branch: externals/compat
commit abe97399f840929e6cff55fe9f5fb9110b6a7c97
Author: Daniel Mendler <m...@daniel-mendler.de>
Commit: Daniel Mendler <m...@daniel-mendler.de>
compat-30: Add static-if
---
compat-30.el | 13 +++++++++++--
compat-tests.el | 9 +++++++++
compat.texi | 25 +++++++++++++++++++++++++
3 files changed, 45 insertions(+), 2 deletions(-)
diff --git a/compat-30.el b/compat-30.el
index 72110f23c0..3aaf99759e 100644
--- a/compat-30.el
+++ b/compat-30.el
@@ -22,8 +22,7 @@
;;; Code:
(eval-when-compile (load "compat-macs.el" nil t t))
-;; TODO Update to 29.1 as soon as the Emacs emacs-29 branch version bumped
-(compat-require compat-29 "29.0.90")
+(compat-require compat-29 "29.1")
;; TODO Update to 30.1 as soon as the Emacs emacs-30 branch version bumped
(compat-version "30.0.50")
@@ -56,5 +55,15 @@
tree)
tree)))
+(compat-defmacro static-if (condition then-form &rest else-forms) ;;
<compat-tests:static-if>
+ "A conditional compilation macro.
+Evaluate CONDITION at macro-expansion time. If it is non-nil,
+expand the macro to THEN-FORM. Otherwise expand it to ELSE-FORMS
+enclosed in a `progn' form. ELSE-FORMS may be empty."
+ (declare (indent 2) (debug (sexp sexp &rest sexp)))
+ (if (eval condition lexical-binding)
+ then-form
+ (cons 'progn else-forms)))
+
(provide 'compat-30)
;;; compat-30.el ends here
diff --git a/compat-tests.el b/compat-tests.el
index 1bb1f3ed35..98bb0d9028 100644
--- a/compat-tests.el
+++ b/compat-tests.el
@@ -75,6 +75,7 @@
(defmacro should-equal (a b)
`(should (equal ,a ,b)))
+;; TODO replace `compat-tests--if' with `static-if'
(defmacro compat-tests--if (cond then &rest else)
(declare (indent 2))
(if (eval cond t) then (macroexp-progn else)))
@@ -3049,5 +3050,13 @@
"(a (b ((c) . d) e) (f))"
"(a (b ((c) . d) e) (f))"))))))
+(ert-deftest compat-static-if ()
+ ;; TODO enable if CI Emacs 30 snapshot has been updated
+ (compat-tests--if (< emacs-major-version 30)
+ (progn
+ (should-equal "true" (static-if t "true"))
+ (should-not (static-if nil "true"))
+ (should-equal "else2" (static-if nil "true" "else1" "else2")))))
+
(provide 'compat-tests)
;;; compat-tests.el ends here
diff --git a/compat.texi b/compat.texi
index 178106c564..a6ea20b753 100644
--- a/compat.texi
+++ b/compat.texi
@@ -3348,6 +3348,31 @@ older than 30.1. Note that due to upstream changes, it
might happen
that there will be the need for changes, so use these functions with
care.
+@defmac static-if condition then-form else-forms...
+Test @var{condition} at macro-expansion time. If its value is
+non-@code{nil}, expand the macro to @var{then-form}, otherwise expand
+it to @var{else-forms} enclosed in a @code{progn}. @var{else-forms}
+may be empty.
+
+Here is an example of its use from CC Mode, which prevents a
+@code{defadvice} form being compiled in newer versions of Emacs:
+@example
+@group
+(static-if (boundp 'comment-line-break-function)
+ (progn)
+ (defvar c-inside-line-break-advice nil)
+ (defadvice indent-new-comment-line (around c-line-break-advice
+ activate preactivate)
+ "Call `c-indent-new-comment-line' if in CC Mode."
+ (if (or c-inside-line-break-advice
+ (not c-buffer-is-cc-mode))
+ ad-do-it
+ (let ((c-inside-line-break-advice t))
+ (c-indent-new-comment-line (ad-get-arg 0))))))
+@end group
+@end example
+@end defmac
+
@subsection Extended Definitions
These functions must be called explicitly via @code{compat-call},
since their calling convention or behavior was extended in Emacs 30.1:
