const classpetanque::SimpleChangesys::Obj petanque::Change petanque::SimpleChangeSimpleChangeexecuteSourcevirtual override Void execute(Editor editor)makeSourcenew make(Pos pos, Str oldText, Str newText)newTextSourceconst Str newTextoldTextSourceconst Str oldTextposSourceconst Pos postoStrSourcevirtual override Str toStr()undoSourcevirtual override Void undo(Editor editor)