Re: [Groff] W.: [bug #42978] tbl does not restore the tab settings

[Bjarni Ingi Gislason]

On Wed, Aug 13, 2014 at 10:03:06PM +0200, Carsten Kunze wrote:
[One long line reformatted]
> tbl(1) may be not in charge of this.  This is a function of the
> macro package.  AFAIK it is not possible for the preprocessor to read
> the tab positions (for restoring it).  So *you* should restore them
> (maybe some macro packages do it for you).
> 
>

  I did make a change to the "an-old.tmac" file to preserve the tab
settings.  I checked other files and they do also contain the TS/TE
macros.  Instead of making the same change in more than one place, I
find it would be simpler to make the changes in one place, "tbl".


--- an-old.tmac 2014-08-10 01:59:46.000000000 +0000
+++ an-old.tmac.new     2014-08-14 01:34:43.000000000 +0000
@@ -614,12 +614,19 @@
 .    ll 1000n
 .  \}
 .  HTML-IMAGE
+.  ds an-TS-tab \\n[.tabs]
 ..
 .
 .de1 T&
 ..
 .
 .de1 TE
+.  ie dan-TS-tab \{\
+.    ta \\*[an-TS-tab]
+.    rr an-TS-tab
+.  \}
+.  el \
+.    tm Macro TE: Macro TS has not been used before it
 .  HTML-IMAGE-END
 .  if \\n[an-html] \
 .    ll \\n[an-TS-ll]u


  So these added lines to "an-old.tmac" could instead be added to the
output of "tbl", with the name of the string variable adjusted to the
conventions of "tbl", and the test for the variable (in TE) and its
removal can be dropped.

  The change of tab setting is not documented in the manual of "tbl".

  The purpose of changing the tab setting ist not clear to me, as tabs
are not used in the output of "tbl".  Such changes are internal ones
and should therefore not be available outside of it, except if it is a
documented feature!  And it should then be explained for what it is
good (better) for!

[...]

-- 
Bjarni I. Gislason