matlab.mixin.indexing.ForbidsPublicDotMethodCall Class

Namespace: matlab.mixin.indexing

Disallow calling public methods using dot notation

Since R2021b

Description

Classes that inherit from matlab.mixin.indexing.RedefinesParen or matlab.mixin.indexing.RedefinesBrace allow method calls using dot notation. To make such a class mirror the behavior of built-in numeric classes, which disallow method calls with dot, use the matlab.mixin.indexing.ForbidsPublicDotMethodCall superclass. For example, obj is an instance of a class that inherits from RedefinesParen and ForbidsPublicDotMethodCall. The class defines a public method myMethod:

• myMethod(obj) calls the method.

• obj.myMethod errors.

• label="myMethod"; obj.(label) errors.

• obj(1).myMethod calls parenReference.

• label="myMethod"; obj(1).(label) calls parenReference.

ForbidsPublicDotMethodCall cannot be used with classes that inherit from matlab.mixin.indexing.RedefinesDot or matlab.mixin.indexing.OverridesPublicDotMethodCall.

Class Attributes

Abstract	true
HandleCompatible	true

For information on class attributes, see Class Attributes.

Examples

Disallow Dot Method Calls in ArrayWithLabelNoDotMethod

The ArrayWithLabelNoDotMethod class inherits from RedefinesParen and ForbidsPublicDotMethodCall. (To see a full explanation of the ArrayWithLabel class without the use of ForbidsPublicDotMethodCall, see matlab.mixin.indexing.RedefinesParen.)

The ArrayWithLabelNoDotMethod class has two properties: ContainedArray and Label. The ArrayWithLabelNoDotMethod class customizes parentheses indexing into ContainedArray by inheriting from matlab.mixin.indexing.RedefinesParen and implementing all of its abstract methods.

ArrayWithLabelNoDotMethod also provides two public methods:

• value — Displays the indexed values of ContainedArray

• sum — Calculates the sum of the indexed values of ContainedArray

classdef ArrayWithLabelNoDotMethod < ...
    matlab.mixin.indexing.RedefinesParen & ...
    matlab.mixin.indexing.ForbidsPublicDotMethodCall

    properties (Access=private)
        ContainedArray
    end
    
    properties (Access=public)
        Label
    end
    
    methods
        function obj = ArrayWithLabelNoDotMethod(val)
            obj.ContainedArray = val;
        end
    end

    methods (Access=protected)
        function varargout = parenReference(obj,indexOp)
            obj.ContainedArray = obj.ContainedArray.(indexOp(1));
            if isscalar(indexOp)
                varargout{1} = obj;
                return;
            end
            % Syntax for forwarding indexing operations
            [varargout{1:nargout}] = obj.(indexOp(2:end));
        end

        function obj = parenAssign(obj,indexOp,varargin)
            if isscalar(indexOp)
                assert(nargin==3);
                rhs = varargin{1};
                obj.ContainedArray.(indexOp) = rhs.ContainedArray;
                return;
            end
            [obj.(indexOp(2:end))] = varargin{:};
        end

        function n = parenListLength(obj,indexOp,ctx)
            if numel(indexOp) <= 2
                n = 1;
                return;
            end
            containedObj = obj.(indexOp(1:2));
            n = listLength(containedObj,indexOp(3:end),ctx);
        end

        function obj = parenDelete(obj,indexOp)
            obj.ContainedArray.(indexOp) = [];
        end
    end

    methods (Access=public)
        function out = value(obj)
            out = obj.ContainedArray;
        end
        
        function out = sum(obj)
            out = sum(obj.ContainedArray,"all");
        end
        
        function out = cat(dim,varargin)
            numCatArrays = nargin-1;
            newArgs = cell(numCatArrays,1);
            for ix = 1:numCatArrays
                if isa(varargin{ix},'ArrayWithLabel')
                    newArgs{ix} = varargin{ix}.ContainedArray;
                else
                    newArgs{ix} = varargin{ix};
                end
            end
            out = ArrayWithLabel(cat(dim,newArgs{:}));
        end

        function varargout = size(obj,varargin)
            [varargout{1:nargout}] = size(obj.ContainedArray,varargin{:});
        end
    end

    methods (Static, Access=public)
        function obj = empty()
            obj = ArrayWithLabel([]);
        end
    end
end

Construct an ArrayWithLabelNoDotMethod object with a 2-by-2 matrix, and assign a string to the Label property.

a = ArrayWithLabelNoDotMethod([2 3; 5 7]);
a.Label = "primes"

a = 

  2×2 ArrayWithLabelNoDotMethod array with properties:

    Label: "primes"

Display the array using the value method. Call value without using dot notation.

value(a)

ans = 

     2     3
     5     7

Make the same method call using dot notation. Because this class inherits from ForbidsPublicDotMethodCall, MATLAB^® errors.

a.value

Dot method call is not supported for objects of type 'ArrayWithLabelNoDotMethod'.
Consider using function call syntax.

Version History

Introduced in R2021b