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-rw-r--r--guix/deprecation.scm89
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+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2019 Ludovic Courtès <ludo@gnu.org>
+;;;
+;;; This file is part of GNU Guix.
+;;;
+;;; GNU Guix 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.
+;;;
+;;; GNU Guix 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 GNU Guix. If not, see <http://www.gnu.org/licenses/>.
+
+(define-module (guix deprecation)
+ #:use-module (guix i18n)
+ #:use-module (ice-9 format)
+ #:export (define-deprecated
+ without-deprecation-warnings
+ deprecation-warning-port))
+
+;;; Commentary:
+;;;
+;;; Provide a mechanism to mark bindings as deprecated.
+;;;
+;;; We don't reuse (guix ui) mostly to avoid pulling in too many things.
+;;;
+;;; Code:
+
+(define deprecation-warning-port
+ ;; Port where deprecation warnings go.
+ (make-parameter (current-warning-port)))
+
+(define (source-properties->location-string properties)
+ "Return a human-friendly, GNU-standard representation of PROPERTIES, a
+source property alist."
+ (let ((file (assq-ref properties 'filename))
+ (line (assq-ref properties 'line))
+ (column (assq-ref properties 'column)))
+ (if (and file line column)
+ (format #f "~a:~a:~a" file (+ 1 line) column)
+ (G_ "<unknown location>"))))
+
+(define* (warn-about-deprecation variable properties
+ #:key replacement)
+ (format (deprecation-warning-port)
+ (G_ "~a: warning: '~a' is deprecated~@[, use '~a' instead~]~%")
+ (source-properties->location-string properties)
+ variable replacement))
+
+(define-syntax define-deprecated
+ (lambda (s)
+ "Define a deprecated variable or procedure, along these lines:
+
+ (define-deprecated foo bar 42)
+ (define-deprecated (baz x y) qux (qux y x))
+
+This will write a deprecation warning to DEPRECATION-WARNING-PORT."
+ (syntax-case s ()
+ ((_ (proc formals ...) replacement body ...)
+ #'(define-deprecated proc replacement
+ (lambda* (formals ...) body ...)))
+ ((_ variable replacement exp)
+ (identifier? #'variable)
+ (with-syntax ((real (datum->syntax
+ #'variable
+ (symbol-append '%
+ (syntax->datum #'variable)
+ '/deprecated))))
+ #`(begin
+ (define real
+ (begin
+ (lambda () replacement) ;just to ensure it's bound
+ exp))
+
+ (define-syntax variable
+ (lambda (s)
+ (warn-about-deprecation 'variable (syntax-source s)
+ #:replacement 'replacement)
+ (syntax-case s ()
+ ((_ args (... ...))
+ #'(real args (... ...)))
+ (id
+ (identifier? #'id)
+ #'real))))))))))