Hi Dave, At 2026-11-01T22:58:55-0600, Dave Kemper wrote: > On Thu, Aug 6, 2026 at 8:57 AM G. Branden Robinson > <[email protected]> wrote: > > To further/over- qualify this point, mom(7) is giving the formatter > > something to format by generating some embedded PostScript. > > ...embedded PostScript that does some internal initialization and puts > nothing on the page.
I take your word for it, as I haven't studied, and would be no wiser if
I tried to without first reading up considerably on the PostScript
language, which I don't know. Stack-based. Kinda Forthy. 'sall I know.
> It's not obvious to readers that this qualifies as "something to
> format."
No, and it wasn't to me, either.
> Naively, one could see it as akin to a roff file that contains only
> .nr lines; both are setting the stage for a show that never
> materializes.
Okay.
> I understand why one produces output while the other doesn't, but I
> don't think the line about it in the manual captures the difference.
> Nor do I think it needs to; this section is about how groff differs
> from other troffs. AT&T troff always produces output; groff does not
> always. For the purposes of pointing out that difference, there's
> little need to get into the minutiae of what constitutes "something to
> format."
Well, I guess what we need to do is give Peter something Deri also
needs: an enhanced `fl` ("flush") request that essentially says "I'm
going to perform surgery on the page now, but the output driver can
trust me to modify only the following elements of the page state (which
can be the empty set)".
https://savannah.gnu.org/bugs/?66187
Alternatively, maybe mom(7) could define a macro that emits the prolog,
then nullifies itself, and call it as the first thing in its default
header trap (and whatever unconditional stuff it holds on to when the
user redefines the header).
This way, mom(7) would not start the document if there was nothing to
format, but would always get that prolog out if there was.
I'd offer an example, but (a) I've never tried to get up to this sort of
device command tomfoolery and (b) I know almost nothing about mom(7)'s
internals.
But I'm happy to field questions if people don't know what I'm talking
about.
Regards,
Branden
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