OOP Property attribute syntax

Hello

I've been given some code I can't quite follow and I can't seem to find any reference to an example on the net.

It is the following:

classdef classname < handle

      % Read-only handle properties

      properties(Access={?filename1, ?filename2, ?filename3})
          prop 1
          prop 2
          etc...etc...
      end

....etc etc

My questions are:

1) What does the "?" signify in the attribute section of the Properties call? I can't seem to search that and find an answer to it.

2) The {} brackets seem to indicate a cell array. However, I'm not sure what it's used for here though. Some documentation implies some sort of "meta class" and I haven't got a clue what that is about.

Admittedly I'm a novice in OOP and I'm really only a beginner at MATLAB as it is so I'm a bit lost here.

Any help would be appreciated. A real good clear example using this syntax would be of great help.

jom

Answer 1

[Steven Lord]

The syntax ?<name of class> creates a meta.class object, which is an object that contains information (metadata) about a MATLAB class. In this context, as the value for a property's Access attribute, they indicate that only methods of certain classes (the classes whose meta.class objects you specify) are allowed to get and/or set those properties.

This technique of restricting property access is a bit of an advanced maneuver, but the examples on this page may be simple enough to show you what's going on.