Re: halign broken

From: "Meer, H. van der" <H.vanderMeer@uva.nl>
To: mailing list for ConTeXt users <ntg-context@ntg.nl>
Subject: Re: halign broken
Date: Thu, 18 Apr 2013 13:16:20 +0000	[thread overview]
Message-ID: <09B17E1D-F5C1-4C93-BB82-FF515EA1D51F@uva.nl> (raw)
In-Reply-To: <ADCB0AEB-8AF3-4E73-A49D-4DC8FEB4AF3E@gmail.com>

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I see, it is either the nuisance of having to type \& etc. in the text, or the nuisance of having to wrap everything like \halign in \unprotect..\protect and then resorting to \& again.
At least there is nothing amiss with \halign itself, which is reassuring. However, I do not feel secure with these little deviations from the orginal TeX.

Hans van der Meer

On 18 Apr 2013, at 3:03 PM, Wolfgang Schuster <schuster.wolfgang@gmail.com<mailto:schuster.wolfgang@gmail.com>>
 wrote:

Am 18.04.2013 um 14:55 schrieb "Meer, H. van der" <H.vanderMeer@uva.nl<mailto:H.vanderMeer@uva.nl>>:

There seems something very much amiss with \halign in later ConTeXt versions.

This typesets fine in PlainTeX and is an example taken from a textbook.

  \tabskip=1em\halign{%
  \hfil\it#\hfil&\hfil#\hfil&#&\hfil#\crA&B&C&D\cr}

Also in contextversion 2012.05.30 (from a TeXlive distribution).

But it fails at least in ConTeXt  ver: 2013.03.20 10:34 MKIV
and in ConTeXt  ver: 2013.04.16 12:08 MKIV beta
with the following error

! Only one # is allowed per tab.
system          > tex > error on line 5 in file fixedwidth.tex: Only one # is allowed per tab ...

 1     \starttext
 2     contextversion=\contextversion\par
 3     \tabskip=1em
 4     \halign{%
 5 >>  \hfil\it#\hfil&\hfil#\hfil&#&\hfil#\cr
 6     A&B&C&D\cr}
 7     \stoptext
l.5 \hfil\it#\hfil&\hfil#
                       \hfil&#&\hfil#\cr

Why? How primitive it may be, I would like to use \halign now and then.

The error message is misleading because the problem is & and not #.

One of the changes for MkIV was to make _, ^ and & normal characters
in the document (the first two still works for math). For code writing this
doesn’t matter because & has it’s normal meaning when you use
\unprotect … \protect but it can’t be used in the document.

Wolfgang

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