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Re: The joy of formatting

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On 4/05/2026 12:11 am, Anton Ertl wrote:
> dxf <dxforth@gmail.com> writes:
>> IIRC the standard makes no mention of what needs preserving.
> 
> It actually states explicitly what is not guaranteed to be preserved.
> In particular,
> <https://forth-standard.org/standard/usage#subsubsection.3.3.3.6>
> says:
> 
> |The previous contents of the regions identified by [...] #> may be
> |invalid after each use of these words. Further, the regions returned
> |by [...] #> may overlap in memory. Consequently, use of one of these
> |words can corrupt a region returned earlier by a different word. The
> |other words that construct pictured numeric output strings (<#, #, #S,
> |HOLD, HOLDS, XHOLD) may also modify the contents of these
> |regions. Words that display numbers may be implemented using pictured
> |numeric output words. Consequently, . (dot), .R, .S, ?, D., D.R, U.,
> |U.R could also corrupt the regions.
> 
> Note that AT-XY is not included in this list (and chapter 10 does not
> add it to this list).  So
> 
> 123. <# #s #> 3 4 at-xy type
> 
> should display "123" at position 3,4.  Testing this with a few Forth
> systems, gforth, iforth, and SwiftForth pass this test, while lxf and
> VFX don't.

AFAICS there's nothing in the standard that says it "should" display
123 in that case.  What happens in the absence of specification becomes
a matter of interpretation.  We know the standard made effort to specify
corner cases e.g. u=0 in CMOVE.  So if it were up to me I would say the
standard simply didn't consider the case you specify.  One certainly
needs to ask what is the likelihood of the case you specify arising.

> 
>> Some
>> implementations preserve BASE; while others don't.
>> As far as standard words are concerned, only DECIMAL and HEX are
> allowed to change BASE (the specification of DECIMAL could be better,
> however), and of courseyou can change BASE explicitly, e.g., with
> 
> BASE !

Unlike the HOLD buffer, I would say a case can be made for preserving
BASE across AT-XY calls.  Since ANSI AT-XY sends coords in ASCII decimal
rather than binary, it would be a burden on apps to ensure BASE was
decimal.  In such case I would seriously have to consider Albert's
DEC: - irrespective of whether my AT-XY was personally affected or not.
From a brief survey I would say most ANSI AT-XY implementations do in
fact preserve BASE.  And perhaps the standard should specify that.

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The joy of formatting albert@spenarnc.xs4all.nl - 2026-04-29 15:41 +0200
  Re: The joy of formatting dxf <dxforth@gmail.com> - 2026-04-30 12:11 +1000
    Re: The joy of formatting Hans Bezemer <the.beez.speaks@gmail.com> - 2026-04-30 09:48 +0200
    Re: The joy of formatting albert@spenarnc.xs4all.nl - 2026-04-30 11:06 +0200
      Re: The joy of formatting Hans Bezemer <the.beez.speaks@gmail.com> - 2026-04-30 23:34 +0200
    Re: The joy of formatting albert@spenarnc.xs4all.nl - 2026-04-30 11:11 +0200
      Re: The joy of formatting dxf <dxforth@gmail.com> - 2026-04-30 23:58 +1000
        Re: The joy of formatting albert@spenarnc.xs4all.nl - 2026-04-30 18:11 +0200
          Re: The joy of formatting dxf <dxforth@gmail.com> - 2026-05-01 09:57 +1000
            Re: The joy of formatting anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-05-01 06:03 +0000
              Re: The joy of formatting dxf <dxforth@gmail.com> - 2026-05-03 23:09 +1000
                Re: The joy of formatting anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-05-03 14:11 +0000
                Re: The joy of formatting dxf <dxforth@gmail.com> - 2026-05-04 11:02 +1000
      Re: The joy of formatting minforth <minforth@gmx.net> - 2026-04-30 20:47 +0200
        Re: The joy of formatting Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-05-03 09:07 -0500

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