Re: Which standard?

From	anton@mips.complang.tuwien.ac.at (Anton Ertl)
Newsgroups	comp.lang.forth
Subject	Re: Which standard?
Date	2012-03-31 13:46 +0000
Organization	Institut fuer Computersprachen, Technische Universitaet Wien
Message-ID	<2012Mar31.154600@mips.complang.tuwien.ac.at> (permalink)
References	<30794f7f396fa9ad7ec52f034288c527@dizum.com> <33310182.902.1332825284324.JavaMail.geo-discussion-forums@vbbdy9> <1b5d027d-8ff1-4148-9f09-c263f742846a@fk28g2000vbb.googlegroups.com> <32128823.358.1332852117878.JavaMail.geo-discussion-forums@ynjx8> <jktj8u$3ln$1@online.de>

Show all headers | View raw

Bernd Paysan <bernd.paysan@gmx.de> writes:
>Helmar Wodtke wrote:
>> As it's also bound to local variables, it breaks the "old" concept of
>> Forth how variables are defined - locals could follow this idea in a
>> theory, but that would make problems with optimizing compilers.
>
>Maybe in theory, but in practice, any optimizing compiler that is smart 
>enough to put locals into a register is easily smart enough to transform 
>all occurances of <local> @ and <local> ! into virtual register moves.  
>If there is no query of the virtual register's address left, it can go 
>to a real register.

VALUE-flavoured locals have another advantage: When they are no longer
visible, their memory can not be accessed, so it can be reused.  For
VARIABLE-flavoured locals you then have to define the lifetime of the
memory, and you can get addresses of locals that are no longer valid.

Gforth has had both flavours of locals since 1994, and
variable-flavoured locals have been used hardly, if ever.

>And the other opinion about locals (especially Anton's) is that you 
>shouldn't change it (single static assignment).  It gets its value 
>through its definition, and that's good enough.

In most cases that's the way to go, but in a few cases using TO is
preferable.  The typical case is the update of a local in an IF
branch.  So you have

... ( n ) { x }
... IF
  ... TO x ...
THEN
... x ...

If you really wanted to do this in complete single-assignment style,
you would get maybe something like:

... ( n ) { x1 }
... IF
  ... { x2 } ... x2
ELSE
  x1
THEN { x3 }
... x3 ...

That does not make things any clearer, nor do I see other advantages.

- anton
-- 
M. Anton Ertl  http://www.complang.tuwien.ac.at/anton/home.html
comp.lang.forth FAQs: http://www.complang.tuwien.ac.at/forth/faq/toc.html
     New standard: http://www.forth200x.org/forth200x.html
   EuroForth 2011: http://www.euroforth.org/ef11/

Back to comp.lang.forth | Previous | Next — Previous in thread | Next in thread | Find similar

Thread

Which standard? Nomen Nescio <nobody@dizum.com> - 2012-03-21 15:13 +0100
  Re: Which standard? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-03-21 10:37 -0500
    Re: Which standard? Nomen Nescio <nobody@dizum.com> - 2012-03-21 20:23 +0100
      Re: Which standard? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-03-22 13:34 -0500
        Re: Which standard? Nomen Nescio <nobody@dizum.com> - 2012-03-26 20:40 +0200
          Re: Which standard? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-03-26 15:00 -0500
            Re: Which standard? "Elizabeth D. Rather" <erather@forth.com> - 2012-03-26 11:18 -1000
              Re: Which standard? Bernd Paysan <bernd.paysan@gmx.de> - 2012-03-27 02:20 +0200
          Re: Which standard? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-03-27 10:10 +0000
            Re: Which standard? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-03-27 08:31 -0500
            Re: Which standard? Fritz Wuehler <fritz@spamexpire-201203.rodent.frell.theremailer.net> - 2012-03-27 17:08 +0200
              Re: Which standard? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-03-27 11:31 -0500
                Re: Which standard? Helmar Wodtke <helmwo@gmail.com> - 2012-03-27 09:35 -0700
                Re: Which standard? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-03-27 11:47 -0500
                Re: Which standard? Helmar Wodtke <helmwo@gmail.com> - 2012-03-27 10:15 -0700
                Re: Which standard? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-03-27 12:33 -0500
        Re: Which standard? Fritz Wuehler <fritz@spamexpire-201203.rodent.frell.theremailer.net> - 2012-03-26 21:00 +0200
          Re: Which standard? BruceMcF <agila61@netscape.net> - 2012-03-26 13:17 -0700
            Re: Which standard? "Elizabeth D. Rather" <erather@forth.com> - 2012-03-26 11:24 -1000
              Re: Which standard? Fritz Wuehler <fritz@spamexpire-201203.rodent.frell.theremailer.net> - 2012-03-27 17:07 +0200
          Re: Which standard? "Peter Knaggs" <pjk@bcs.org.uk> - 2012-03-27 00:54 +0100
    Re: Which standard? Hugh Aguilar <hughaguilar96@yahoo.com> - 2012-03-21 14:09 -0700
  Re: Which standard? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-03-21 15:47 +0000
    Re: Which standard? Nomen Nescio <nobody@dizum.com> - 2012-03-21 20:13 +0100
      Re: Which standard? BruceMcF <agila61@netscape.net> - 2012-03-21 15:07 -0700
      Re: Which standard? stephenXXX@mpeforth.com (Stephen Pelc) - 2012-03-22 10:14 +0000
        Re: Which standard? Nomen Nescio <nobody@dizum.com> - 2012-03-22 16:36 +0100
          Re: Which standard? "Elizabeth D. Rather" <erather@forth.com> - 2012-03-22 08:47 -1000
            Re: Which standard? Fritz Wuehler <fritz@spamexpire-201203.rodent.frell.theremailer.net> - 2012-03-23 15:19 +0100
              Re: Which standard? BruceMcF <agila61@netscape.net> - 2012-03-23 07:48 -0700
              Re: Which standard? "Peter Knaggs" <pjk@bcs.org.uk> - 2012-03-23 17:28 +0000
                Re: Which standard? Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2012-03-23 20:51 +0000
                Re: Which standard? "Peter Knaggs" <pjk@bcs.org.uk> - 2012-03-24 00:47 +0000
              Re: Which standard? "Elizabeth D. Rather" <erather@forth.com> - 2012-03-23 08:40 -1000
                Re: Which standard? Fritz Wuehler <fritz@spamexpire-201203.rodent.frell.theremailer.net> - 2012-03-26 04:42 +0200
              Re: Which standard? Bernd Paysan <bernd.paysan@gmx.de> - 2012-03-26 19:17 +0200
          Re: Which standard? Paul Rubin <no.email@nospam.invalid> - 2012-03-22 13:03 -0700
            Re: Which standard? Fritz Wuehler <fritz@spamexpire-201203.rodent.frell.theremailer.net> - 2012-03-23 19:20 +0100
          Re: Which standard? stephenXXX@mpeforth.com (Stephen Pelc) - 2012-03-22 21:15 +0000
          Re: Which standard? "Rod Pemberton" <do_not_have@noavailemail.cmm> - 2012-03-22 17:54 -0400
            Re: Which standard? "The Other Rod Pemberton" <dontaskdonttell@pemberton.it> - 2012-03-23 18:12 +0100
              Re: Which standard? "Rod Pemberton" <do_not_have@noavailemail.cmm> - 2012-03-23 20:39 -0400
                Re: Which standard? "Elizabeth D. Rather" <erather@forth.com> - 2012-03-23 16:05 -1000
                Re: Which standard? Paul Rubin <no.email@nospam.invalid> - 2012-03-23 23:11 -0700
                Re: Which standard? "A. K." <akk@nospam.org> - 2012-03-24 09:15 +0100
                Re: Which standard? "Elizabeth D. Rather" <erather@forth.com> - 2012-03-23 22:52 -1000
                Re: Which standard? "A. K." <akk@nospam.org> - 2012-03-24 10:16 +0100
                Re: Which standard? Paul Rubin <no.email@nospam.invalid> - 2012-03-24 11:25 -0700
                Re: Which standard? Mark Wills <markrobertwills@yahoo.co.uk> - 2012-03-24 04:17 -0700
                Re: Which standard? Hugh Aguilar <hughaguilar96@yahoo.com> - 2012-03-26 21:46 -0700
                Re: Which standard? Mark Wills <markrobertwills@yahoo.co.uk> - 2012-03-27 02:49 -0700
                Re: Which standard? Hugh Aguilar <hughaguilar96@yahoo.com> - 2012-03-27 22:45 -0700
              Re: Which standard? Paul Rubin <no.email@nospam.invalid> - 2012-03-23 23:06 -0700
                Re: Which standard? Fritz Wuehler <fritz@spamexpire-201203.rodent.frell.theremailer.net> - 2012-03-26 01:51 +0200
          Re: Which standard? Paul Rubin <no.email@nospam.invalid> - 2012-03-22 14:57 -0700
            Re: Which standard? Nomen Nescio <nobody@dizum.com> - 2012-03-23 12:48 +0100
      Re: Which standard? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-03-22 17:50 +0000
    Re: Which standard? Hugh Aguilar <hughaguilar96@yahoo.com> - 2012-03-21 13:37 -0700
  Re: Which standard? "Rod Pemberton" <do_not_have@noavailemail.cmm> - 2012-03-21 17:07 -0400
    Re: Which standard? Nomen Nescio <nobody@dizum.com> - 2012-03-22 09:27 +0100
      Re: Which standard? hwfwguy@gmail.com - 2012-03-22 12:06 -0700
      Re: Which standard? "Rod Pemberton" <do_not_have@noavailemail.cmm> - 2012-03-22 19:19 -0400
        Re: Which standard? Fritz Wuehler <fritz@spamexpire-201203.rodent.frell.theremailer.net> - 2012-03-23 13:02 +0100
    Re: Which standard? BruceMcF <agila61@netscape.net> - 2012-03-22 08:17 -0700
      Re: Which standard? "Elizabeth D. Rather" <erather@forth.com> - 2012-03-22 08:25 -1000
        Re: Which standard? Hans Bezemer <the.beez.speaks@gmail.com> - 2012-03-23 21:50 +0100
          Re: Which standard? "Elizabeth D. Rather" <erather@forth.com> - 2012-03-23 13:10 -1000
          Re: Which standard? Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-03-24 11:19 +0000
            Re: Which standard? "Rod Pemberton" <do_not_have@noavailemail.cmm> - 2012-03-25 07:55 -0400
              Re: Which standard? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-03-26 09:12 +0000
          Re: Which standard? Mark Wills <markrobertwills@yahoo.co.uk> - 2012-03-24 04:06 -0700
        Re: Which standard? Fritz Wuehler <fritz@spamexpire-201203.rodent.frell.theremailer.net> - 2012-03-27 21:03 +0200
  Re: Which standard? Hans Bezemer <the.beez.speaks@gmail.com> - 2012-03-21 22:28 +0100
    Re: Which standard? Hugh Aguilar <hughaguilar96@yahoo.com> - 2012-03-21 16:36 -0700
      Re: Which standard? "Rod Pemberton" <do_not_have@noavailemail.cmm> - 2012-03-22 05:15 -0400
        Re: Which standard? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-03-22 12:16 +0000
        Re: Which standard? Fritz Wuehler <fritz@spamexpire-201203.rodent.frell.theremailer.net> - 2012-03-23 01:26 +0100
          Re: Which standard? "Elizabeth D. Rather" <erather@forth.com> - 2012-03-22 15:37 -1000
            Re: Which standard? Fritz Wuehler <fritz@spamexpire-201203.rodent.frell.theremailer.net> - 2012-03-25 22:24 +0200
            Re: Which standard? "Peter Knaggs" <pjk@bcs.org.uk> - 2012-03-26 10:49 +0100
        Re: Which standard? Hans Bezemer <the.beez.speaks@gmail.com> - 2012-03-23 20:00 +0100
          Re: Which standard? "Rod Pemberton" <do_not_have@noavailemail.cmm> - 2012-03-23 21:21 -0400
            Re: Which standard? Hans Bezemer <the.beez.speaks@gmail.com> - 2012-03-24 11:44 +0100
              Re: Which standard? Bernd Paysan <bernd.paysan@gmx.de> - 2012-03-26 18:51 +0200
        Re: Which standard? Hans Bezemer <the.beez.speaks@gmail.com> - 2012-03-23 22:16 +0100
          Re: Which standard? "Elizabeth D. Rather" <erather@forth.com> - 2012-03-23 13:21 -1000
            Re: Which standard? Hans Bezemer <the.beez.speaks@gmail.com> - 2012-03-24 01:33 +0100
              Re: Which standard? "Elizabeth D. Rather" <erather@forth.com> - 2012-03-23 16:06 -1000
                Re: Which standard? Hans Bezemer <the.beez.speaks@gmail.com> - 2012-03-24 11:44 +0100
              Re: Which standard? Jan Coombs <jan_2011-02@murray-microft.co.uk> - 2012-03-24 10:08 +0000
                Re: Which standard? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-03-24 14:31 +0000
          Re: Which standard? "Rod Pemberton" <do_not_have@noavailemail.cmm> - 2012-03-23 21:24 -0400
            Re: Which standard? Hans Bezemer <the.beez.speaks@gmail.com> - 2012-03-24 11:54 +0100
              Re: Which standard? "Rod Pemberton" <do_not_have@noavailemail.cmm> - 2012-03-24 17:25 -0400
                Re: Which standard? "Elizabeth D. Rather" <erather@forth.com> - 2012-03-24 13:43 -1000
                Re: Which standard? Hans Bezemer <the.beez.speaks@gmail.com> - 2012-03-25 01:43 +0100
                Re: Which standard? "Elizabeth D. Rather" <erather@forth.com> - 2012-03-24 15:56 -1000
                Re: Which standard? Hans Bezemer <the.beez.speaks@gmail.com> - 2012-03-25 22:49 +0200
                Re: Which standard? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-03-26 09:50 +0000
                Re: Which standard? "Peter Knaggs" <pjk@bcs.org.uk> - 2012-03-25 09:18 +0100
                Re: Which standard? "Rod Pemberton" <do_not_have@noavailemail.cmm> - 2012-03-25 06:07 -0400
                Re: Which standard? Hans Bezemer <the.beez.speaks@gmail.com> - 2012-03-25 22:42 +0200
                Re: Which standard? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-03-26 09:04 +0000
                Re: Which standard? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-03-26 04:39 -0500
                Re: Which standard? Hugh Aguilar <hughaguilar96@yahoo.com> - 2012-03-26 22:29 -0700
                Re: Which standard? Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-03-26 18:09 +0000
                Re: Which standard? BruceMcF <agila61@netscape.net> - 2012-03-26 11:37 -0700
                Re: Which standard? "A. K." <akk@nospam.org> - 2012-03-26 20:49 +0200
                Re: Which standard? BruceMcF <agila61@netscape.net> - 2012-03-26 13:22 -0700
                Re: Which standard? Helmar Wodtke <helmwo@gmail.com> - 2012-03-26 11:20 -0700
                Re: Which standard? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-03-27 11:59 +0000
                Re: Which standard? Helmar Wodtke <helmwo@gmail.com> - 2012-03-27 05:26 -0700
                Re: Which standard? "Peter Knaggs" <pjk@bcs.org.uk> - 2012-03-29 00:10 +0100
                Re: Which standard? Hugh Aguilar <hughaguilar96@yahoo.com> - 2012-03-29 00:51 -0700
                Re: Which standard? Marc Olschok <nobody@nowhere.invalid> - 2012-03-30 16:13 +0000
                Re: Which standard? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-03-30 13:01 -0500
                Re: Which standard? "Elizabeth D. Rather" <erather@forth.com> - 2012-03-30 09:18 -1000
                Re: Which standard? Alex McDonald <blog@rivadpm.com> - 2012-03-30 14:11 -0700
                Re: Which standard? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-03-31 08:18 -0500
                Re: Which standard? Marc Olschok <nobody@nowhere.invalid> - 2012-04-10 12:43 +0000
                Re: Which standard? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-04-10 10:15 -0500
                Re: Which standard? "Elizabeth D. Rather" <erather@forth.com> - 2012-04-10 08:22 -1000
                Re: Which standard? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-04-10 14:03 -0500
                Re: Which standard? Alex McDonald <blog@rivadpm.com> - 2012-04-10 12:17 -0700
                Re: Which standard? "Elizabeth D. Rather" <erather@forth.com> - 2012-04-10 09:26 -1000
                Re: Which standard? Alex McDonald <blog@rivadpm.com> - 2012-04-11 06:22 -0700
                Re: Which standard? Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-04-11 12:42 +0000
                Re: Which standard? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-04-11 09:40 -0500
                Re: Which standard? BruceMcF <agila61@netscape.net> - 2012-04-11 07:55 -0700
                Re: Which standard? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-04-11 11:28 -0500
                Re: Which standard? BruceMcF <agila61@netscape.net> - 2012-04-10 12:38 -0700
                Re: Which standard? Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-04-03 09:27 +0000
                Re: Which standard? Marc Olschok <nobody@nowhere.invalid> - 2012-04-10 12:44 +0000
                Re: Which standard? "Rod Pemberton" <do_not_have@noavailemail.cmm> - 2012-03-25 05:47 -0400
                Re: Which standard? BruceMcF <agila61@netscape.net> - 2012-03-25 07:49 -0700
              Re: Which standard? BruceMcF <agila61@netscape.net> - 2012-03-24 15:07 -0700
          Re: Which standard? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-03-24 05:44 -0500
      Re: Which standard? Hans Bezemer <the.beez.speaks@gmail.com> - 2012-03-23 19:54 +0100
        Re: Which standard? "Rod Pemberton" <do_not_have@noavailemail.cmm> - 2012-03-23 21:52 -0400
          Re: Which standard? Hans Bezemer <the.beez.speaks@gmail.com> - 2012-03-24 12:13 +0100
            Re: Which standard? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-03-24 06:24 -0500
              Re: Which standard? Hans Bezemer <the.beez.speaks@gmail.com> - 2012-03-24 13:37 +0100
                Re: Which standard? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-03-24 12:20 -0500
                Re: Which standard? "Rod Pemberton" <do_not_have@noavailemail.cmm> - 2012-03-24 17:24 -0400
        Re: Which standard? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-03-24 14:18 +0000
      Re: Which standard? Hans Bezemer <the.beez.speaks@gmail.com> - 2012-03-23 22:33 +0100
      Re: Which standard? Bernd Paysan <bernd.paysan@gmx.de> - 2012-03-26 03:25 +0200
      Re: Which standard? BruceMcF <agila61@netscape.net> - 2012-03-25 21:40 -0700
    Re: Which standard? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-03-22 04:15 -0500
    Re: Which standard? Fritz Wuehler <fritz@spamexpire-201203.rodent.frell.theremailer.net> - 2012-03-22 13:02 +0100
  Re: Which standard? Helmar Wodtke <helmwo@gmail.com> - 2012-03-25 08:51 -0700
  Re: Which standard? jacko <jackokring@gmail.com> - 2012-03-26 22:14 -0700
    Re: Which standard? Hugh Aguilar <hughaguilar96@yahoo.com> - 2012-03-26 23:55 -0700
      Re: Which standard? Helmar Wodtke <helmwo@gmail.com> - 2012-03-27 05:41 -0700
        Re: Which standard? hwfwguy@gmail.com - 2012-03-27 08:45 -0700
        Re: Which standard? Bernd Paysan <bernd.paysan@gmx.de> - 2012-03-28 01:42 +0200
          Re: Which standard? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-03-31 13:46 +0000
        Re: Which standard? Hugh Aguilar <hughaguilar96@yahoo.com> - 2012-03-27 22:51 -0700
        Re: Which standard? jacko <jackokring@gmail.com> - 2012-03-27 19:33 -0700

csiph-web