MATLAB Object-Oriented Programming

Object Converters

In this section...

“Why Implement Converters” on page 17-12

“Converters for Package Classes” on page 17-12

“Converters and Subscripted Assignment” on page 17-13

Why Implement Converters

You can convert an object of one class to an object of another class. A converter method

has the same name as the class it converts to, such as char or double. Think of a

converter method as an overloaded constructor method of another class. The converter

takes an instance of its own class and returns an object of a different class.

Converters enable you to:

• Use methods defined for another class


• Ensure that expressions involving objects of mixed class types execute properly


• Control how instances are interpreted in other contexts

Suppose that you define a polynomial class. If you create a double method for the

polynomial class, you can use it to call other functions that require inputs of type

double.

p = polynomial(...);

dp = double(p);

roots(dp)

p is a polynomial object, double is a method of the polynomial class, and roots is a

standard MATLAB function whose input arguments are the coefficients of a polynomial.

Converters for Package Classes

Classes defined in packages can have names that are a dot-separated list of names. The

last name is a class and preceding names are packages. Name the conversion methods

using the package qualifiers in the method names. For example, a conversion method to

convert objects of MyClass to objects of the PkgName.PkgClass class uses this method

name:

17 Specialize Object Behavior