tuned;

--- a/src/Pure/Thy/sessions.scala	Fri Mar 17 21:57:11 2017 +0100
+++ b/src/Pure/Thy/sessions.scala	Fri Mar 17 22:00:34 2017 +0100
@@ -599,6 +599,8 @@
       if (system_mode) Path.explode("~~/heaps/$ML_IDENTIFIER")
       else Path.explode("$ISABELLE_OUTPUT")
 
+    override def toString: String = "Store(output_dir = " + output_dir.expand + ")"
+
     def prepare_output() { Isabelle_System.mkdirs(output_dir + Path.basic("log")) }
 
 
@@ -624,11 +626,6 @@
           cat_lines(input_dirs.map(dir => "  " + dir.expand.implode)))
 
 
-    /* print */
-
-    override def toString: String = "Store(output_dir = " + output_dir.expand + ")"
-
-
     /* session info */
 
     def write_session_info(