MATLAB Object-Oriented Programming

Methods for Handle Compatible Classes

In this section...

“Methods for Handle and Value Objects” on page 12-46

“Modify Value Objects in Methods” on page 12-46

Methods for Handle and Value Objects

Objects passed to methods of handle compatible classes can be either handle or value

objects. There are two different behaviors to consider when implementing methods for a

class that operate on both handles and values:

• If an input object is a handle object and the method alters the handle object, these
  changes are visible to all workspaces that contain the same handle.


• If an input object is a value object, then changes to the object made inside the method
  affect only the value inside the method workspace.

Handle compatible methods generally do not alter input objects because the effects of

such changes are not the same for handle and nonhandle objects.

See “Object Modification” on page 5-63 for information about modifying handle and value

objects.

Modify Value Objects in Methods

If a method operates on both handle and value objects, the method must return the

modified object. For example, the setTime method returns the object it modifies:

classdef (HandleCompatible) Util

% Utility class that adds a time stamp

properties

TimeStamp

end

methods

function obj = setTime(obj)

obj.TimeStamp = now;

end

end

end

12 How to Build on Other Classes