classdef MyClass < handle
| Parameter | Description |
|---|---|
| none | handle is used as a superclass, not called directly. |
| Parameter | Description |
|---|---|
| none | handle is used as a superclass, not called directly. |
handle is the abstract base class from which every handle class derives. A class declared as classdef MyClass < handle has reference semantics: variables that hold the object are references to a single underlying instance rather than independent copies.
Assigning a handle object to another variable, or passing it to a function, copies the reference, not the data. All references then observe the same property values, and a change made through one reference is visible through every other reference to the same object.
This differs from a value class (the default when no superclass is specified), where each assignment produces an independent copy.
Deriving from handle also provides the common handle services: lifetime management with delete and isvalid, equality and relational comparison of references, and the reflection, event, listener and dynamic-property mechanisms exposed by the related handle subclasses.
To obtain an independent copy of a handle object, derive the class from nelson.mixin.Copyable and use its copy method.
d = [tempdir(), 'nelson_help_handle/'];
mkdir(d);
filewrite([d, '/NelsonHelpHandleCounter.m'], ["classdef NelsonHelpHandleCounter < handle"; " properties"; " Count = 0"; " end"; "end"]);
addpath(d);
a = NelsonHelpHandleCounter();
b = a; % b references the same object as a
b.Count = 5;
a.Count % 5: a and b share the same instance
isvalid(a) % true
delete(a);
isvalid(b) % false: the shared object has been deleted| Version | Description |
|---|---|
| 2.0.0 | initial version |