Methods That Modify Default Behavior

How to Customize Class Behavior

There are functions that MATLAB^® calls implicitly when you perform certain actions with objects. For example, a statement like [B(1);A(3)] involves indexed reference and vertical concatenation.

You can change how user-defined objects behave by defining methods that control specific behaviors. To change a behavior, implement the appropriate method with the name and signature of the MATLAB function.

Which Methods Control Which Behaviors

The following table lists the methods to implement for your class and describes the behaviors that they control.

Class Method to Implement	Description
Concatenating Objects
`cat`, `horzcat`, and `vertcat`	Customize behavior when concatenating objects See Subclasses of Built-In Types with Properties
Creating Empty Arrays
`empty`	Create empty arrays of the specified class. See Empty Arrays
Displaying Objects
`disp` `display`	Called when you enter `disp(obj)` on the command line Called by statements that are not terminated by semicolons. `disp` is often used to implement `display` methods. See Overloading the disp Function See Custom Display Interface
Converting Objects to Other Classes
converters like `double` and `char`	Convert an object to a MATLAB built-in class See The Character Converter and The Double Converter
Indexing Objects
`subsref` and `subsasgn`	Enables you to create nonstandard indexed reference and indexed assignment See Object Array Indexing
`end`	Supports `end` syntax in indexing expressions using an object; e.g., `A(1:end)` See end as Object Index
`numel`	Determine the number of elements in an array See Modify nargout and nargin for Indexing Methods
`numArgumentsFromSubscript`	Overload to specify the number of values to return from indexing expressions. See Number of Arguments for subsref and subsasgn
`size`	Determine the dimensions of an array See Use of size and numel with Classes
`subsindex`	Support using an object in indexing expressions See Objects in Index Expressions
Saving and Loading Objects
`loadobj` and `saveobj`	Customize behavior when loading and saving objects See Object Save and Load
Reshape and Rearrange
`permute`	Rearrange dimensions of N-D array
`transpose`	Transpose vector or matrix
`ctranspose`	Complex conjugate transpose
`reshape`	Reshape array
`repmat`	Replicate array along specified dimensions
Determine Size and Shape
`isscalar`	Determine if the input is a scalar
`isvector`	Determine if the input is a vector
`ismatrix`	Determine if the input is a matrix
`isempty`	Determine if the input is empty

Overload Functions and Override Methods

Overloading and overriding are terms that describe techniques for customizing class behavior. Here is how we use these terms in MATLAB.

Overloading

Overloading means that there is more than one function or method having the same name within the same scope. MATLAB dispatches to a particular function or method based on the dominant argument. For example, the timeseries class overloads the MATLAB plot function. When you call plot with a timeseries object as an input argument, MATLAB calls the timeseries class method named plot.

To call the nonoverloaded function, use the builtin function.

Overriding

Overriding means redefining a method inherited from a superclass. MATLAB dispatches to the most specific version of the method. That is, if the dominant argument is an object of the subclass, then MATLAB calls the subclass method.

To control class dominance, use the InferiorClasses attribute.

Documentation