How to combine argument validation with varargin

How can I make varargin work in conjunction with an arguments block? In the function below, the first two inputs W and p have very specific validation criteria. However, I have additional arguments, which I am trying to capture with varargin, with no validation criteria that I would like to enforce at this point.

someFunc(5,1,'dog',{2},6)  


function someFunc(W,p, varargin)
     arguments
         W {mustBeNumeric}
         p int8 {mustBeScalarOrEmpty,mustbeInteger}=2
         varargin 

Function argument definition error in someFunc. varargin can only be used inside Repeating arguments block.

     end
     
     W,p, varargin
             
end

As shown, the call throws an error saying that varargin can only be used inside Repeating arguments blocks, but I can find no relevant documentation or examples on that. Removing varargin from the arguments block altogether also generates an error:

File: test.m Line: 5 Column: 24

Function argument definition error in someFunc. Arguments block and function line must contain the same arguments in the

same order, including ignored arguments.

Is there simply no way to use varargin and arguments in conjunction?

Answer 1

[Paul]

My understanding from reading Avoid Using varargin for Repeating Arguments is that putting varargin into a Repeating arguments block without any restrictions would allow the code to work.

someFunc(5,1,'dog',{2},6)  

W = 5

p = int8 1

varargin = 1×3 cell array
    {'dog'}    {1×1 cell}    {[6]}

vargin elements are:

ans = 'dog'

ans = 1×1 cell array
    {[2]}

ans = 6

function someFunc(W,p, varargin)
     arguments
         W {mustBeNumeric}
         p int8 {mustBeScalarOrEmpty,mustBeInteger}=2
     end
     arguments (Repeating)
         varargin
     end
     W,p, varargin
     disp('vargin elements are:')
     for ii = 1:numel(varargin)
         varargin{ii}
     end
             
end

[Matt J]

Excellent!

Answer 2

[Matt J]

This is one solution, but is very inconvenient, because it requires that I offload the argument checking to another function, checkIt(). Were I allowed to nest the checkIt function within someFunc, it wouldn't be so bad, but arguments blocks can't be used in nested functions (as of R2021b).

someFunc(5,1,'dog',{2},6)  

W = 5

p = int8 1

varargin = 1×3 cell array
    {'dog'}    {1×1 cell}    {[6]}

function someFunc(W,p, varargin)

    [W,p] = checkIt(W,p);

    W,p, varargin

end


function [W,p] = checkIt(W,p)
  arguments
     W {mustBeNumeric}
     p int8 {mustBeScalarOrEmpty,mustBeInteger}=2
  end
end