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Groups > comp.lang.c++ > #8728

Re: maximum cases in a switch ?

From Lynn McGuire <lmc@winsim.com>
Newsgroups comp.lang.c++
Subject Re: maximum cases in a switch ?
Date 2011-08-12 10:58 -0500
Organization A noiseless patient Spider
Message-ID <j23ilq$3ro$1@dont-email.me> (permalink)
References (3 earlier) <Xns9F3D5912E1A36jgreerdoubletakecom@88.198.244.100> <j1tvu8$lu6$1@dont-email.me> <Xns9F3E59BF6EBC4jgreerdoubletakecom@88.198.244.100> <j20tlv$una$1@dont-email.me> <Xns9F3F635C0B26Ajgreerdoubletakecom@88.198.244.100>

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On 8/12/2011 8:46 AM, Joe Greer wrote:
> Lynn McGuire<lmc@winsim.com>  wrote in news:j20tlv$una$1@dont-email.me:
>
>>
>>      /*  GenGroup - base group  */
>> #define  GEN_COM           0
>> #define  GEN_COMNAM        1
>> #define  GEN_COMFOR        2
>> ...
>> #define  GEN_CALVAPPRE        205
>>
>> Lynn
>>
>
> Since these do seem to be mostly sequential, then an array lookup seems appropriate.  The next
> question then seems to be, does it make more sense to do what I first suggested (array of pointers)
> or does it make more sense to just have an array of DataDescriptors and do away with the variables
> aDD_GEN_CALVAPPRE etc entirely.  e.g.
>
>
> static DataDescriptor descriptors[] =
> {
>   { /* whatever is in a DataDescriptor */ },
>   { /* whetever is in a DataDescriptor */ },
> .
> .
> }
>
> and just return the address of the element. i.e.  return&descriptors[aSymbol];
>
> Of course, that only works if DataDescriptor is POD, otherwise you need to construct objects in there
> and do other object lifetime management.
>
> joe

What is POD ?  The data descriptors live the lifetime of
the app and are built at compile time to save runtime.
"Performance is a Feature" applies to all software:
    http://www.codinghorror.com/blog/2011/06/performance-is-a-feature.html

I gained 100X in speed when I converted my app from
smalltalk to C++ and do not intend to give it back over
some language semantics.  Besides that, the data descriptors
are contained in almost 100 classes (this particular class
is the biggest at 525) and changing this code would be
un-needful.

Please note that I got my original question answered and
I really appreciate that.  It means that my current data
storage descriptor design is extensible and that meets my
needs for now.

Thanks,
Lynn

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Thread

maximum cases in a switch ? Lynn McGuire <lmc@winsim.com> - 2011-08-09 11:03 -0500
  Re: maximum cases in a switch ? LR <lruss@superlink.net> - 2011-08-09 12:27 -0400
    Re: maximum cases in a switch ? Lynn McGuire <lmc@winsim.com> - 2011-08-09 12:23 -0500
      Re: maximum cases in a switch ? Joe Greer <jgreer@doubletake.com> - 2011-08-10 12:45 +0000
        Re: maximum cases in a switch ? Victor Bazarov <v.bazarov@comcast.invalid> - 2011-08-10 09:09 -0400
          Re: maximum cases in a switch ? Joe Greer <jgreer@doubletake.com> - 2011-08-11 12:49 +0000
            Re: maximum cases in a switch ? Lynn McGuire <lmc@winsim.com> - 2011-08-11 10:48 -0500
              Re: maximum cases in a switch ? Alain Ketterlin <alain@dpt-info.u-strasbg.fr> - 2011-08-11 18:26 +0200
                Re: maximum cases in a switch ? Lynn McGuire <lmc@winsim.com> - 2011-08-11 11:45 -0500
                Re: maximum cases in a switch ? Alain Ketterlin <alain@dpt-info.u-strasbg.fr> - 2011-08-11 20:06 +0200
                Re: maximum cases in a switch ? Lynn McGuire <lmc@winsim.com> - 2011-08-11 14:47 -0500
                Re: maximum cases in a switch ? Alain Ketterlin <alain@dpt-info.u-strasbg.fr> - 2011-08-11 22:32 +0200
                Re: maximum cases in a switch ? gwowen <gwowen@gmail.com> - 2011-08-12 06:00 -0700
                Re: maximum cases in a switch ? Lynn McGuire <lmc@winsim.com> - 2011-08-12 10:49 -0500
              Re: maximum cases in a switch ? Joe Greer <jgreer@doubletake.com> - 2011-08-12 13:46 +0000
                Re: maximum cases in a switch ? Lynn McGuire <lmc@winsim.com> - 2011-08-12 10:58 -0500
                Re: maximum cases in a switch ? Joe Greer <jgreer@doubletake.com> - 2011-08-12 20:22 +0000
                Re: maximum cases in a switch ? Lynn McGuire <lmc@winsim.com> - 2011-08-12 15:57 -0500
                Re: maximum cases in a switch ? Leo Equinox Gaspard <ekinox1995@gmail.com> - 2011-08-13 20:58 +0200
                Re: maximum cases in a switch ? Victor Bazarov <v.bazarov@comcast.invalid> - 2011-08-13 18:16 -0400
                Re: maximum cases in a switch ? Leo Equinox Gaspard <ekinox1995@gmail.com> - 2011-08-16 07:55 +0200
                Re: maximum cases in a switch ? Victor Bazarov <v.bazarov@comcast.invalid> - 2011-08-16 09:04 -0400
                Re: maximum cases in a switch ? Leo Equinox Gaspard <ekinox1995@gmail.com> - 2011-08-17 00:11 +0200
                Re: maximum cases in a switch ? Ian Collins <ian-news@hotmail.com> - 2011-08-17 10:24 +1200
                Re: maximum cases in a switch ? Leo Equinox Gaspard <ekinox1995@gmail.com> - 2011-08-17 01:33 +0200
                Re: maximum cases in a switch ? Leo Equinox Gaspard <ekinox1995@gmail.com> - 2011-08-17 00:18 +0200
                Re: maximum cases in a switch ? Ian Collins <ian-news@hotmail.com> - 2011-08-17 10:29 +1200
                Re: maximum cases in a switch ? Leo Equinox Gaspard <ekinox1995@gmail.com> - 2011-08-17 01:37 +0200
                Re: maximum cases in a switch ? Ian Collins <ian-news@hotmail.com> - 2011-08-17 12:02 +1200
  Re: maximum cases in a switch ? Juha Nieminen <nospam@thanks.invalid> - 2011-08-09 16:38 +0000
  Re: maximum cases in a switch ? Victor Bazarov <v.bazarov@comcast.invalid> - 2011-08-09 15:42 -0400
    Re: maximum cases in a switch ? Lynn McGuire <lmc@winsim.com> - 2011-08-09 15:39 -0500
      Re: maximum cases in a switch ? Leo Equinox Gaspard <ekinox1995@gmail.com> - 2011-08-09 23:39 +0200
        Re: maximum cases in a switch ? Lynn McGuire <lmc@winsim.com> - 2011-08-09 17:18 -0500
      Re: maximum cases in a switch ? Victor Bazarov <v.bazarov@comcast.invalid> - 2011-08-09 20:06 -0400
        Re: maximum cases in a switch ? Juha Nieminen <nospam@thanks.invalid> - 2011-08-10 06:54 +0000
          Re: maximum cases in a switch ? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2011-08-10 12:20 +0000
            Re: maximum cases in a switch ? Lynn McGuire <lmc@winsim.com> - 2011-08-10 11:34 -0500
              Re: maximum cases in a switch ? Paul Brettschneider <paul.brettschneider@yahoo.fr> - 2011-08-10 20:34 +0200
                Re: maximum cases in a switch ? Paul Brettschneider <paul.brettschneider@yahoo.fr> - 2011-08-10 21:06 +0200
              Re: maximum cases in a switch ? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2011-08-11 21:00 +0000
      Re: maximum cases in a switch ? Marcel Müller <news.5.maazl@spamgourmet.com> - 2011-08-10 11:10 +0200
        Re: maximum cases in a switch ? Juha Nieminen <nospam@thanks.invalid> - 2011-08-10 10:40 +0000
          Re: maximum cases in a switch ? Victor Bazarov <v.bazarov@comcast.invalid> - 2011-08-10 09:02 -0400
            Re: maximum cases in a switch ? Juha Nieminen <nospam@thanks.invalid> - 2011-08-11 08:05 +0000
          Re: maximum cases in a switch ? Marcel Müller <news.5.maazl@spamgourmet.com> - 2011-08-10 21:17 +0200
        Re: maximum cases in a switch ? Lynn McGuire <lmc@winsim.com> - 2011-08-10 11:12 -0500
          Re: maximum cases in a switch ? "Paul" <pchristor@yahoo.co.uk> - 2011-08-11 11:07 +0100
            Re: maximum cases in a switch ? Leigh Johnston <leigh@i42.co.uk> - 2011-08-13 00:14 +0100
              Re: maximum cases in a switch ? "Paul" <pchristor@yahoo.co.uk> - 2011-08-13 14:54 +0100
                Re: maximum cases in a switch ? Leigh Johnston <leigh@i42.co.uk> - 2011-08-13 15:26 +0100
                Re: maximum cases in a switch ? Juha Nieminen <nospam@thanks.invalid> - 2011-08-14 18:14 +0000
                Re: maximum cases in a switch ? "Paul" <pchristor@yahoo.co.uk> - 2011-08-15 01:09 +0100
                Re: maximum cases in a switch ? Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-08-15 02:15 -0700
                Re: maximum cases in a switch ? "Paul" <pchristor@yahoo.co.uk> - 2011-08-15 12:18 +0100
                Re: maximum cases in a switch ? Leigh Johnston <leigh@i42.co.uk> - 2011-08-15 13:22 +0100
                Re: maximum cases in a switch ? "Paul" <pchristor@yahoo.co.uk> - 2011-08-15 13:38 +0100
                Re: maximum cases in a switch ? Leigh Johnston <leigh@i42.co.uk> - 2011-08-15 14:06 +0100
                Re: maximum cases in a switch ? "Paul" <pchristor@yahoo.co.uk> - 2011-08-15 16:05 +0100
                Re: maximum cases in a switch ? Leigh Johnston <leigh@i42.co.uk> - 2011-08-15 16:20 +0100
                Re: maximum cases in a switch ? "Paul" <pchristor@yahoo.co.uk> - 2011-08-15 20:24 +0100
                Re: maximum cases in a switch ? Leigh Johnston <leigh@i42.co.uk> - 2011-08-15 22:09 +0100
                Re: maximum cases in a switch ? Leigh Johnston <leigh@i42.co.uk> - 2011-08-15 22:19 +0100
                Re: maximum cases in a switch ? "Paul" <pchristor@yahoo.co.uk> - 2011-08-16 03:10 +0100
                Re: maximum cases in a switch ? Leigh Johnston <leigh@i42.co.uk> - 2011-08-16 13:08 +0100
                Re: maximum cases in a switch ? "Paul" <pchristor@yahoo.co.uk> - 2011-08-16 14:01 +0100
                Re: maximum cases in a switch ? Leigh Johnston <leigh@i42.co.uk> - 2011-08-16 14:10 +0100
                Re: maximum cases in a switch ? "Paul" <pchristor@yahoo.co.uk> - 2011-08-16 03:07 +0100
                Re: maximum cases in a switch ? Leigh Johnston <leigh@i42.co.uk> - 2011-08-16 13:05 +0100
                Re: maximum cases in a switch ? "Paul" <pchristor@yahoo.co.uk> - 2011-08-16 13:57 +0100
                Re: maximum cases in a switch ? Leigh Johnston <leigh@i42.co.uk> - 2011-08-16 14:07 +0100
                Re: maximum cases in a switch ? "Paul" <pchristor@yahoo.co.uk> - 2011-08-16 19:29 +0100
                Re: maximum cases in a switch ? Leigh Johnston <leigh@i42.co.uk> - 2011-08-16 19:35 +0100
                Re: maximum cases in a switch ? "Paul" <pchristor@yahoo.co.uk> - 2011-08-17 00:01 +0100
                Re: maximum cases in a switch ? Leigh Johnston <leigh@i42.co.uk> - 2011-08-17 00:11 +0100
                Re: maximum cases in a switch ? "Paul" <pchristor@yahoo.co.uk> - 2011-08-17 01:23 +0100
                Re: maximum cases in a switch ? Juha Nieminen <nospam@thanks.invalid> - 2011-08-15 13:32 +0000
                Re: maximum cases in a switch ? "Paul" <pchristor@yahoo.co.uk> - 2011-08-15 15:20 +0100
                Re: maximum cases in a switch ? Leigh Johnston <leigh@i42.co.uk> - 2011-08-15 15:33 +0100
                Re: maximum cases in a switch ? Juha Nieminen <nospam@thanks.invalid> - 2011-08-16 07:34 +0000
                Re: maximum cases in a switch ? "Paul" <pchristor@yahoo.co.uk> - 2011-08-16 13:49 +0100
                Re: maximum cases in a switch ? Juha Nieminen <nospam@thanks.invalid> - 2011-08-16 15:02 +0000
                Re: maximum cases in a switch ? Leigh Johnston <leigh@i42.co.uk> - 2011-08-16 16:07 +0100
                Re: maximum cases in a switch ? "Paul" <pchristor@yahoo.co.uk> - 2011-08-16 19:50 +0100
                Re: maximum cases in a switch ? Leigh Johnston <leigh@i42.co.uk> - 2011-08-16 19:57 +0100
                Re: maximum cases in a switch ? "Paul" <pchristor@yahoo.co.uk> - 2011-08-17 00:12 +0100
                Re: maximum cases in a switch ? "Paul" <pchristor@yahoo.co.uk> - 2011-08-16 19:34 +0100
                Re: maximum cases in a switch ? Juha Nieminen <nospam@thanks.invalid> - 2011-08-17 12:55 +0000
                Re: maximum cases in a switch ? "Paul" <pchristor@yahoo.co.uk> - 2011-08-17 14:32 +0100
                Re: maximum cases in a switch ? Juha Nieminen <nospam@thanks.invalid> - 2011-08-17 20:11 +0000
                Re: maximum cases in a switch ? "Paul" <pchristor@yahoo.co.uk> - 2011-08-18 11:00 +0100
                Re: maximum cases in a switch ? Joshua Maurice <joshuamaurice@gmail.com> - 2011-08-15 15:35 -0700
                Re: maximum cases in a switch ? Gareth Owen <gwowen@gmail.com> - 2011-08-17 06:34 +0100
                Re: maximum cases in a switch ? "Paul" <pchristor@yahoo.co.uk> - 2011-08-17 12:23 +0100
                Re: maximum cases in a switch ? Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-08-17 02:01 -0700
                Re: maximum cases in a switch ? "Paul" <pchristor@yahoo.co.uk> - 2011-08-17 12:29 +0100
                Re: maximum cases in a switch ? Leigh Johnston <leigh@i42.co.uk> - 2011-08-17 14:13 +0100
                Re: maximum cases in a switch ? "Paul" <pchristor@yahoo.co.uk> - 2011-08-17 14:18 +0100
                Re: maximum cases in a switch ? Leigh Johnston <leigh@i42.co.uk> - 2011-08-17 14:43 +0100
                Re: maximum cases in a switch ? "Paul" <pchristor@yahoo.co.uk> - 2011-08-17 15:23 +0100
                Re: maximum cases in a switch ? Leigh Johnston <leigh@i42.co.uk> - 2011-08-17 15:31 +0100
                Re: maximum cases in a switch ? "Paul" <pchristor@yahoo.co.uk> - 2011-08-17 15:48 +0100
                Re: maximum cases in a switch ? Leigh Johnston <leigh@i42.co.uk> - 2011-08-17 15:53 +0100
                Re: maximum cases in a switch ? SG <s.gesemann@gmail.com> - 2011-08-17 07:54 -0700
                Re: maximum cases in a switch ? "Paul" <pchristor@yahoo.co.uk> - 2011-08-17 20:40 +0100
                Re: maximum cases in a switch ? Larry Evans <cppljevans@suddenlink.net> - 2011-08-17 10:54 -0500
                Re: maximum cases in a switch ? Robert Wessel <robertwessel2@yahoo.com> - 2011-08-17 12:44 -0500
                jump table vs. vector of function pointers(was Re: maximum cases in a switch ? Larry Evans <cppljevans@suddenlink.net> - 2011-08-17 15:18 -0500
                Re: jump table vs. vector of function pointers(was Re: maximum cases in a switch ? Alain Ketterlin <alain@dpt-info.u-strasbg.fr> - 2011-08-17 22:48 +0200
                Re: jump table vs. vector of function pointers(was Re: maximum cases in a switch ? Larry Evans <cppljevans@suddenlink.net> - 2011-08-17 16:49 -0500
                Re: maximum cases in a switch ? Thomas David Rivers <rivers@dignus.com> - 2011-08-17 13:50 -0400
                Re: maximum cases in a switch ? "Paul" <pchristor@yahoo.co.uk> - 2011-08-17 22:04 +0100
                Re: maximum cases in a switch ? Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-08-22 03:23 -0700
    Re: maximum cases in a switch ? Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-08-12 05:51 -0700
      Re: maximum cases in a switch ? Victor Bazarov <v.bazarov@comcast.invalid> - 2011-08-13 08:45 -0400
    Re: maximum cases in a switch ? James Kanze <james.kanze@gmail.com> - 2011-08-21 16:55 -0700
      Re: maximum cases in a switch ? Robert Wessel <robertwessel2@yahoo.com> - 2011-08-21 23:22 -0500
        Re: maximum cases in a switch ? Victor Bazarov <v.bazarov@comcast.invalid> - 2011-08-22 08:14 -0400
        Re: maximum cases in a switch ? James Kanze <james.kanze@gmail.com> - 2011-08-22 10:56 -0700

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