
          Re: Non-constant initializers Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-05-14 14:19 -0400
            Re: Non-constant initializers Shao Miller <sha0.miller@gmail.com> - 2011-05-14 15:04 -0500
            Re: Non-constant initializers Uncle Steve <stevet810@gmail.com> - 2011-05-14 15:10 -0400
              Re: Non-constant initializers James Kuyper <jameskuyper@verizon.net> - 2011-05-14 16:01 -0400
                Re: Non-constant initializers Uncle Steve <stevet810@gmail.com> - 2011-05-14 16:57 -0400
          Re: Non-constant initializers Shao Miller <sha0.miller@gmail.com> - 2011-05-14 14:30 -0500
            Re: Non-constant initializers Uncle Steve <stevet810@gmail.com> - 2011-05-14 15:25 -0400
              Re: Non-constant initializers Keith Thompson <kst-u@mib.org> - 2011-05-14 13:05 -0700
                Re: Non-constant initializers Uncle Steve <stevet810@gmail.com> - 2011-05-14 17:00 -0400
              Re: Non-constant initializers Shao Miller <sha0.miller@gmail.com> - 2011-05-14 16:14 -0500
                Re: Non-constant initializers Shao Miller <sha0.miller@gmail.com> - 2011-05-14 16:49 -0500
                Re: Non-constant initializers Uncle Steve <stevet810@gmail.com> - 2011-05-14 18:21 -0400
                Re: Non-constant initializers Shao Miller <sha0.miller@gmail.com> - 2011-05-14 21:26 -0500
                Re: Non-constant initializers Uncle Steve <stevet810@gmail.com> - 2011-05-15 14:01 -0400
              Re: Non-constant initializers Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-05-14 17:45 -0400
                Re: Non-constant initializers Uncle Steve <stevet810@gmail.com> - 2011-05-14 18:09 -0400
                Re: Non-constant initializers Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-05-15 04:01 +0100
                Re: Non-constant initializers Uncle Steve <stevet810@gmail.com> - 2011-05-15 13:26 -0400
                Re: Non-constant initializers Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-05-16 02:32 +0100
              Re: Non-constant initializers Seebs <usenet-nospam@seebs.net> - 2011-05-15 03:59 +0000
                Re: Non-constant initializers Uncle Steve <stevet810@gmail.com> - 2011-05-16 04:49 -0400
                Re: Non-constant initializers pete <pfiland@mindspring.com> - 2011-05-16 07:27 -0400
                Re: Non-constant initializers Uncle Steve <stevet810@gmail.com> - 2011-05-16 09:24 -0400
                Re: Non-constant initializers Seebs <usenet-nospam@seebs.net> - 2011-05-16 19:10 +0000
                Re: Non-constant initializers Uncle Steve <stevet810@gmail.com> - 2011-05-16 21:23 -0400
                Re: Non-constant initializers Seebs <usenet-nospam@seebs.net> - 2011-05-16 19:10 +0000
                Re: Non-constant initializers Uncle Steve <stevet810@gmail.com> - 2011-05-16 21:16 -0400
                Re: Non-constant initializers James Kuyper <jameskuyper@verizon.net> - 2011-05-16 21:37 -0400
                Re: Non-constant initializers Uncle Steve <stevet810@gmail.com> - 2011-05-16 22:42 -0400
                Re: Non-constant initializers Seebs <usenet-nospam@seebs.net> - 2011-05-17 02:40 +0000
                Re: Non-constant initializers Uncle Steve <stevet810@gmail.com> - 2011-05-16 22:50 -0400
                Re: Non-constant initializers Seebs <usenet-nospam@seebs.net> - 2011-05-17 04:14 +0000
                Re: Non-constant initializers Uncle Steve <stevet810@gmail.com> - 2011-05-17 17:37 -0400
                Re: Non-constant initializers Seebs <usenet-nospam@seebs.net> - 2011-05-17 22:22 +0000
                Re: Non-constant initializers Uncle Steve <stevet810@gmail.com> - 2011-05-17 18:33 -0400
                Re: Non-constant initializers Malcolm McLean <malcolm.mclean5@btinternet.com> - 2011-05-18 01:58 -0700
                Re: Non-constant initializers Uncle Steve <stevet810@gmail.com> - 2011-05-18 12:45 -0400
                Re: Non-constant initializers "io_x" <a@b.c.invalid> - 2011-05-18 19:30 +0200
                Re: Non-constant initializers Dr Nick <3-nospam@temporary-address.org.uk> - 2011-05-18 20:01 +0100
                Re: bug-free C code (was: Non-constant initializers) Seebs <usenet-nospam@seebs.net> - 2011-05-19 02:21 +0000
                Re: bug-free C code (was: Non-constant initializers) Keith Thompson <kst-u@mib.org> - 2011-05-18 20:00 -0700
                Re: bug-free C code (was: Non-constant initializers) Seebs <usenet-nospam@seebs.net> - 2011-05-19 03:14 +0000
                Re: bug-free C code (was: Non-constant initializers) Keith Thompson <kst-u@mib.org> - 2011-05-19 07:49 -0700
                Re: bug-free C code (was: Non-constant initializers) Seebs <usenet-nospam@seebs.net> - 2011-05-19 15:16 +0000
                Re: bug-free C code Ben Pfaff <blp@cs.stanford.edu> - 2011-05-18 20:02 -0700
                Re: bug-free C code Keith Thompson <kst-u@mib.org> - 2011-05-18 20:09 -0700
                Re: bug-free C code Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-05-18 23:24 -0400
                Re: bug-free C code Angel <angel+news@spamcop.net> - 2011-05-19 06:39 +0000
                Re: bug-free C code Keith Thompson <kst-u@mib.org> - 2011-05-19 08:05 -0700
                Re: bug-free C code Angel <angel+news@spamcop.net> - 2011-05-19 16:22 +0000
                Re: bug-free C code Keith Thompson <kst-u@mib.org> - 2011-05-19 11:36 -0700
                Re: bug-free C code Ben Pfaff <blp@cs.stanford.edu> - 2011-05-19 12:21 -0700
                Re: bug-free C code Keith Thompson <kst-u@mib.org> - 2011-05-19 13:12 -0700
                Re: bug-free C code gazelle@shell.xmission.com (Kenny McCormack) - 2011-05-19 21:52 +0000
                Re: bug-free C code Angel <angel+news@spamcop.net> - 2011-05-19 22:16 +0000
                Re: bug-free C code Shao Miller <sha0.miller@gmail.com> - 2011-05-19 17:25 -0500
                Re: bug-free C code Kenneth Brody <kenbrody@spamcop.net> - 2011-05-20 13:32 -0400
                Re: bug-free C code gazelle@shell.xmission.com (Kenny McCormack) - 2011-05-19 21:51 +0000
                Re: bug-free C code Kenneth Brody <kenbrody@spamcop.net> - 2011-05-20 13:30 -0400
                Re: bug-free C code "Joel C. Salomon" <joelcsalomon@gmail.com> - 2011-05-18 23:13 -0400
                Re: bug-free C code Dr Nick <3-nospam@temporary-address.org.uk> - 2011-05-19 08:23 +0100
      Re: Non-constant initializers Seebs <usenet-nospam@seebs.net> - 2011-05-13 00:15 +0000
      Re: Non-constant initializers "io_x" <a@b.c.invalid> - 2011-05-13 11:01 +0200
    Re: Non-constant initializers Columbus sailed the ocean China Blue <chine.bleu@yahoo.com> - 2011-05-12 16:30 -0700
  Re: Non-constant initializers Columbus sailed the ocean China Blue <chine.bleu@yahoo.com> - 2011-05-12 16:15 -0700
    Re: Non-constant initializers Fred the Freshwater Catfish <usenet.fred@bdtd.invalid> - 2011-05-12 23:28 +0000
  Re: Non-constant initializers Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2011-05-12 18:01 -0600
    Re: Non-constant initializers Keith Thompson <kst-u@mib.org> - 2011-05-12 18:15 -0700
      Re: Non-constant initializers Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2011-05-12 22:56 -0600
        Re: Non-constant initializers Seebs <usenet-nospam@seebs.net> - 2011-05-13 05:18 +0000
          Re: Non-constant initializers Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2011-05-13 09:10 -0600
            Re: Non-constant initializers Seebs <usenet-nospam@seebs.net> - 2011-05-13 20:56 +0000
      Re: Non-constant initializers Tim Rentsch <txr@alumni.caltech.edu> - 2011-05-18 23:47 -0700
        Re: Non-constant initializers Keith Thompson <kst-u@mib.org> - 2011-05-19 08:15 -0700
    Re: Non-constant initializers Fred the Freshwater Catfish <usenet.fred@bdtd.invalid> - 2011-05-13 23:57 +0000

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