URL: <https://savannah.gnu.org/bugs/?66051>
Summary: [troff] permit special characters to have bespoke
hyphenation codes
Group: GNU roff
Submitter: gbranden
Submitted: Wed 31 Jul 2024 09:08:38 PM UTC
Category: Core
Severity: 1 - Wish
Item Group: Feature change
Status: None
Privacy: Public
Assigned to: None
Open/Closed: Open
Discussion Lock: Any
Planned Release: None
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Follow-up Comments:
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Date: Wed 31 Jul 2024 09:08:38 PM UTC By: G. Branden Robinson <gbranden>
This idea is a descendant of bug #42870, which asked for something a little
more modest.
The concept is this.
If we can do this...
.hcode ß ß
...why can't we do this?
.hcode \[ss] \[ss]
This has long produced a diagnostic.
$ printf '.hcode \\[ss] \\[ss]\n' | ~/groff-stable/bin/groff
troff:<standard input>:1: error: hyphenation code must be ordinary character
I suggested an answer in bug #66040, comment 9.
> Because the formatter doesn't know what [hyphenation code] value to give
[the special character]. Under the hood, [a hyphenation code] is just a
character code--in other words, on an ISO 8859 system, the hyphenation codes
for 'a' through 'z' are 97 through 122--but our documentation stands on its
head to avoid saying that. The trouble is that there is a potentially larger
space of _sui generis_ special characters, by which I mean ones that don't
belong to an equivalence class of a Basic Latin letter. [... The] German
Eszett [for example] is not. If we had an Icelandic locale, thorn and eth
would similarly have to have hyphenation codes above 127 decimal.
>
> The real fun comes when you add letters from multiple ISO 8859 character
sets. Before long you're going to have collisions.
>
> So it's good that our documentation does the headstand. We should not
disclose what the hyphenation code values _are_, we need only to ensure that
they sort into the correct equivalence classes, so that they then interoperate
as desired with the hyphenation patterns.
>
> When we get support for UTF-8-encoded hyphenation pattern files, things will
become straightforward again.
>
> In the meantime, what I think I will do is use a `static int` to mint a
sequence number (starting at 256) for hyphenation codes any time a special
character needs one _sui generis_.
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