Re: Changing header/footer font in mm

[Thomas Dupond]

"G. Branden Robinson" <g.branden.robinson@gmail.com> a écrit :
> Hi Jan,
>
> At 2024-04-24T07:53:51+0200, Jan Eden wrote:
>> On 2024-04-24 00:07, G. Branden Robinson wrote:
>> > At 2024-04-21T23:52:48-0500, G. Branden Robinson wrote:
>> > > For mm, what I would do is set up the mounting positions to replace
>> > > Times with Helvetica.
>> > > 
>> > > .fp 1 HR
>> > > .fp 2 HI
>> > > .fp 3 HB
>> > > .fp 4 HBI

Hello Branden,

This question is naive but why isn’t .fam implemented as a wrapping to
the .fp macro like:

.de fam
.fp 1 R \\$1R
.fp 2 I \\$1I
.fp 3 B \\$1B
.fp 4 BI \\$1BI
..

Of course this doesn’t implement the capability of going to the
previous font family with an empty .fam call.

>> > 
>> > I retract this advice.  Using ".fam H" early in the document (in
>> > groff 1.23.0) is better.
>> 
>> This did not work in groff 1.23.0 for the header/footer issue (with
>> `.fam H` as the very first request in the document), I had to use both
>> requests –
>> 
>> .fam H
>> .fp 1 H
>> 
>> – as suggested by Thomas.
>
> Ah, right.  Okay.  I un-retract the advice.  Yes, Thomas was right.
>
> The reason is that, quite apart from environment issues, groff mm is
> faithful to the DWB mm tradition in that internally it refers to fonts
> by mounting position rather than a named style, even though it has
> cognizance of only one family.[1]  Jörgen Hägg, the author groff mm,
> appears to have added some limited support for switching the font family
> to his multicolumn macro extensions, MULB/MULN/MULE, but it's not clear
> to me exactly how they work.  (Rather, I can read and understand the
> requests just fine but I'm not sure they're necessary...?  Perhaps this
> was the beginning of an unfinished idea.)
>
> This fact is totally separate from the environment stuff I was talking
> about earlier because, as I noted previously, the list of font mounting
> positions is global, and consistent among all environments.
>
> The concept of mounting positions is a fairly baroque aspect of troff
> and completely, as far as I know, a consequence of the hardware design
> of the C/A/T phototypesetter used by the Bell Labs CSRG.  They used this
> indirection to refer to fonts because the machine itself did.  You
> didn't have any idea what font's photographic plate would be loaded into
> the various positions of the typesetter's mechanical carousel.  One of
> your co-workers could scramble their order, ruining your document and
> you had no way of knowing until it was printed.
>
> I expect this didn't happen often, not with the imploding gaze of an
> office balrog to fear...
>
> I would prefer to wean groff mm off of explicit use of mounting
> positions altogether, but doing so is not a high-urgency project.
> (This also means it's good task for a contributor who wants a modestly
> sized project to learn with.  :) )
>
> Regards,
> Branden
>
> [1] I grepped and could find _no_ matches in our m.tmac for `ft [BIR]`,
>     `\\f[BIR] or `\\f\[[BIR]\]`.  Replacing "BIR" with "123" is more
>     fruitful.

-- 
Thomas