Which input to use?

From	Lauri Alanko <la@iki.fi>
Newsgroups	comp.lang.forth
Subject	Which input to use?
Date	2014-04-06 14:13 +0000
Organization	University of Helsinki
Message-ID	<lhrndd$2pa$1@speranza.aioe.org> (permalink)

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Hello.

I'm a bit confused by the design of Forth's input system. If I read
the Forth 2012 draft correctly, we have the following:

* The user input device. This is just some system-dependent input
source that is read with KEY and ACCEPT.

* Files. These are read with READ-FILE and READ-LINE.

* The input source. This is used by parsing words during
interpretation. The input source is accessed through the input buffer
with SOURCE, >IN and REFILL.

This all seems terribly complicated from the programmer's point of
view. What if I just want to write general-purpose text processing
code that can be used with arbitrary inputs? Now it seems I have to
write a separate abstraction layer to deal with the above cases.

I would have expected there to be either a way to make a file into the
user input device, or to treat the user input device as a file, so one
could use a single interface uniformly.

Funnily enough, there is one abstraction layer already in place: the
input source, which can be set to read either from the user input
device (with QUIT) or from a file (with INCLUDE-FILE). It even has a
number of useful parsing primitives available already.

But unfortunately it seems that there is no way to change the input
source without starting to interpret it immediately. So it seems that
the input source cannot be used as an input abstraction layer if we
are reading data that isn't structured as Forth words.

Have I understood the situation correctly? Is there some reason for
these limitations?


Lauri

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Thread

Which input to use? Lauri Alanko <la@iki.fi> - 2014-04-06 14:13 +0000
  Re: Which input to use? mhx@iae.nl - 2014-04-06 07:59 -0700
    Re: Which input to use? "Elizabeth D. Rather" <erather@forth.com> - 2014-04-06 08:26 -1000
      Re: Which input to use? hughaguilar96@yahoo.com - 2014-04-19 19:48 -0700
        Re: Which input to use? "Alex McDonald" <blog@rivadpm.com> - 2014-04-21 02:09 +0100
          Re: Which input to use? "Rod Pemberton" <dont_use_email@xnothavet.cqm> - 2014-04-21 04:01 -0400
  Re: Which input to use? hughaguilar96@yahoo.com - 2014-04-06 23:16 -0700
  Re: Which input to use? albert@spenarnc.xs4all.nl (Albert van der Horst) - 2014-04-07 10:44 +0000
  Re: Which input to use? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2014-04-07 17:45 +0000
    Re: Which input to use? mhx@iae.nl - 2014-04-07 12:09 -0700
      Re: Which input to use? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2014-04-08 16:11 +0000
        Re: Which input to use? mhx@iae.nl - 2014-04-08 13:05 -0700
    Re: Which input to use? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2014-04-08 03:18 -0500
      Re: Which input to use? albert@spenarnc.xs4all.nl (Albert van der Horst) - 2014-04-08 10:49 +0000
        Re: Which input to use? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2014-04-09 16:07 +0000
          Re: Which input to use? albert@spenarnc.xs4all.nl (Albert van der Horst) - 2014-04-10 01:36 +0000
            Re: Which input to use? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2014-04-11 17:59 +0000
      Re: Which input to use? "Alex McDonald" <blog@rivadpm.com> - 2014-04-08 12:28 +0100
      Re: Which input to use? hughaguilar96@yahoo.com - 2014-04-08 21:03 -0700
        Re: Which input to use? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2014-04-09 03:14 -0500
      EXECUTE-PARSING (was: Which input to use?) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2014-04-09 15:13 +0000
        Re: EXECUTE-PARSING (was: Which input to use?) Bernd Paysan <bernd.paysan@gmx.de> - 2014-04-09 18:54 +0200
          Re: EXECUTE-PARSING (was: Which input to use?) Alexander Skobelev <al.skobelev@gmail.com> - 2014-04-09 22:44 -0700

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