bug#60933: 30.0.50; ERC >5.5: Make buttonizing more extensible

[J.P.]

Tags: patch

ERC could really benefit from a more efficient, convenient, and flexible
means of modifying how words (mainly nicks) are buttonized in messages.

The approach being proposed here involves replacing the preferred type
of the third, "form" field in `erc-button-alist' entries. It's currently
an arbitrary "guard"-like sexp, which I'd like to deprecate in favor of
a function capable of rewriting the button itself. The deprecated form
would still be usable but would trigger a warning, going forward. A
special accommodation would be made for the constant t as well as for
special variables, whose values would be treated as booleans. This would
cover all existing default entries as currently used in client code.

The idea is for this new "rewriter" function to expect the bounds of the
button under consideration as input and to return something similar, or
nil, to indicate that the candidate ought to be skipped (as in not
buttonized). A separate variant with a different signature will be
required for nicknames since they're already treated specially. It'll be
passed additional arguments, such as `erc-server-user' and
`erc-channel-user' objects and a casemapped nickname, all of which are
already present in the caller's environment. Additionally, the values of
user options containing faces to be applied, such as
`erc-button-nickname-face' and `erc-button-face' will be free for the
changing, with all damage limited to the current button alone.

As an example of a possible application for this, I have included a
helper for displaying messages involving `substitute-command-keys'.
Other applications include button colorization and alternate display
text. Practical implementations of both are available on request.

The second patch contains the actual changes proposed above. The first
is only somewhat related but trivial enough to smuggle in with this set
(IMO). The last one I threw in on a whim. It adds additional flexibility
for third parties but will most likely be dropped or held back because
there's no immediate use for it in ERC's client code.

Thanks.


In GNU Emacs 30.0.50 (build 2, x86_64-pc-linux-gnu, GTK+ Version
 3.24.35, cairo version 1.17.6) of 2023-01-17 built on localhost
Repository revision: 281f48f19ecad706a639d57cb937afb0b97eded7
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12014000
System Description: Fedora Linux 36 (Workstation Edition)

Configured using:
 'configure --enable-check-lisp-object-type --enable-checking=yes,glyphs
 'CFLAGS=-O0 -g3'
 PKG_CONFIG_PATH=:/usr/lib64/pkgconfig:/usr/share/pkgconfig'

Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GPM GSETTINGS HARFBUZZ JPEG
JSON LCMS2 LIBOTF LIBSELINUX LIBSYSTEMD LIBXML2 M17N_FLT MODULES NOTIFY
INOTIFY PDUMPER PNG RSVG SECCOMP SOUND SQLITE3 THREADS TIFF
TOOLKIT_SCROLL_BARS WEBP X11 XDBE XIM XINPUT2 XPM GTK3 ZLIB

Important settings:
  value of $LANG: en_US.UTF-8
  value of $XMODIFIERS: @im=ibus
  locale-coding-system: utf-8-unix

Major mode: Lisp Interaction

Minor modes in effect:
  tooltip-mode: t
  global-eldoc-mode: t
  eldoc-mode: t
  show-paren-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  line-number-mode: t
  indent-tabs-mode: t
  transient-mark-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message mailcap yank-media puny dired
dired-loaddefs rfc822 mml mml-sec epa derived epg rfc6068 epg-config
gnus-util text-property-search mm-decode mm-bodies mm-encode mail-parse
rfc2231 mailabbrev gmm-utils mailheader sendmail rfc2047 rfc2045
ietf-drums mm-util mail-prsvr mail-utils erc iso8601 time-date
auth-source cl-seq eieio eieio-core cl-macs password-cache json subr-x
map thingatpt pp format-spec cl-loaddefs cl-lib erc-backend erc-goodies
erc-networks byte-opt gv bytecomp byte-compile erc-common erc-compat
erc-loaddefs rmc iso-transl tooltip cconv eldoc paren electric uniquify
ediff-hook vc-hooks lisp-float-type elisp-mode mwheel term/x-win x-win
term/common-win x-dnd tool-bar dnd fontset image regexp-opt fringe
tabulated-list replace newcomment text-mode lisp-mode prog-mode register
page tab-bar menu-bar rfn-eshadow isearch easymenu timer select
scroll-bar mouse jit-lock font-lock syntax font-core term/tty-colors
frame minibuffer nadvice seq simple cl-generic indonesian philippine
cham georgian utf-8-lang misc-lang vietnamese tibetan thai tai-viet lao
korean japanese eucjp-ms cp51932 hebrew greek romanian slovak czech
european ethiopic indian cyrillic chinese composite emoji-zwj charscript
charprop case-table epa-hook jka-cmpr-hook help abbrev obarray oclosure
cl-preloaded button loaddefs theme-loaddefs faces cus-face macroexp
files window text-properties overlay sha1 md5 base64 format env
code-pages mule custom widget keymap hashtable-print-readable backquote
threads dbusbind inotify lcms2 dynamic-setting system-font-setting
font-render-setting cairo move-toolbar gtk x-toolkit xinput2 x multi-tty
make-network-process emacs)

Memory information:
((conses 16 64390 6319)
 (symbols 48 8639 0)
 (strings 32 23673 1623)
 (string-bytes 1 685926)
 (vectors 16 15259)
 (vector-slots 8 209777 7692)
 (floats 8 24 35)
 (intervals 56 232 0)
 (buffers 976 10))

0001-5.6-Replace-Info-goto-node-with-info-in-erc-button-a.patch
Description: Text Data

0002-5.6-Add-erc-button-helper-for-substituting-command-k.patch
Description: Text Data

0003-5.6-Allow-erc-button-add-face-to-take-an-object.patch
Description: Text Data