Can't configure predifined char arguments in a function

I'm trying to create a function to work with structures, specifically to write information in any field.

I know I could use "structure.fieldA.fielB = data" but for the final application I'm looking for a cleaner code. That's why I'm doing this function.

Its declaration and arguments definition is the next:

function [s] = add2element(s, element, field, data)
    arguments
        s
        element {mustBeInteger} = 1
        field {mustBeText} = 'Points'
        data {mustBeFinite} = 0
    end
    % Here next is the body of the function, not important right now
end

But when I try to call the function the following error raises:

>> example_s = add2element(example_s, 1, 'Points', 5)
Unrecognized function or variable 'mustBeText'.

Error in add2element

I've written the arguments block by looking at the Argument Validation Functions page and I don't understand why I get this error. The following are the tests I've done with no results:

• I've tried with both validations 'mustBeText' and 'mustBeTextScalar'.
• The field 'Points' was written in a variable field_name = 'Points'

Answer 1

[Ameer Hamza]

mustBeText and mustBeTextScalar were both introduced in R2020b; you cannot use them in R2020a. MATLAB does not provide any validation function for text validation in R2020a: https://www.mathworks.com/help/releases/R2020a/matlab/matlab_prog/argument-validation-functions.html. You can define your own validation function

function myValidationFun(x)
    if ~ischar(x)
        error('Not a char.');
    end
end

place it on MATLAB's path and then in your argument list, specify this validation function for field like this

field {myValidationFun} = 'Points'

[Jaime Gonzalez Gomez]

Ok, that explains it

Thanks a lot

[Ameer Hamza]

I am glad to be of help!