Time estimate shown in GUI as formatted string / Write to file made by class GCode's private methods

xs/xsp/Print.xsp

@@ -153,6 +153,8 @@ _constant()
         %code%{ RETVAL = &THIS->skirt; %};
     Ref<ExtrusionEntityCollection> brim()
         %code%{ RETVAL = &THIS->brim; %};
+    std::string estimated_print_time()
+        %code%{ RETVAL = THIS->estimated_print_time; %};
 
     PrintObjectPtrs* objects()
         %code%{ RETVAL = &THIS->objects; %};
@@ -281,17 +283,6 @@ Print::total_cost(...)
         }
         RETVAL = THIS->total_cost;
     OUTPUT:
-        RETVAL
-
-double
-Print::estimated_print_time(...)
-    CODE:
-        if (items > 1) {
-            THIS->estimated_print_time = (double)SvNV(ST(1));
-        }
-        RETVAL = THIS->estimated_print_time;
-    OUTPUT:
-        RETVAL
-        
+        RETVAL        
 %}
 };