argument suggestion with shared argument validator

Hello matlab community.

I am facing a problem with function argument validation and auto-completion. I have a set of static methods which share the same argument validation. In the following example, the input argument must belong to ["a", "b"].

I cannot find a way to have a common definition of this vector membership without losing auto completion:

classdef dummyClass

    properties (Constant)
        m = ["a", "b"];
    end

    methods (Static)
        
        % this method works but membership vector is hardcoded
        function s = fun1(a)
            arguments
                a {mustBeMember(a,["a", "b"])} = "a"
            end
            s = a;
        end
        
        % using a third party validator does not trigger auto completion
        function s = fun2(a)
            arguments
                a {mustBeAorB(a)} = "a"
            end
            s = a;
        end
        
        % yield an error as dummyClass.m is not defined
        function s = fun3(a)
            arguments
                a {mustBeMember(a,dummyClass.m)} = "a"
            end
            s = a;
        end

        function mustBeAorB(a)
            arguments
                a {mustBeMember(a,["a", "b"])} = "a"
            end
        end
    end
end

There is apparently a solution using json file, but I would like to avoid it if possible.

Do you have any suggestion ?

Answer 1

[Sugandhi]

Hi,

I understand that you are facing a problem with function argument validation and auto-completion.

The possible work around could be, to define the valid membership vector as a class constant instead of a property constant. This way, you can reference the vector using the class name in instances where the auto-completion is lost.

Here's an updated version of your code that implements this approach:

classdef dummyClass    
    methods (Static)        
        % Define valid membership vector as a class constant        
        function m = validMembership()            
            m = ["a", "b"];            
        end  
        
        % Use validMembership class constant to validate input argument in the mustBeMember constraint        
        function s = fun3(a)            
            arguments                
                a {mustBeMember(a,dummyClass.validMembership())} = "a"                
            end            
            s = a;            
        end        
    end    
end

In the code above, the valid membership vector is now defined as a class constant within a static function called 'validMembership'. 'The mustBeMember' constraint used in `fun3` references this class constant by calling `dummyClass.validMembership()`.

This approach provides a common definition for the valid membership vector without hard coding the values or relying on a third-party validator. It also retains auto-completion in the function when typing `dummyClass.`.

[guillaume deguyon]

Hi, thank you for your answer.

Using the membership function as you suggest, I get a similar error than if I use a constant property:

It won't accept anything that is not literal or previously defined arguments.

I tried it on both matlab 2022b and 2023a.

I also came to this json solution for code suggestion, but it adds maintenance workload and does not solve the problem of having a unique definition of the membership vector

Answer 2

[VBBV]

function s = fun3(a)
          arguments
              a {mustBeMember(a,@dummyClass)} = "a"
          end
          s = a;
end

Did you try calling the dummyClass as above ?

[guillaume deguyon]

I tried. But I get the same error: it only accepts previously declared arguments or literals.

I also tried to define it via a non static method, so the class object is an argument of the function. But it refuses to access a property of the object: