+ static PBD::Signal2<int,std::string,std::vector<std::string> > AmbiguousFileName;
+
+ void existence_check ();
+ virtual void prevent_deletion ();
+
+ /** Rename the file on disk referenced by this source to \param newname
+ */
+ int rename (const std::string& name);
+
+ virtual void close () = 0;
+
+ protected: