MATLAB Object-Oriented Programming

NoteThe AllowedSubclasses and the InferiorClasses attributes require an

explicit specification of a cell array of meta.class objects as their values. You cannot

use expressions to return these values.

See “Attribute Specification” on page 5-22 for more information on attribute syntax.

Expressions That Specify Default Property Values

Property definitions allow you to specify default values for properties using any

expression that has no reference to variables. For example, VectorAngle defines a

constant property (Rad2Deg) and uses it in an expression that defines the default value of

another property (Angle). The default value expression also uses a static method

(getAngle) defined by the class:

classdef VectorAngle

properties (Constant)

Rad2Deg = 180/pi

end

properties

Angle = VectorAngle.Rad2Deg*VectorAngle.getAngle([1 0],[0 1])

end

methods

function obj = VectorAngle(vx,vy)

obj.Angle = VectorAngle.getAngle(vx,vy);

end

end

methods (Static)

function r = getAngle(vx,vy)

% Calculate angle between 2D vectors

cr = vx(1)*vy(1) + vx(2)*vy(2)/sqrt(vx(1)^2 + vx(2)^2) * ...

sqrt(vy(1)^2 + vy(2)^2);

r = acos(cr);

end

end

end

You cannot use the input variables to the constructor to define the default value of the

Angle property. For example, this definition for the Angle property is not valid:

properties

Angle = VectorAngle.Rad2Deg*VectorAngle.getAngle(vx,vy)

end

6 Defining and Organizing Classes