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From: Douglas McIlroy <douglas.mcilroy@dartmouth.edu>
To: Branden Robinson <g.branden.robinson@gmail.com>
Cc: tuhs@minnie.tuhs.org
Subject: Re: [TUHS] troff environments, traps, and diversions (was: TeX and groff)
Date: Sat, 22 Jan 2022 11:02:10 -0500	[thread overview]
Message-ID: <CAKH6PiUB2Y+MaVuy4Z4K7d+DhUxc-7oTqrPbvf6xjx5er7Cypg@mail.gmail.com> (raw)
In-Reply-To: <CAN4uE+p=LpEJk8mMw7f+58VVnrKqRrx1dgEG8Ofqwc8LbPfgCQ@mail.gmail.com>

Branden,

I like these intro paragraphs and the elision of the ominous
adjective, "advanced".

>  An environment is created for the footnote so that it is set at a smaller typeface.

To avoid implying that one must create an environment with each
footnote and to illustrate that environments are collections of
settings, you might say something like this

> Switch to a previously created footnote environment with a smaller typeface and distinctive line length.

Doug

On Fri, Jan 21, 2022 at 9:34 PM Branden Robinson
<g.branden.robinson@gmail.com> wrote:
>
> On Tue, Jan 11, 2022 at 1:25 PM Lyndon Nerenberg (VE7TFX/VE6BBM)
> <lyndon@orthanc.ca> wrote:
> > A lot of people get turned off by how troff markup can often look like
> > line noise.  That's true, but if you spend the time to actually learn
> > the syntax (and it's really not that hard), you can't help but be
> > overwhelmed by the beauty of its self-consistency.  Although after
> > three decades I still can't wrap my head around traps and diversions
> > :-P
>
> It seems like a lot of people get stuck on the dread trio of traps,
> diversions, and environments.  Some old groff documentation did not, I
> think, help matters very much by characterizing them as "advanced" and
> particularly by comparing diversions to pointers in C.  I've been
> rewriting a lot of groff's documentation over the past five years.
>
> Here's my attempt to introduce these 3 concepts in the groff(7) page of
> the forthcoming 1.23 release.  Let me know how I can improve it.  (I
> retiterate that it's just an introduction--there is much more detail
> about all three later in the page and in groff's Texinfo manual, much of
> which has parallel content to its man pages.)
>
>        A further few language elements arise as page layouts become more
>        sophisticated and demanding.  Environments collect formatting
>        parameters like line length and typeface.  A diversion stores
>        formatted output for later use.  A trap is a condition on the
>        input or output, tested automatically by the formatter, that is
>        associated with a macro, causing it to be called when that
>        condition is fulfilled.
>
>        Footnote support often exercises all three of the foregoing
>        features.  A simple implementation might work as follows.  A pair
>        of macros is defined: one starts a footnote and the other ends
>        it.  The author calls the first macro where a footnote marker is
>        desired.  The macro establishes a diversion so that the footnote
>        text is collected at the place in the body text where its
>        corresponding marker appears.  An environment is created for the
>        footnote so that it is set at a smaller typeface.  The footnote
>        text is formatted in the diversion using that environment, but it
>        does not yet appear in the output.  The document author calls the
>        footnote end macro, which returns to the previous environment and
>        ends the diversion.  Later, after much more body text in the
>        document, a trap, set a small distance above the page bottom, is
>        sprung.  The macro called by the trap draws a line across the
>        page and emits the stored diversion.  Thus, the footnote is
>        rendered.
>
> Regards,
> Branden
> Foo
>
> On Tue, Jan 11, 2022 at 1:25 PM Lyndon Nerenberg (VE7TFX/VE6BBM) <lyndon@orthanc.ca> wrote:
>>
>> Dan Cross writes:
>>
>> > This is interesting; I've always felt like I could pick out troff pretty
>> > readily; I agree that TeX has a certain "look" to it (at least by default),
>> > but I always felt the same about troff as well.
>>
>> My guess this is more about how ms(7) does page layout.  I can spot
>> those documents from a mile away :-)
>>
>> But older versions of troff can often be spotted by how box corners
>> don't always line up properly.
>>
>> A lot of people get turned off by how troff markup can often look
>> like line noise.  That's true, but if you spend the time to actually
>> learn the syntax (and it's really not that hard), you can't help
>> but be overwhelmed by the beauty of its self-consistency.  Although
>> after three decades I still can't wrap my head around traps and
>> diversions :-P
>>
>> --lyndon

  reply	other threads:[~2022-01-22 16:03 UTC|newest]

Thread overview: 101+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-31 15:47 [TUHS] roff(7) Douglas McIlroy
2021-12-31 23:07 ` George Michaelson
2021-12-31 23:40   ` Larry McVoy
2022-01-01  0:56     ` [TUHS] TeX and groff (was: roff(7)) Greg 'groggy' Lehey
2022-01-01  3:15       ` Larry McVoy
2022-01-10 19:00         ` Blake McBride
2022-01-10 20:21           ` Jon Forrest
2022-01-11 22:48             ` Blake McBride
2022-01-11 23:18               ` Larry McVoy
2022-01-12  1:19                 ` Dave Horsfall
2022-01-12  1:46                 ` Blake McBride
2022-01-12  2:12                 ` Bakul Shah
2022-01-12 15:49                   ` Larry McVoy
2022-01-12 16:22                     ` Adam Thornton
2022-01-12  0:06               ` Jon Steinhart
2022-01-12  1:48                 ` Blake McBride
2022-01-12  0:29               ` Nemo Nusquam
2022-01-12  1:53                 ` Blake McBride
     [not found]               ` <E3CC4B8A-4E88-4339-A4D3-4ED26BA80620@gmail.com>
2022-01-12  0:44                 ` Jon Forrest
2022-01-12  2:00                   ` Blake McBride
2022-01-12  2:10                     ` David Arnold
2022-01-12  2:26                       ` Adam Thornton
2022-01-12 19:54                     ` John Cowan
2022-01-13 10:13                       ` Thomas Paulsen
2022-01-13 20:00                         ` John Cowan
2022-01-10 20:33           ` Larry McVoy
2022-01-10 20:37             ` Richard Salz
2022-01-10 21:04               ` Dan Cross
2022-01-10 21:48                 ` Nemo Nusquam
2022-01-11  2:25                 ` Lyndon Nerenberg (VE7TFX/VE6BBM)
2022-01-11  2:47                   ` Larry McVoy
2022-01-22  2:34                   ` [TUHS] troff environments, traps, and diversions (was: TeX and groff) Branden Robinson
2022-01-22 16:02                     ` Douglas McIlroy [this message]
2022-01-23 19:45                       ` Jon Steinhart
2022-01-23 22:26                       ` Jon Steinhart
2022-01-11  1:52               ` [TUHS] Recognizing TeX (was: TeX and groff (was: roff(7))) Greg 'groggy' Lehey
2022-01-12  1:19             ` [TUHS] TeX and groff (was: roff(7)) Mary Ann Horton
2022-01-12  2:03               ` Blake McBride
2022-01-12  2:10               ` Bakul Shah
2022-01-12  3:44                 ` Dan Cross
2022-01-12 16:48               ` Steffen Nurpmeso
2022-01-10 20:46           ` Steffen Nurpmeso
2022-01-11  1:59           ` [TUHS] Demise of " Greg 'groggy' Lehey
2022-01-11  2:13             ` Lyndon Nerenberg (VE7TFX/VE6BBM)
2022-01-11  2:42               ` Larry McVoy
2022-01-11  5:12                 ` Greg 'groggy' Lehey
2022-01-11  5:59                   ` John Labovitz
2022-01-11  8:57                   ` arnold
2022-01-11 20:15                     ` Jon Steinhart
2022-01-11 20:22                       ` Larry McVoy
2022-01-11 20:26                         ` Jon Steinhart
2022-01-11 20:36                           ` Larry McVoy
2022-01-11 20:41                             ` Jon Steinhart
2022-01-11 20:49                               ` Larry McVoy
2022-01-11 21:03                                 ` Jon Steinhart
2022-01-11  8:50                 ` arnold
2022-01-11 14:00                   ` Larry McVoy
2022-01-12 23:22                     ` [TUHS] troff or groff? (was: Demise of TeX and groff (was: roff(7))) Greg 'groggy' Lehey
2022-01-12 23:29                       ` Greg 'groggy' Lehey
2022-01-12 23:32                       ` Larry McVoy
2022-01-11 15:47                 ` [TUHS] Demise of TeX and groff (was: roff(7)) Clem Cole
2022-01-11 16:55                   ` Richard Salz
2022-01-11 18:49                     ` Clem Cole
2022-01-11 19:20                   ` John Cowan
2022-01-11 20:06                     ` Clem Cole
2022-01-11 23:57                       ` Warner Losh
2022-01-12  0:03                         ` Warner Losh
2022-01-12  8:54                       ` arnold
2022-01-12 15:17                         ` Clem Cole
2022-01-12 16:33                         ` Dan Cross
2022-01-12 18:06                           ` [TUHS] *roff history as told to GNU G. Branden Robinson
2022-01-12 18:34                             ` Dan Halbert
2022-01-12 22:48                               ` Clem Cole
2022-01-12 23:27                                 ` Charles H. Sauer
2022-01-13  0:35                                   ` Adam Thornton
2022-01-12 20:01                             ` Dan Cross
2022-01-12 22:32                             ` Clem Cole
2022-01-13  2:38                             ` John Labovitz
2022-01-13  7:42                               ` Lars Brinkhoff
2022-01-13 13:47                                 ` John Labovitz
2022-01-12  8:48                   ` [TUHS] Demise of TeX and groff (was: roff(7)) arnold
2022-01-12 15:51                     ` Larry McVoy
2022-01-12 15:57                       ` Clem Cole
2022-01-12 15:56                     ` Clem Cole
2022-01-11  3:22               ` Adam Thornton
2022-01-12  0:32             ` Nemo Nusquam
2022-01-01 20:00     ` [TUHS] roff(7) [ and other related stuff ] Jon Steinhart
2022-01-02  0:12       ` Larry McVoy
2022-01-02  1:04         ` John Cowan
2022-01-02  1:20           ` Larry McVoy
2022-01-02  1:47             ` Steve Nickolas
2022-01-02  2:12               ` Larry McVoy
2022-01-02  3:56               ` Jon Steinhart
2022-01-02  1:48             ` Jon Steinhart
2022-01-02  3:04             ` John Cowan
2022-01-02  3:30               ` Warner Losh
2022-01-01  1:11   ` [TUHS] roff(7) Phil Budne
2022-01-01  1:17     ` Chris Torek
2022-01-01  3:06       ` Larry McVoy
2022-01-01  3:34       ` George Michaelson
2022-01-05 21:15   ` Tony Finch

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