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| | ;;; compat.el --- Pseudo-Compatibility for Elisp -*- lexical-binding: t; -*-
;; Copyright (C) 2021-2024 Free Software Foundation, Inc.
;; Author: \
;; Philip Kaludercic <philipk@posteo.net>, \
;; Daniel Mendler <mail@daniel-mendler.de>
;; Maintainer: \
;; Daniel Mendler <mail@daniel-mendler.de>, \
;; Compat Development <~pkal/compat-devel@lists.sr.ht>,
;; emacs-devel@gnu.org
;; URL: https://github.com/emacs-compat/compat
;; Keywords: lisp, maint
;; This program is free software; you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.
;; This program is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;; GNU General Public License for more details.
;; You should have received a copy of the GNU General Public License
;; along with this program. If not, see <https://www.gnu.org/licenses/>.
;;; Commentary:
;; The Compat package on ELPA provides forward-compatibility
;; definitions for other packages. While mostly transparent, a
;; minimal API is necessary whenever core definitions change calling
;; conventions (e.g. `plist-get' can be invoked with a predicate from
;; Emacs 29.1 onward). For core packages on ELPA to be able to take
;; advantage of this functionality, the macros `compat-function' and
;; `compat-call' have to be available in the core, usable even if
;; users do not have the Compat package installed, which this file
;; ensures.
;; A basic introduction to Compat is given in the Info node `(elisp)
;; Forwards Compatibility'. Further details on Compat are documented
;; in the Info node `(compat) Top' (installed along with the Compat
;; package) or read the same manual online:
;; https://elpa.gnu.org/packages/doc/compat.html.
;; Note that Compat is NOT a core package and this file is NOT
;; available on GNU ELPA.
;;; Code:
(defmacro compat-function (fun)
"Return compatibility function symbol for FUN.
This is a pseudo-compatibility stub for core packages on ELPA,
that depend on the Compat package, whenever the user doesn't have
the package installed on their current system."
`#',fun)
(defmacro compat-call (fun &rest args)
"Call compatibility function or macro FUN with ARGS.
This is a pseudo-compatibility stub for core packages on ELPA,
that depend on the Compat package, whenever the user doesn't have
the package installed on their current system."
(cons fun args))
;;;; Clever trick to avoid installing Compat if not necessary
;; The versioning scheme of the Compat package follows that of Emacs,
;; to indicate what version of Emacs is being supported. For example,
;; the Compat version number 29.2.3.9 would attempt to provide
;; compatibility definitions up to Emacs 29.2, while also designating
;; that this is the third major release and ninth minor release of
;; Compat, for the specific Emacs release.
;; The package version of this file is specified programmatically,
;; instead of giving a fixed version in the header of this file. This
;; is done to ensure that the version of compat.el provided by Emacs
;; is always corresponds to the current version of Emacs. In addition
;; to the major-minor version, a large "major release" makes sure that
;; the built-in version of Compat is always preferred over an external
;; installation. This means that if a package specifies a dependency
;; on Compat which matches the current version of Emacs that is being
;; used, no additional dependencies have to be downloaded.
;;
;; Further details and background on this file can be found in the
;; bug#66554 discussion.
;;;###autoload (push (list 'compat
;;;###autoload emacs-major-version
;;;###autoload emacs-minor-version
;;;###autoload 1.0e+INF)
;;;###autoload package--builtin-versions)
(provide 'compat)
;;; compat.el ends here
|