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Re: ?EXEC

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Albert van der Horst <albert@spenarnc.xs4all.nl> writes:
>In article <2012Jun17.142751@mips.complang.tuwien.ac.at>,
>Anton Ertl <anton@mips.complang.tuwien.ac.at> wrote:
>>Albert van der Horst <albert@spenarnc.xs4all.nl> writes:
>>>I just discovered that having ?COMP in IF and DO is useful.
>>
>>No, it's the plague.  It turns nicely working words into STATE-smart
>>crap.  ?COMP (like all STATE-smart words) tests STATE at run-time,
>>whereas what is wanted is to have a check at parsing time (and that's
>>the same for all STATE-smart words).
>
>In this case the problem happens at parsing time, so the check is
>done at the right time, i.e. while interpreting. Think about it.
>?EXEC can never be a proper error message. ?COMP can never hinder
>postponing something. Has nothing to do with state smartness.

Try <http://www.complang.tuwien.ac.at/forth/postponetest.fs> and see
how IF and DO with ?COMP are broken.

>When was the last time you did
>: aaap .... [ IF ] .... ;
>while you could have done
>: aaap ....  IF  .... ;

In a compiler where the text interpreter checks for compile-only words
(like Gforth) the first version would fail because IF is compile-only
and thus can only be compiled.

However, the issue is not 

: aaap ... [ IF ] ... ;

but

: baz ... [ 3 5 gen-foo s" bla" gen-bar ] ... ;

where GEN-FOO contains, e.g., a "POSTPONE IF".

Yes, the ?COMP does not hinder POSTPONEing the IF, it just fails when
GEN-FOO runs.  And it has everything to do with STATE-smartness: It
checks STATE at run-time, like any other STATE-smart word.

And yes, I have written production code where a code generator is
invoked in interpret state.

>>If you want to protect against using IF and DO interpretively, add a
>>compile-only flag to the header, and let the text interpreter check
>>it.  For more complicated cases (words that can be used
>>interpretively, but behave differently), there are a number of good
>>implementation approaches (checking STATE at run-time is not one of
>>them).
...
>Making the text interpreter smarter is the opposite way from where
>I want to go.

If you don't want to go there, then don't.  Just live without
recognizing interpretive uses of IF and DO.  But if you want to
recognize them, do it properly.  STATE-smartness (including ?COMP) is
both broken and more complicated than not checking at all, i.e., it's
a lose-lose solution.

- 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 2012: http://www.euroforth.org/ef12/

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?EXEC Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-06-15 20:40 +0000
  Re: ?EXEC "Ed" <invalid@nospam.com> - 2012-06-16 11:14 +1000
  Re: ?EXEC BruceMcF <agila61@netscape.net> - 2012-06-16 07:10 -0700
    Re: ?EXEC Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-06-17 03:01 +0000
      Re: ?EXEC "Ed" <invalid@nospam.com> - 2012-06-17 13:36 +1000
      Re: ?EXEC anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-06-17 12:27 +0000
        Re: ?EXEC Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-06-17 20:45 +0000
          Re: ?EXEC anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-06-18 13:31 +0000
            Re: ?EXEC Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-06-18 18:29 +0000
              Re: ?EXEC "Elizabeth D. Rather" <erather@forth.com> - 2012-06-18 08:01 -1000
              Re: ?EXEC anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-06-19 14:09 +0000
                Re: ?EXEC Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-06-19 10:51 -0500
                Re: ?EXEC anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-06-19 16:04 +0000
                Re: ?EXEC Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-06-19 12:45 -0500
                Re: ?EXEC anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-06-20 10:50 +0000
                Re: ?EXEC Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-06-20 07:10 -0500
                Re: ?EXEC anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-06-20 12:47 +0000
                Re: ?EXEC Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-06-19 22:52 +0000
                Re: ?EXEC anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-06-20 10:59 +0000
                Defining Compilation Behaviour - was Re: ?EXEC JennyB <jennybrien@googlemail.com> - 2012-06-21 04:58 -0700
                Re: Defining Compilation Behaviour - was Re: ?EXEC anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-06-21 15:44 +0000
            Re: ?EXEC Bernd Paysan <bernd.paysan@gmx.de> - 2012-06-19 02:11 +0200
              Re: ?EXEC "Elizabeth D. Rather" <erather@forth.com> - 2012-06-18 14:45 -1000
                Re: ?EXEC Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-06-19 10:48 +0000
                Re: ?EXEC anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-06-19 15:53 +0000
                Re: ?EXEC Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-06-19 23:00 +0000
                Re: ?EXEC anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-06-20 11:09 +0000
                Re: ?EXEC BruceMcF <agila61@netscape.net> - 2012-06-20 07:39 -0700
                Re: ?EXEC anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-06-20 15:32 +0000
                Re: ?EXEC BruceMcF <agila61@netscape.net> - 2012-06-21 11:24 -0700
                Re: ?EXEC Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-06-20 22:43 +0000
                Re: ?EXEC Bernd Paysan <bernd.paysan@gmx.de> - 2012-06-21 21:39 +0200
                Re: ?EXEC Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-06-22 02:33 -0500
                Re: ?EXEC anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-06-22 11:12 +0000
                Re: ?EXEC Bernd Paysan <bernd.paysan@gmx.de> - 2012-06-22 21:34 +0200
                Re: ?EXEC anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-06-24 14:58 +0000
                Re: ?EXEC Bernd Paysan <bernd.paysan@gmx.de> - 2012-06-24 23:53 +0200
                Re: ?EXEC anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-06-19 15:43 +0000
              Re: ?EXEC anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-06-19 14:52 +0000
                Re: ?EXEC Bernd Paysan <bernd.paysan@gmx.de> - 2012-06-21 22:15 +0200
                Re: ?EXEC stephenXXX@mpeforth.com (Stephen Pelc) - 2012-06-22 10:32 +0000
                Re: ?EXEC Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-06-22 05:49 -0500
                Alternatives to S" and TO (was: ?EXEC) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-06-22 15:19 +0000
                Re: Alternatives to S'' and TO mhx@iae.nl (Marcel Hendrix) - 2012-06-22 20:37 +0200
                Re: Alternatives to S'' and TO anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-06-23 14:46 +0000
                Re: Alternatives to S" and TO (was: ?EXEC) BruceMcF <agila61@netscape.net> - 2012-06-22 12:32 -0700
                Re: Alternatives to S" and TO Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-06-23 03:07 -0500
                Re: Alternatives to S" and TO anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-06-23 13:32 +0000
                Re: Alternatives to S" and TO Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-06-24 08:50 -0500
                Re: Alternatives to S" and TO anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-06-24 15:39 +0000
                Re: Alternatives to S" and TO Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-06-25 04:49 -0500
                Re: Alternatives to S" and TO BruceMcF <agila61@netscape.net> - 2012-06-25 07:17 -0700
                Re: Alternatives to S" and TO Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-06-25 10:13 -0500
                Re: Alternatives to S" and TO (was: ?EXEC) Alex McDonald <blog@rivadpm.com> - 2012-06-23 16:01 -0700
                Re: Alternatives to S" and TO (was: ?EXEC) Bernd Paysan <bernd.paysan@gmx.de> - 2012-06-24 01:59 +0200
                Re: Alternatives to S" and TO (was: ?EXEC) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-06-24 13:21 +0000
                Re: Alternatives to S" and TO (was: ?EXEC) Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-06-24 16:50 +0000
                Re: Alternatives to S" and TO (was: ?EXEC) Bernd Paysan <bernd.paysan@gmx.de> - 2012-06-27 23:30 +0200
                Re: Alternatives to S" and TO (was: ?EXEC) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-06-24 13:15 +0000
                Re: Alternatives to S" and TO (was: ?EXEC) Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-06-24 16:47 +0000
                Re: ?EXEC Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-06-22 20:34 +0000
                Re: ?EXEC Bernd Paysan <bernd.paysan@gmx.de> - 2012-06-22 21:46 +0200
                Re: ?EXEC "Elizabeth D. Rather" <erather@forth.com> - 2012-06-22 10:16 -1000
                Re: ?EXEC Bernd Paysan <bernd.paysan@gmx.de> - 2012-06-22 22:43 +0200
                Re: ?EXEC "Elizabeth D. Rather" <erather@forth.com> - 2012-06-22 11:18 -1000
                Re: ?EXEC anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-06-23 13:50 +0000
      Re: ?EXEC BruceMcF <agila61@netscape.net> - 2012-06-17 10:41 -0700
  Re: ?EXEC anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-06-17 12:52 +0000
    Re: ?EXEC "Elizabeth D. Rather" <erather@forth.com> - 2012-06-17 08:03 -1000
      Re: ?EXEC "Ed" <invalid@nospam.com> - 2012-06-18 15:06 +1000
        Re: ?EXEC "Elizabeth D. Rather" <erather@forth.com> - 2012-06-17 20:31 -1000
          Re: ?EXEC "Ed" <invalid@nospam.com> - 2012-06-21 13:07 +1000
            Re: ?EXEC Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-06-21 14:00 +0000
              Re: ?EXEC BruceMcF <agila61@netscape.net> - 2012-06-21 07:51 -0700
              Re: ?EXEC anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-06-21 15:39 +0000
                Re: ?EXEC Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-06-21 20:28 +0000
                Re: ?EXEC "Ed" <invalid@nospam.com> - 2012-06-28 14:22 +1000
                Re: ?EXEC Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-06-28 04:00 -0500
            Re: ?EXEC anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-06-21 16:09 +0000
            Re: ?EXEC Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-06-21 11:51 -0500
              Re: ?EXEC BruceMcF <agila61@netscape.net> - 2012-06-21 11:21 -0700
                Re: ?EXEC Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-06-22 01:42 -0500
                Re: ?EXEC "Elizabeth D. Rather" <erather@forth.com> - 2012-06-21 21:47 -1000
                Re: ?EXEC anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-06-22 15:10 +0000
                Re: ?EXEC Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-06-22 20:39 +0000
                Re: ?EXEC BruceMcF <agila61@netscape.net> - 2012-06-22 12:47 -0700
                Re: ?EXEC BruceMcF <agila61@netscape.net> - 2012-06-22 12:53 -0700
        Re: ?EXEC stephenXXX@mpeforth.com (Stephen Pelc) - 2012-06-21 08:39 +0000
          Re: ?EXEC "Ed" <invalid@nospam.com> - 2012-06-23 15:36 +1000
            Re: ?EXEC stephenXXX@mpeforth.com (Stephen Pelc) - 2012-06-23 10:58 +0000
              Re: ?EXEC "Ed" <invalid@nospam.com> - 2012-06-25 14:26 +1000
                Re: ?EXEC stephenXXX@mpeforth.com (Stephen Pelc) - 2012-06-25 08:37 +0000
      Re: ?EXEC Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-06-18 10:34 +0000
  Re: ?EXEC Coos Haak <chforth@hccnet.nl> - 2012-06-18 17:47 +0200
    Re: ?EXEC Coos Haak <chforth@hccnet.nl> - 2012-06-18 17:49 +0200
  Re: ?EXEC jacko <jackokring@gmail.com> - 2012-06-22 15:43 -0700

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