Documentation

Object Precedence

Establishing an object precedence enables MATLAB^® to determine which of possibly many versions of an operator or function to call in a given situation.

For example, consider the expression

objectA + objectB

Ordinarily, objects have equal precedence and the method associated with the leftmost object is called. However, there are two exceptions:

Consider the example in Representing Polynomials with Classes. The DocPolynom class defines a plus method that enables the addition of DocPolynom objects. Given the object p:

p = DocPolynom([1 0 -2 -5])
p =
    x^3-2*x-5

the expression:

1 + p
ans =
    x^3-2*x-4

calls the DocPolynom plus method (which converts the double, 1, to a DocPolynom object and then implements the addition of two polynomials). The DocPolynom class has precedence over the built-in double class.

Defining Precedence

You can specify the relative precedence of classes defined with the classdef syntax by listing inferior classes in a class attribute. The InferiorClasses property places a class below other classes in the precedence hierarchy. Define the InferiorClasses property in the classdef statement:

classdef (InferiorClasses = {?class1,?class2}) myClass

This attribute establishes a relative priority of the class being defined with the order of the classes listed.

objectA + objectB