Re: mom: .START macro resets page dimensions

[Serge Baumer]

Peter Schaffter writes:
> On Mon, Mar 23, 2020, Serge Baumer wrote:
> > In the om.tmac, the .START macro calls .DEFAULTS unconditionally.  Here
> > are few lines of code from the very beginning of the .DEFAULTS
> > definition:
> > 
> > .    if !\\n[#DOC_TYPE]=5 \{\
> > .       ie !d $PAPER .PAPER LETTER
> > .       el .PAPER \\*[$PAPER]
> > .    \}
> > 
> > They are introduced by a commit dated 2018-03-04 to replace the more
> > simple
> > 
> > .    if !d $PAPER .PAPER LETTER
> > 
> > Thus, the new code is in the official 1.22.4 but not in earlier groff.
> > 
> > So, what we get here if we're not making slides (i.e. #DOC_TYPE != 5)
> > but have used .PAGE or any of .PAGEWIDTH, .PAGELENGTH separately before
> > .START.  If we haven't used .PAPER yet, it's called here with "LETTER",
> > resetting our custom page dimensions.  But if we'd called .PAPER, say,
> > before making page size tweaks: it's called again now, destroying our
> > previous work all the same.  So, we have a chance to setup our own page
> > size only with slides.
> 
> It's astounding how long a bug like this can hang around before it's
> discovered.  There are two culprits.  The first is that mom has
> been setting the default papersize (letter) in om.tmac itself with
> '.PAPER LETTER' when she should be calling PAGEWIDTH and PAGELENGTH
> separately.  The second is that the DEFAULTS clause, above, is
> unnecessary.  It's cruft from testing that I neglected to remove.
> When these issues are corrected, PAGELENGTH, PAGEWIDTH, and PAGE
> behave as expected.
> 
> One thing to be wary of: PAGEWIDTH only sets the width of the
> physical page.  It does not in/decrease the line length (an
> assumption mom does not make), and must be done either by giving an
> explicit R_MARGIN or an explicit LL.

:) Yeah, I got it after а day or two of reasoning WHY that page height
extends to A4/Letter one while width remains mine (my pages are mostly
pocket e-book reader mini-pages, and I use .PAGE with the full set of
args).  Then I said: well, man, what you see is not page width. It's
line length.

> > I didn't report this as a bug because I'm not sure that here's no
> > some sort of planned behaviour and that I didn't miss some info.
> > I can create a ticket though.
> 
> It is a bug.  No need to create a ticket.  Most mom bug reports come
> to me directly and go into the BUGS file.

Ok, all reports by mail, as said in BUGS.

> I'll make the necessary changes to the om.tmac in the groff
> repo and to the tarball at the mom site within a day or two.  If
> you're in a hurry, you can make the changes yourself.  Search
> through om.tmac for the text "Set up a default papersize".  Remove
> the line beneath, '.PAPER LETTER', and replace it with
> 
>   .PAGEWIDTH 8.5i
>   .PAGELENGTH 11i
> 
> then remove entirely the clause in DEFAULTS, above.

Good. Thanks for the reply, Peter, and thank you for mom.

--
Best regards,
Serge Baumer