Handle Input Specification Changes - MATLAB & Simulink (original) (raw)

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This example shows how to control the input specifications for a System object™. You can control what happens when an input specification changes.

You can also restrict whether the input complexity, data type, or size can change while the object is in use. Whichever aspects you restrict cannot change until after the user calls release.

React to Input Specification Changes

To modify the System object algorithm or properties when the input changes size, data type, or complexity, implement the processInputSpecificationChangeImpl method. Specify actions to take when the input specification changes between calls to the System object.

In this example, processInputSpecificationChangeImpl changes theisComplex property when either input is complex.

properties(Access = private) isComplex (1,1) logical = false; end

methods (Access = protected) function processInputSpecificationChangeImpl(obj,input1,input2) if(isreal(input1) && isreal(input2)) obj.isComplex = false; else obj.isComplex = true; end end end

Restrict Input Specification Changes

To specify that the input complexity, data type, and size cannot change while the System object is in use, implement the isInputComplexityMutableImpl, isInputDataTypeMutableImpl, and isInputSizeMutableImpl methods to return false. If you want to restrict only some aspects of the System object input, you can include only one or two of these methods.

methods (Access = protected) function flag = isInputComplexityMutableImpl(,) flag = false; end function flag = isInputDataTypeMutableImpl(,) flag = false; end function flag = isInputSizeMutableImpl(,) flag = false; end end

Complete Class Definition File

This Counter System object restricts all three aspects of the input specification.

classdef Counter < matlab.System %Counter Count values above a threshold

properties
    Threshold = 1
end

properties (DiscreteState)
    Count
end

methods
    function obj = Counter(varargin)
        setProperties(obj,nargin,varargin{:});
    end
end

methods (Access=protected)
    function resetImpl(obj)
        obj.Count = 0;
    end
    
    function y = stepImpl(obj, u1)
        if (any(u1 >= obj.Threshold))
            obj.Count = obj.Count + 1;
        end
        y = obj.Count;
    end
    
    function flag = isInputComplexityMutableImpl(~,~)
        flag = false;
    end
    
    function flag = isInputDataTypeMutableImpl(~,~)
        flag = false;
    end
    
    function flag = isInputSizeMutableImpl(~,~)
        flag = false;
    end
end

end

See Also

isInputSizeMutableImpl

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