Customize Display of Scalar Objects

Objective

Customize the display of scalar objects.

Design of Custom Display

Note

This example uses the EmployeeInfo class described in the Class with Default Object Display section.

The objective of this customized display is to:

  • Modify the header to include the department name obtained from the Department property

  • Group properties into two categories titled Public Info and Personal Info.

  • Modify which properties are displayed

  • Modify the values displayed for Personal Info category

  • Use the default displayed for nonscalar objects, including empty arrays, and scalar deleted handles

For example, here is the customized display of an object of the EmployeeInfo class.

Emp123 = 

EmployeeInfo Dept: Product Development

   Public Info
        Name: 'Bill Tork'
    JobTitle: 'Software Engineer'

   Personal Info
      Salary: 'Level: 10'
    Password: '*******'

Implementation

The EmployeeInfo class overrides two matlab.mixin.CustomDisplay methods to implement the display shown:

displayScalarObject Method Override

MATLAB® calls displayScalarObject to display scalar objects. The EmployeeInfo class overrides this method to implement the scalar display. Once overridden, this method must control all aspects of scalar object display, including creating the header, property groups, and footer, if used.

This implementation:

  • Builds a custom header using the getClassNameForHeader static method to return linked class name text and the value of the Department property to get the department name.

  • Uses sprintf to add a new line to the header text

  • Displays the header with the built-in disp function.

  • Calls the getPropertyGroups override to define the property groups (see following section).

  • Displays the property groups using the displayPropertyGroups static method.

Here is the EmployeeInfo override of the displayScalarObject method. The required protected access is inherited from the superclass.

methods (Access = protected)
   function displayScalarObject(obj)
      className = matlab.mixin.CustomDisplay.getClassNameForHeader(obj);
      scalarHeader = [className,' Dept: ',obj.Department];
      header = sprintf('%s\n',scalarHeader);
      disp(header)
      propgroup = getPropertyGroups(obj);
      matlab.mixin.CustomDisplay.displayPropertyGroups(obj,propgroup)
   end
end

getPropertyGroups Override

MATLAB calls getPropertyGroups when displaying scalar or nonscalar objects. However, MATLAB does not call this method when displaying a scalar handle to a deleted object.

The EmployeeInfo class overrides this method to implement the property groups for scalar object display.

This implementation calls the superclass getPropertyGroups method if the input is not scalar. If the input is scalar, this method:

  • Defines two titles for the two groups

  • Creates a cell array of property names that are included in the first group. MATLAB adds the property values for the display

  • Creates a struct array of property names with associated property values for the second group. Using a struct instead of a cell array enables you to replace the values that are displayed for the Salary and Password properties without changing the personal information stored in the object properties.

  • Constructs two matlab.mixin.util.PropertyGroup objects, which are used by the displayScalarObject method.

Here is the EmployeeInfo override of the getPropertyGroups method. The required protected access is inherited from the superclass.

methods (Access = protected)
   function propgrp = getPropertyGroups(obj)
      if ~isscalar(obj)
         propgrp = getPropertyGroups@matlab.mixin.CustomDisplay(obj);
      else
         gTitle1 = 'Public Info';
         gTitle2 = 'Personal Info';
         propList1 = {'Name','JobTitle'};
         pd(1:length(obj.Password)) = '*';
         level = round(obj.Salary/100);
         propList2 = struct('Salary',...
            ['Level: ',num2str(level)],...
            'Password',pd);
         propgrp(1) = matlab.mixin.util.PropertyGroup(propList1,gTitle1);
         propgrp(2) = matlab.mixin.util.PropertyGroup(propList2,gTitle2);
      end
   end
end

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