mustBeA

Validate that value comes from one of specified classes

Syntax

mustBeA(value,classNames)

Description

mustBeA(value,classNames) compares value with a list of class names in classNames and throws an error if the class of value is not one of the named classes or a subclass of one of the named classes. This function does not return a value.

Class support: All MATLAB^® classes

Examples

Determine if Value Is of Specific Type

Validate that a value is a scalar or an array of type string or uint8.

a = 'red';
mustBeA(a,["string","uint8"])

Value must be of the following types: 'string' or 'uint8'.

Passing a character vector is not valid because mustBeA restricts text values to strings only.

b = [1 0 0];
mustBeA(b,["string","uint8"])

Value must be of the following types: 'string' or 'uint8'.

Passing an array of double integers is not valid because mustBeA restricts numeric values to uint8 only.

Valid Subclass

Subclasses satisfy the "isa" relationship with superclasses. Therefore, a value that is a subclass of one of the specified classes is valid.

Define a subclass of uint8.

classdef ColorSpec < uint8
    methods
        function obj = ColorSpec(c)
            if nargin == 0
                c = uint8(0);
            end
            obj = obj@uint8(c);
        end
    end
end

Create an object of the ColorSpec class.

a = ColorSpec([1 0 0])

a = 

  1×3 ColorSpec:

  uint8 data:
   1   0   0

The ColorSpec object contains uint8 data.

Test the validity of the ColorSpec object with mustBeA. The following statement does not produce an error.

mustBeA(a,["string","uint8"])

Input Arguments

value — Value to validate

scalar | array

Value to validate, specified as a scalar or an array of any MATLAB or user-defined type.

classNames — Name of one or more classes

string array | character vector | cell array of character vectors

Names of one or more classes, specified as a string array, character vector, or cell array of character vectors.

Example: ["double", "single"]

Tips

• mustBeA is designed to be used for property and function argument validation.

Extended Capabilities

C/C++ Code Generation

Generate C and C++ code using MATLAB® Coder™.

Usage notes and limitations::

• Code generation does not support string arrays. To pass names of two or more classes to mustBeA, use a cell array of character vectors.

Thread-Based Environment
Run code in the background using MATLAB® backgroundPool or accelerate code with Parallel Computing Toolbox™ ThreadPool.

Version History

Introduced in R2020b