MATLAB Object-Oriented Programming

Code Patterns for subsref and subsasgn Methods

In this section...

“Customize Indexed Reference and Assignment” on page 17-21

“Syntax for subsref and subsasgn Methods” on page 17-21

“Indexing Structure Describes Indexing Expressions” on page 17-22

“Values of the Indexing Structure” on page 17-23

“Typical Patterns for Indexing Methods” on page 17-23

Customize Indexed Reference and Assignment

User-defined classes have the same indexing behaviors as that of built-in classes. Classes

can customize indexing operations by overloading the functions that MATLAB calls to

evaluate indexing expressions. Overload the subsref and subsasgn functions when you

want to define special behaviors for indexed reference and assignment.

For an overview of object indexing, see “Object Array Indexing” on page 17-15.

Syntax for subsref and subsasgn Methods

MATLAB calls the subsref and subsasgn methods of your class with these arguments.

Method Input Output

b = subsref(obj,s) • obj — Object or object

array used in indexing

expression

• s — Indexing structure

b — Result of indexing

expression

obj =

subsasgn(obj,s,b)

• obj — Object or object
  array used in indexing
  expression


• s — Indexing structure


• b — Value being assigned

obj — Object or object

array after assignment

Modifying Number of Arguments

If your class design requires that indexing operations return or assign a different number

of values than the number defined by the default indexing operation, overload the

Code Patterns for subsref and subsasgn Methods