Reimplement kvplist-merge as adviced by spacebat

Spacebat in the #emacs channel suggested to use the loop macro.
https://gist.github.com/4595042

3 files changed, 19 insertions, 13 deletions

diff --git a/README.creole b/README.creole
index d5e49ab..1dfd1aa 100644
--- a/README.creole
+++ b/README.creole
@@ -145,9 +145,10 @@ Filter the plist to just those matching //keys//.
 
 [[kvalist->filter-keys]] is actually used to do this work.
 
-=== kvplist->merge old-plist new-plist ===
+=== kvplist->merge &rest plists ===
 
-Merge the keys from new-plist into old-plist and return the new plist.
+Merge the 2nd and subsequent plists into the first, clobbering values set
+by lists to the left.
 
 === kvplist2->filter-keys plist2 &rest keys ===
 
diff --git a/kv-tests.el b/kv-tests.el
index 7cc6eed..adbaa49 100644
--- a/kv-tests.el
+++ b/kv-tests.el
@@ -186,4 +186,12 @@
     (kvplist-merge '(:key1 "value1" :key2 "old value")
                    '(:key2 "new value" :key3 "entirely new")))))
 
+(ert-deftest kvplist-merge-multiple ()
+  (should
+   (equal
+    '(:key1 "value1" :key2 "new value" :key3 "overwritten new one" :key4 "second entirely new")
+    (kvplist-merge '(:key1 "value1" :key2 "old value")
+                   '(:key2 "new value" :key3 "entirely new")
+                   '(:key3 "overwritten new one" :key4 "second entirely new")))))
+
 ;;; kv-tests.el ends here
diff --git a/kv.el b/kv.el
index 57958e1..2139b28 100644
--- a/kv.el
+++ b/kv.el
@@ -385,17 +385,14 @@ SEXP will describe the structure desired."
 
 (defalias 'map-bind 'kvmap-bind)
 
-(defun kvplist-merge (old new)
-  "Merges two plists. The keys from NEW will overwrite the ones in OLD."
-  (let ((key (car new))
-        (val (cadr new))
-        (new (cddr new)))
-    (while (and key val)
-      (setq old (plist-put old key val))
-      (setq key (car new))
-      (setq val (cadr new))
-      (setq new (cddr new)))
-    old))
+(defun kvplist-merge (&rest plists)
+  "Merge the 2nd and subsequent plists into the first, clobbering values set by lists to the left."
+  (let ((result (car plists))
+        (plists (cdr plists)))
+    (loop for plist in plists do
+          (loop for (key val) on plist by 'cddr do
+                (setq result (plist-put result key val))))
+    result))
 
 (provide 'kv)
 (provide 'dotassoc)