Re: Recognizers and LOCATE

From	anton@mips.complang.tuwien.ac.at (Anton Ertl)
Newsgroups	comp.lang.forth
Subject	Re: Recognizers and LOCATE
Date	2017-01-26 16:26 +0000
Organization	Institut fuer Computersprachen, Technische Universitaet Wien
Message-ID	<2017Jan26.172625@mips.complang.tuwien.ac.at> (permalink)
References	<Hd2dnfK32o-9AhrFnZ2dnUU7-bHNnZ2d@supernews.com> <2017Jan26.125252@mips.complang.tuwien.ac.at> <urWdnUJubp0_mBfFnZ2dnUU7-dXNnZ2d@supernews.com>

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Andrew Haley <andrew29@littlepinkcloud.invalid> writes:
>Anton Ertl <anton@mips.complang.tuwien.ac.at> wrote:
>> : f1+ 1e f+ ;  ok
>> locate 1e 1e Can't be located
>>
>> Panic!  The system must be broken!
>
>Oh, no.  I should have predicted that response.  :-(
>
>Obviously the maintenace programmer is a Forth programmer, and knows
>what a number is.

I expect that maintainence programmers will also be familiar with the
recognizers used in the programs they maintain.  E.g., if they come
across "Myline.end.y", they will know that there is a word MYLINE, a
word END, and a word Y, and they can try to LOCATE that (hmm, setting
up the search order to have END and Y visible might be cumbersome;
does ClassVFX have a way to deal with that?)

But having a tool for finding out which recognizer recognizes a word
can indeed be useful (and has been useful) when dealing with wide and
overlapping recognizers (not a practice I recommend, but Bernd Paysan
likes that), especially when a recognizer is too wide and recognizes
something that should be an error.

>>>and indeed might have other effects, change >IN, and so on.
>>
>> If you want to restore >IN, you can do that, but I think it's better
>> not to restore it:
>
>That's not what I meant.  A recognizer might andvance >IN beyond the
>initial parsed word, and indeed the RFC mentions this possibility.

Yes, and I gave an example (the only one known) where that comes into
play.  Here it is again, for more diligent consideration:

|"abc def" type abc def ok
|locate "abc def" 
|quotedstring.fs:24:3
|...
|*   24: : rec:string ( addr u -- addr u' r:string | r:fail )
|...

Now what would happen if >IN would be restored to point right before
'def"'?

>Other side effetcs are possible.

Such as?

>>>For this reason they can't be called by LOCATE: LOCATE must be
>>>side-effect free.
>>
>> Where does it say so?
>
> LOCATE <name> ( -- )  Common usage
>
> If name is the name of a definition compiled from source code,
> display the source code for name. On some systems, the phrase VIEW
> name performs a similar function.

That's not an answer to my question.  But anyway, someone documented
his LOCATE to work for names of definitions compiled from source code,
so a LOCATE that worked for recognized strings would not fit this
description anyway; no need to worry about the recognizer changing
>IN, then.

>> I have seen this tactic before.
>
>It's not intended to be a disruptive tactic.  I'm engaging with the
>proposal in a positive way, by pointing out how it might be improved.

Maybe you are.  That does not mean that the end result is not the
same.

I remember stories from other areas (e.g., LWN covers such stories now
and then) where gatekeepers gave a developer one hoop after another to
jump through, and the end result pleased no one; I don't know in how
many such cases the developer gave up at one point (that probably
happens silently and does not get a story on LWN), but in the typical
story as reported someone eventually decided that all the hoop-jumping
had not improved the work, and accepted a simpler non-hoop-compliant
version.  In a recent story, <https://lwn.net/Articles/711013/>, the
developer had jumped through all the officially required hoops in
advance, and wrote a huge patch to cover all the bases, and what was
eventually accepted was a kind of mininal solution that does not jump
any hoops.

- 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/

Thread

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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