master a8a3fd8 2/2: Add macro `seq-setq`.

[Lars Ingebrigtsen]

branch: master
commit a8a3fd8f8e27089ac46bf98e534529ff03f679a5
Author: Earl Hyatt <okamsn@protonmail.com>
Commit: Lars Ingebrigtsen <larsi@gnus.org>

    Add macro `seq-setq`.
    
    * doc/lispref/sequences.texi (seq-setq): Document this macro.
    
    * test/lisp/emacs-lisp/seq-tests.el (test-seq-setq):
    Test this macro (bug#50053).
---
 doc/lispref/sequences.texi        | 17 +++++++++++++++++
 test/lisp/emacs-lisp/seq-tests.el | 24 ++++++++++++++++++++++++
 2 files changed, 41 insertions(+)

diff --git a/doc/lispref/sequences.texi b/doc/lispref/sequences.texi
index 20816ce..257f5d1 100644
--- a/doc/lispref/sequences.texi
+++ b/doc/lispref/sequences.texi
@@ -1128,6 +1128,23 @@ assigned to variables as if by @code{setq} instead of as 
in a
 @end example
 @end defmac
 
+@defmac seq-setq var-sequence val-sequence
+@cindex sequence destructuring
+  This macro works similarly to @code{seq-let}, except that values are
+assigned to variables as if by @code{setq} instead of as in a
+@code{let} binding.
+
+@example
+@group
+(let ((a nil)
+      (b nil))
+  (seq-setq (_ a _ b) '(1 2 3 4))
+  (list a b))
+@result{} (2 4)
+@end group
+@end example
+@end defmac
+
 @defun seq-random-elt sequence
   This function returns an element of @var{sequence} taken at random.
 
diff --git a/test/lisp/emacs-lisp/seq-tests.el 
b/test/lisp/emacs-lisp/seq-tests.el
index 44e855e..5217921 100644
--- a/test/lisp/emacs-lisp/seq-tests.el
+++ b/test/lisp/emacs-lisp/seq-tests.el
@@ -407,6 +407,30 @@ Evaluate BODY for each created sequence.
     (should (null b))
     (should (null c))))
 
+(ert-deftest test-seq-setq ()
+  (with-test-sequences (seq '(1 2 3 4))
+    (let (a b c d e)
+      (seq-setq (a b c d e) seq)
+      (should (= a 1))
+      (should (= b 2))
+      (should (= c 3))
+      (should (= d 4))
+      (should (null e)))
+    (let (a b others)
+      (seq-setq (a b &rest others) seq)
+      (should (= a 1))
+      (should (= b 2))
+      (should (same-contents-p others (seq-drop seq 2)))))
+  (let ((a)
+        (seq '(1 (2 (3 (4))))))
+    (seq-setq (_ (_ (_ (a)))) seq)
+    (should (= a 4)))
+  (let (seq a b c)
+    (seq-setq (a b c) seq)
+    (should (null a))
+    (should (null b))
+    (should (null c))))
+
 (ert-deftest test-seq-min-max ()
   (with-test-sequences (seq '(4 5 3 2 0 4))
     (should (= (seq-min seq) 0))