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Class: matlab.System

Set whether System object input size can change


mutable = isInputSizeMutableImpl(obj,index)


mutable = isInputSizeMutableImpl(obj,index) returns whether the indexth input to the object can change size when the object is in use.

Method Authoring Tips

You must set Access = protected for this method.

Input Arguments

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System object handle used to access properties, states, and methods specific to the object. If your isInputSizeMutableImpl method does not use the object, you can replace this input with ~.

This argument specifies which input to stepImpl is checked for size mutability. The index number is the ordinal position of the input in the stepImpl signature.

Output Arguments

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If you do not implement this method, inputs can change size unless the StrictDefaults class attribute is set. If you implement this method, returning true means that input size can change, and false means they cannot change.


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Restrict the size of all inputs by adding the isInputSizeMutableImpl method and returning false. By adding this method, users of the System object cannot change the size of inputs while the System object is in use.

function flag = isInputSizeMutableImpl(obj,~)
    flag = false;

To avoid a warning about unused variables, this example uses ~ as the second input argument. For more information about using ~ in place of arguments, see Using ~ as an Input Argument in Method Definitions.

This example shows how to write the isInputSizeMutableImpl method to only restrict the first input. isInputSizeMutableImpl returns true for all inputs except input the first input.

methods (Access = protected)
    function flag = isInputSizeMutableImpl(obj,index)
        flag = (index ~= 1);
Introduced in R2018a