PIIODevice registration dramatically optimization

doc/examples/piiodevice.cpp

@@ -3,7 +3,7 @@ void _() {
 	
 //! [0]
 class SomeIO: public PIIODevice {
-	PIIODEVICE(SomeIO)
+	PIIODEVICE(SomeIO, "myio")
 public:
 	SomeIO(): PIIODevice() {}
 protected:
@@ -19,9 +19,8 @@ protected:
 		// write to your device here
 		return written_bytes;
 	}
-	PIString fullPathPrefix() const {return "myio";}
 	void configureFromFullPath(const PIString & full_path) {
-		// parse full_path and configure device there
+		// parse full_path and configure device here
 	}
 };
 REGISTER_DEVICE(SomeIO)