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db195116a4
* lisp/emacs-lisp/compat.el: Add stub file with minimal definitions, so that core packages, that haven't been installed from ELPA, can make use of the public API and use more recent function signatures. * lisp/progmodes/python.el (compat): Remove 'noerror flag, because Compat can now be required without the real package being available. * doc/lispref/package.texi (Forwards-Compatibility): Mention Compat and link to the manual. * etc/NEWS: Document change. (Bug#66554)
93 lines
3.9 KiB
EmacsLisp
93 lines
3.9 KiB
EmacsLisp
;;; compat.el --- Stub of the Compatibility Library -*- lexical-binding: t; -*-
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;; Copyright (C) 2021-2024 Free Software Foundation, Inc.
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;; Author: \
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;; Philip Kaludercic <philipk@posteo.net>, \
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;; Daniel Mendler <mail@daniel-mendler.de>
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;; Maintainer: \
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;; Daniel Mendler <mail@daniel-mendler.de>, \
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;; Compat Development <~pkal/compat-devel@lists.sr.ht>,
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;; emacs-devel@gnu.org
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;; URL: https://github.com/emacs-compat/compat
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;; Keywords: lisp, maint
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;; This program is free software; you can redistribute it and/or modify
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;; it under the terms of the GNU General Public License as published by
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;; the Free Software Foundation, either version 3 of the License, or
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;; (at your option) any later version.
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;; This program is distributed in the hope that it will be useful,
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;; GNU General Public License for more details.
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;; You should have received a copy of the GNU General Public License
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;; along with this program. If not, see <https://www.gnu.org/licenses/>.
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;;; Commentary:
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;; The Compat package on ELPA provides forward-compatibility
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;; definitions for other packages. While mostly transparent, a
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;; minimal API is necessary whenever core definitions change calling
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;; conventions (e.g. `plist-get' can be invoked with a predicate from
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;; Emacs 29.1 onward). For core packages on ELPA to be able to take
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;; advantage of this functionality, the macros `compat-function' and
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;; `compat-call' have to be available in the core, usable even if
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;; users do not have the Compat package installed, which this file
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;; ensures.
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;; A basic introduction to Compat is given in the Info node `(elisp)
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;; Forwards Compatibility'. Further details on Compat are documented
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;; in the Info node `(compat) Top' (installed along with the Compat
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;; package) or read the same manual online:
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;; https://elpa.gnu.org/packages/doc/compat.html.
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;;; Code:
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(defmacro compat-function (fun)
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"Return compatibility function symbol for FUN.
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This is a pseudo-compatibility stub for core packages on ELPA,
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that depend on the Compat package, whenever the user doesn't have
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the package installed on their current system."
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`#',fun)
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(defmacro compat-call (fun &rest args)
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"Call compatibility function or macro FUN with ARGS.
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This is a pseudo-compatibility stub for core packages on ELPA,
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that depend on the Compat package, whenever the user doesn't have
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the package installed on their current system."
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(cons fun args))
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;;;; Clever trick to avoid installing Compat if not necessary
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;; The versioning scheme of the Compat package follows that of Emacs,
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;; to indicate the version of Emacs, that functionality is being
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;; provided for. For example, the Compat version number 29.2.3.9
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;; would attempt to provide compatibility definitions up to Emacs
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;; 29.2, while also designating that this is the third major release
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;; and ninth minor release of Compat, for the specific Emacs release.
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;; The package version of this file is specified programmatically,
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;; instead of giving a fixed version in the header of this file. This
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;; is done to ensure that the version of compat.el provided by Emacs
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;; always corresponds to the current version of Emacs. In addition to
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;; the major-minor version, a large "major release" makes sure that
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;; the built-in version of Compat is always preferred over an external
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;; installation. This means that if a package specifies a dependency
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;; on Compat which matches the current or an older version of Emacs
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;; that is being used, no additional dependencies have to be
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;; downloaded.
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;;
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;; Further details and background on this file can be found in the
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;; bug#66554 discussion.
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;;;###autoload (push (list 'compat
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;;;###autoload emacs-major-version
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;;;###autoload emacs-minor-version
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;;;###autoload 9999)
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;;;###autoload package--builtin-versions)
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(provide 'compat)
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;;; compat.el ends here
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