list-metadata: search-term is an optional argument, change the type f…

…rom string to (or string null).

classes.lisp

@@ -35,6 +35,9 @@
     :composer :performer :comment :disc :filename :any)
   "Types of tags for using in `search' and `find'")
 
+(deftype tag-type ()
+  `(member ,@*tag-types*))
+
 (defclass track ()
   ((file
     :initform nil :initarg :file :accessor file)

commands.lisp

@@ -243,20 +243,20 @@
 
 (defcommand find-tracks (type what)
   "Find tracks in the database with a case sensitive, exact match."
-  (assert (member type *tag-types*))
+  (check-args tag-type type)
   (check-args string what)
   (parse-list (send "find" type what) 'track))
 
 (defcommand list-metadata (metadata-1 &optional metadata-2 search-term)
   "List all metadata of `metadata-1'.
 If `metadata-2' & `search-term' are supplied,
 then list all `metadata-1' in which `metadata-2' has value `search-term'."
-  (check-args string search-term)
+  (check-args (or string null) search-term)
   (send "list" metadata-1 metadata-2 search-term))
 
 (defcommand search-tracks (type what)
   "Find tracks in the database with a case sensitive, inexact match."
-  (assert (member type *tag-types*))
+  (check-args tag-type type)
   (check-args string what)
   (parse-list (send "search" type what) 'track))
 

mpd.lisp

@@ -122,7 +122,7 @@
       (when (zerop (length string))
         (error 'mpd-error :text "Zero length argument."))
       (if (position #\Space string)
-          (format nil "~s" string)
+          (prin1-to-string string)
           string))))
 
 ;;; Macros