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Re: Recognizers and LOCATE

From anton@mips.complang.tuwien.ac.at (Anton Ertl)
Newsgroups comp.lang.forth
Subject Re: Recognizers and LOCATE
Date 2017-01-29 16:18 +0000
Organization Institut fuer Computersprachen, Technische Universitaet Wien
Message-ID <2017Jan29.171814@mips.complang.tuwien.ac.at> (permalink)
References (4 earlier) <udGdnbkweYIOrBfFnZ2dnUU7-f_NnZ2d@supernews.com> <2017Jan27.101029@mips.complang.tuwien.ac.at> <Pr2dnV0-9prY8xbFnZ2dnUU7-TvNnZ2d@supernews.com> <2017Jan27.171653@mips.complang.tuwien.ac.at> <x9idnVvJkslr7hHFnZ2dnUU7-bvNnZ2d@supernews.com>

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Andrew Haley <andrew29@littlepinkcloud.invalid> writes:
>Anton Ertl <anton@mips.complang.tuwien.ac.at> wrote:
>> Andrew Haley <andrew29@littlepinkcloud.invalid> writes:
>>>Of course I can, but that's not the point.  For example, if ALLOCATE
>>>were used to hold a scanned string later to be consumed (and FREEd) by
>>>one of the methods, a recognizer would leak memory when used by
>>>LOCATE.
>> 
>> If that is the kind of problem you have in mind, I will accept it
>> gladly
>
>I'm sure you would, but it's a bug

Not necessarily.

>> However, there are other things that one would not want, such as
>> changing BASE in the recognizer and changing it back in the methods; I
>> don't think that anybody would want to do that, but if you think it is
>> helpful, suggest language that would discourage such usage.
>
>Exactly.  We need to say something.  I'm not yet sure what, exactly,
>but I think something like idempotency is the property needed.

I think it's enough to say that, even in the case of recognizer
success, the methods may not be invoked at all, or there may be
arbitrary code performed between the recognizer and the methods, and
that the recognizer and methods should be designed to be correct even
under those circumstances.

>> Go ahead, produce test cases that show breakage in the current
>> recognizer proposal.
>
>I've already shown a memory leak.  That is a bug, even if you don't
>think it's an interesting one.

No, I don't consider it a bug.

>You've mentioned toggling BASE in a
>recognizer, too.  Those will do for the time being.

I don't see any test cases, just some prose.

>> Yes.  Now the recognizer proposal is not my creation; and the Gforth
>> implementation is not my creation, either.
>
>I'm not sure that makes any difference, really.

It certainly makes a difference to your argument, which was "that
people are so in love with their creations" (interestingly, while you
are usually not very eager in trimming quoted material, you trimmed
that one).  In fact, I explored an alternative approach (temporary
words) in my EuroForth 2016 paper on recognizers; while the temprary
word approach is conceptually simple and cute, the RfD approach is
more practical in a standardization setting.  But anyway, this should
demonstrate that I am pretty open to changing the interface; I am
opposed to complicating it without significant gain, however.

>> While I am very fussy about the specifics of words used in portable
>> programs such as COMPILE, and S", I don't think we need to be as
>> fussy with respect to programming tools like WORDS, SEE, and LOCATE.
>> That's because nobody uses these words in portable programs; they
>> are just used by programmers during development, and they do what
>> they do, and programmers adapt their usage to the behaviour of the
>> word.
>
>That's an interesting view.  So you know it's a bug, but you don't
>think it's significant.

A parsing WORDS in a system that claims to conform to Forth-94 without
specifying an appropriate environmental restriction is certainly a
bug.

- 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 2016: http://www.euroforth.org/ef16/

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Recognizers and LOCATE Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-01-24 12:38 -0600
  Recognizers and LOCATE JennyB <jennybrien@googlemail.com> - 2017-01-24 10:56 -0800
    Re: Recognizers and LOCATE Bernd Paysan <bernd@net2o.de> - 2017-01-24 22:25 +0000
      Re: Recognizers and LOCATE Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-01-25 03:16 -0600
        Re: Recognizers and LOCATE JennyB <jennybrien@googlemail.com> - 2017-01-25 08:37 -0800
          Re: Recognizers and LOCATE Alex <alex@rivadpm.com> - 2017-01-25 14:22 -0500
            Re: Recognizers and LOCATE Alex <alex@rivadpm.com> - 2017-01-25 14:26 -0500
            Re: Recognizers and LOCATE Matthias Trute <matthias.trute@gmail.com> - 2017-01-25 11:49 -0800
              Re: Recognizers and LOCATE Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-01-26 03:33 -0600
                Re: Recognizers and LOCATE Matthias Trute <matthias.trute@gmail.com> - 2017-01-26 10:14 -0800
                Re: Recognizers and LOCATE JennyB <jennybrien@googlemail.com> - 2017-01-26 11:04 -0800
            Re: Recognizers and LOCATE Bernd Paysan <bernd@net2o.de> - 2017-01-26 01:24 +0000
              Re: Recognizers and LOCATE Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-01-26 06:26 -0600
                Re: Recognizers and LOCATE Bernd Paysan <bernd@net2o.de> - 2017-03-12 00:47 +0000
                Re: Recognizers and LOCATE albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2017-03-12 17:01 +0100
                Re: Recognizers and LOCATE Matthias Trute <matthias.trute@gmail.com> - 2017-03-13 12:31 -0700
                Re: Recognizers and LOCATE Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-03-14 04:51 -0500
                Re: Recognizers and LOCATE Matthias Trute <matthias.trute@gmail.com> - 2017-03-14 12:48 -0700
              Re: Recognizers and LOCATE Alex <alex@rivadpm.com> - 2017-01-27 17:18 +0000
                Re: Recognizers and LOCATE Matthias Trute <matthias.trute@gmail.com> - 2017-01-27 09:28 -0800
                Re: Recognizers and LOCATE Alex <alex@rivadpm.com> - 2017-01-27 17:35 +0000
                Re: Recognizers and LOCATE Matthias Trute <matthias.trute@gmail.com> - 2017-01-28 04:29 -0800
        Re: Recognizers and LOCATE Bernd Paysan <bernd@net2o.de> - 2017-01-25 21:07 +0000
          Re: Recognizers and LOCATE anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-01-26 11:24 +0000
            Re: Recognizers and LOCATE Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-01-26 06:23 -0600
              Re: Recognizers and LOCATE anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-01-26 15:39 +0000
                Re: Recognizers and LOCATE Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-01-26 11:14 -0600
                Re: Recognizers and LOCATE anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-01-27 08:37 +0000
                Re: Recognizers and LOCATE Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-01-27 03:26 -0600
                Re: Recognizers and LOCATE anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-01-27 11:37 +0000
                Re: Recognizers and LOCATE stephen@mpeforth.com (Stephen Pelc) - 2017-01-27 17:28 +0000
                Re: Recognizers and LOCATE Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-01-28 04:22 -0600
                Re: Recognizers and LOCATE Matthias Trute <matthias.trute@gmail.com> - 2017-01-28 04:35 -0800
                Re: Recognizers and LOCATE JennyB <jennybrien@googlemail.com> - 2017-01-28 07:03 -0800
                Re: Recognizers and LOCATE Matthias Trute <matthias.trute@gmail.com> - 2017-01-28 07:42 -0800
                Re: Recognizers and LOCATE anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-01-28 17:25 +0000
                Re: Recognizers and LOCATE peter.m.falth@gmail.com - 2017-01-28 08:05 -0800
                Re: Recognizers and LOCATE JennyB <jennybrien@googlemail.com> - 2017-01-28 09:27 -0800
                Re: Recognizers and LOCATE albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2017-01-28 19:18 +0100
                Re: Recognizers and LOCATE Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-01-29 04:35 -0600
                Re: Recognizers and LOCATE anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-01-29 16:59 +0000
                Re: Recognizers and LOCATE albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2017-01-29 19:40 +0100
                Re: Recognizers and LOCATE anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-01-31 17:01 +0000
                Re: Recognizers and LOCATE Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-01-31 04:12 -0600
                Re: Recognizers and LOCATE Bernd Paysan <bernd@net2o.de> - 2017-03-12 01:25 +0000
                Re: Recognizers and LOCATE minforth@arcor.de - 2017-03-12 01:30 -0800
                Re: Recognizers and LOCATE anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-03-12 10:07 +0000
                Re: Recognizers and LOCATE Bernd Paysan <bernd@net2o.de> - 2017-03-15 23:30 +0000
                Re: Recognizers and LOCATE anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-03-16 11:59 +0000
                Re: Recognizers and LOCATE Bernd Paysan <bernd@net2o.de> - 2017-03-17 21:46 +0000
                Re: Recognizers and LOCATE Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-03-12 06:51 -0500
                Re: Recognizers and LOCATE anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-03-12 13:05 +0000
                Re: Recognizers and LOCATE Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-03-12 12:04 -0500
  Re: Recognizers and LOCATE albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2017-01-24 20:41 +0100
  Re: Recognizers and LOCATE anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-01-26 11:52 +0000
    Re: Recognizers and LOCATE Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-01-26 08:20 -0600
      Re: Recognizers and LOCATE anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-01-26 16:26 +0000
        Re: Recognizers and LOCATE Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-01-26 11:27 -0600
          Re: Recognizers and LOCATE anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-01-27 09:10 +0000
            Re: Recognizers and LOCATE Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-01-27 09:59 -0600
              Re: Recognizers and LOCATE anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-01-27 16:16 +0000
                Re: Recognizers and LOCATE Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-01-28 04:35 -0600
                Re: Recognizers and LOCATE albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2017-01-28 19:41 +0100
                Re: Recognizers and LOCATE anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-01-29 16:18 +0000
                Re: Recognizers and LOCATE Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-01-31 04:21 -0600
                Re: Recognizers and LOCATE Bernd Paysan <bernd@net2o.de> - 2017-03-12 01:07 +0000
    Re: Recognizers and LOCATE albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2017-01-26 21:08 +0100
      Re: Recognizers and LOCATE anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-01-27 10:13 +0000

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