At 2025-10-28T04:18:33-0400, Thomas Dickey wrote: > On Mon, Oct 27, 2025 at 07:58:42PM -0500, G. Branden Robinson wrote: [rearranging] > > AC_DEFUN([TBL_SUPPORTS_X_COLUMN_MODIFIER], [ [snip] > thanks - I can adapt this (use it as a starting point)
Sounds good to me. Regarding the sed part of the remedy...
> > At 2025-10-27T04:15:57-0400, Thomas Dickey wrote:
> > > If it's "only" the s/Lx/L/g, then that could be done with a
> > > configure check for the special case of antique nroff, and a
> > > substitution for make-sed.sh
> >
> > That's true. In my opinion 'x' is too nice a feature to do without
> > unless one has to, so it's worth complicating your CF_MAN_PAGES
> > Autoconf macro to take care of it.
...I've taken a pass over every tbl(1) region in the ncurses man pages,
and am preparing a bunch of minor fixups.
26cbbe6b3 man/captoinfo.1m: Clarify tbl portability comment.
a1e560fe4 man/menu.3x: Delete extra spaces before tabs.
cd7ebb5ef man/{form,menu}.3x: Fix table style nit.
820fd7165 man/*: Respell table formats.
ae1cce74e man/user_caps.5: Tweak table format.
1d3d8bef9 man/curs_{terminfo,util}.3x: Tweak table formats.
b59c6f28e include/Caps: Prevent page break in table start.
I used the following technique to extract all the table definitions for
inspection.
$ sed -n '/^\.TS/,/\.$/p' include/* man/*| grep -Ev '(TS|center|tab)'
The foregoing forthcoming patches clean up inconsistencies.
Next, it's looking to me like we can do better than just 's/Lx/L/g'.
What I _think_ we can do is 's/Lx/Lw(24n)/'.
You don't need 'g' because only one 'x' column modifier appears in any
row of any table in the ncurses man pages; that's to work around DWB 3.3
tbl itself. (It still throws a spurious warning, and has for as long as
'x' has been present in the tables.[1])
28n is how much line length is left over after subtracting from 65n the
widths of the other columns in the most cramped tables in the corpus:
the terminfo capability lists. 65n is the line length that AT&T troff
(including DWB troff) and its descendants in System V and Plan 9 use.
Lb Cb S Lb
Lb Lb Lb Lb
Lbw(25n)2 Lbw(8n)2 Lb2 Lx.
The third column is for termcap codes; its width is never more than 2.
65-(25+2+8+2+2+2)=24
These appear to be the most demanding tables in the corpus. My thinking
is that we can perform the foregoing substitution and preserve
equivalent results to 'x' in nroff mode for less featureful tbl
programs, and still have better-than-default column widths for text
blocks in every other table in the ncurses man pages. Lesk in CSTR #49
(1976, revised 1979)--and the GNU tbl man page--present the formula for
text block width computation.
(GNU) tbl(1):
Text blocks
...
If w or x modifiers are not specified for all columns of a text
block’s span, the default length of the text block (more precisely,
the line length used to process the text block’s diversion) is
computed as L×C/(N+1), where L is the current line length, C the
number of columns spanned by the text block, and N the number of
columns in the table. ...
Assuming a 2 column table (ncurses has no 1 column tables, and seems
never to use text blocks in spanned columns), that default is
(65n*1)/(2+1) = 21n. 24n is wider/better. For tables with more
columns, the result should be better still--long as they don't overset.
I haven't submitted patches for this yet because I need to test my
suspicion. The aforementioned ones were to get things in place so I
could perform my proposed substitution and compare the resuling outputs
using my usual battery of formatters. I think I'll be testing Plan 9
from User Space more often going forward as a proxy for Solaris 10. On
the other hand, I've also started looking into adding support for 'x'
(on at most one column per table, just like DWB 3.3) to P9US by cribbing
code from DWB 3.3, but it's not trivially easy because DWB apparently
decided to heavily refactor tbl at some point, which maybe explains why
this feature didn't cross-pollinate back into Plan 9 35 years ago. So
far the P9US guys have been really receptive to my suggestions regarding
troff and man(7).
Consequently, maybe I should install Dell SVr4 Unix into a virtual
machine and play with that when I need an authentic System V experience.
I've kind of been wanting to do that anyway.
https://virtuallyfun.com/wordpress/2020/12/01/dell-unix-on-86box/
I'll follow up when I know whether my 's/Lx/Lw(24n)/' trick works.
Regards,
Branden
[1] In the course of composing this email, I found what I think is a
near-minimal reproducer for DWB 3.3 tbl's spurious warning.
$ cat /tmp/dwb-tbl-blunder.roff
.TS
Lx.
table
.TE
.TS
tab(@);
L Lx.
second@table
.TE
$ DWBHOME=~/dwb ~/dwb/bin/tbl /tmp/dwb-tbl-blunder.roff >/dev/null
tbl: File /tmp/dwb-tbl-blunder.roff, line 7: Warning: Too many columns with 'x'
modifier.
I'll bet the DWB 3.x guys forgot to reset a variable when processing
multiple table regions in a document.
Nils-Peter Nelson, I accuse YOU!
But maybe it was Jaap Akkerhuis.
Or someone else.
https://lists.gnu.org/archive/html/groff/2022-12/msg00097.html
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