matlab.mixin.Heterogeneous.getDefaultScalarElement

Class: matlab.mixin.Heterogeneous
Namespace: matlab.mixin

Return default object for heterogeneous array operations

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Syntax

defaultObject = getDefaultScalarElement

Description

defaultObject = getDefaultScalarElement returns the default object for a heterogeneous hierarchy. The implementation of getDefaultScalarElement inherited from the matlab.mixin.Heterogeneous class returns an instance of the root class. The root class is the direct subclass of matlab.mixin.Heterogeneous in a heterogeneous hierarchy.

If the root class is abstract or is not an appropriate default object for the classes in the heterogeneous hierarchy, you must override getDefaultScalarElement in the root class to return a default object. getDefaultScalarElement must return a scalar instance of another member of the heterogeneous hierarchy.

MATLAB® calls the getDefaultScalarElement method to fill in gaps in a heterogeneous array. For more information, see Defining the Default Object.

Output Arguments

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The default object for a heterogeneous hierarchy.

Attributes

Statictrue
Accessprotected

To learn about attributes of methods, see Method Attributes.

Examples

This example describes a heterogeneous hierarchy with a root class (FinancialObjects) that is an abstract class and therefore cannot be used for the default object.

Heterogeneous array hierarchy

The FinancialObjects class definition includes an override of the getDefaultScalarElement method, which returns an instance of the Assets class as the default object.

classdef FinancialObjects < matlab.mixin.Heterogeneous
   methods (Abstract)
      val = determineCurrentValue(obj)
   end
   methods (Static,Sealed,Access=protected)
      function default_object = getDefaultScalarElement
         default_object = Assets;
      end
   end
end

Tips

  • Override getDefaultScalarElement only if the root class is not suitable as a default object.

  • Override getDefaultScalarElement only in the root class of the heterogeneous hierarchy.

  • getDefaultScalarElement must return a scalar object.

  • getDefaultScalarElement must be a static method with protected access. While not required by MATLAB, you can seal this method to prevent overriding by other classes.

  • MATLAB returns an error if the value returned by getDefaultScalarElement is not scalar or is not an instance of a class that is a valid member of the hierarchy.

Version History

Introduced in R2011b

See Also