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.commailto:schuster.wolfgang@gmail.com> wrote:
Am 18.04.2013 um 14:55 schrieb "Meer, H. van der" <H.vanderMeer@uva.nlmailto: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