Re: Should temporary indentation be ignored when centering?

[Bjarni Ingi Gislason]

On Sun, May 21, 2023 at 02:52:02AM -0500, G. Branden Robinson wrote:
> Hi all,
> 
> For just over 23 years, since commit e9b0d52dec, our Texinfo manual has
> claimed that temporary indentation is ignored when lines are being
> centered with the `ce` request.
> 
> But that is not the case in groff 1.22.4 or Git HEAD, and it's not true
> of DWB 3.3 troff or Heirloom Doctools troff, either.
> 
> It's not ignored by `rj` either.
> 
> I'll be pushing a commit to comment out this incorrect statement, rather
> than deleting it, because I think perhaps we should change this
> behavior.
> 
> Most of the time I don't think it is what a user would expect.
> 
> If you do use it, you have to double the amount of the temporary
> indentation to get what you would expect.  (The temporary indentation
> gets cut in half as part of the centering arithmetic, I think.)
> 
> Also, you can't use a negative temporary indentation (if doing so
> completely eats up more than the the normal indentation).  groff warns;
> the others don't, but all lay out the output identically.
> 
> $ cat ce2.roff
> .ce 4
> foo
> .ti -3n
> bar
> .ti 6n
> baz
> qux
> 
> $ DWBHOME=. ./bin/nroff ce2.roff |cat -s # or...
> $ ./bin/nroff ce2.roff |cat -s # Heirloom, or...
> $ nroff ./EXPERIMENTS/ce2.roff | cat -s # groff 1.22.4
>                                foo
>                                bar
>                                   baz
>                                qux
> 
> groff's warning, seen with '-wrange':
> troff: ./EXPERIMENTS/ce2.roff:3: warning: total indent cannot be negative
> 
> What should be done?

  The false statement in "doc/groff.texi" should be removed.

  If an indent is there, it affects finding the middle of a text in the
output line.

  One example does not proof anything.

  Expectations are imaginations.

####

.nr length \n(.lu/1n
Line length is \n[length]n
.br
.nr QQ 9*\w'0'u
12345678901234567890123456789012345678901234567890123456789012345678901234567890
\h'\n(QQu'1\h'\n(QQu'2\h'\n(QQu'3\h'\n(QQu'4\h'\n(QQu'5\h'\n(QQu'6\h'\n(QQu'7\h'\n(QQu'8
.br
.ce 4
foo
.\".ti -3n
barbar
.ti 6n
baz
qux
.pl \n(nlu

  Result:

troff:../testen/prof.temp.indent:5: warning [p 1, 0.2i]: cannot break line
troff:../testen/prof.temp.indent:6: warning [p 1, 0.3i]: cannot break line

Line length is 65n
12345678901234567890123456789012345678901234567890123456789012345678901234567890
         1         2         3         4         5         6         7         8
                               foo
                             barbar
                                  baz
                               qux

####

Ignoring indent does not make sense.