Simple Matlab utility to test and return the relative precedence of the given arguments. Inspired by Matt J's answer to the Matlab Answers question "How can I determine if one class is superior or inferior to another?" (http://www.mathworks.com/matlabcentral/answers/89208)

argPrecedence.m

function [priority,classes] = argPrecedence(varargin)
% argPrecedence Return the relative class priority of the arguments
% 
% Returns an array the same size as the argument list with each argument's
% relative priority level, with 1 as the highest.
% 
% Optionally returns a second output of class names, with the unique classes 
% of the argument list arranged in priority order.
% 
% Note that the priority is dependent both on argument position and class.

priority = nan(size(varargin));
classes = cellfun(@class,varargin,'un',false);

args = varargin;
arg_idxs = 1:numel(args);
arg_classes = classes;
p = 1;

while ~isempty(args)
    try
        undefined_function_____(args{:})
    catch ME
        assert(strcmp(ME.identifier,'MATLAB:UndefinedFunction'))
        C = textscan(ME.message,'%s','delimiter','''');
        superior_class = C{1}{4}; % Dependent on locale, probably.
        
        mask = strcmp(arg_classes,superior_class);
        assert(any(mask),'The error message does not have a class of an argument')
        
        priority(arg_idxs(mask)) = p;
        p = p + 1;
        
        args(mask) = [];
        arg_idxs(mask) = [];
        arg_classes(mask) = [];
        continue
    end
    error('function should always error')
end

assert(~any(isnan(priority)),'Some arguments were not assigned a priority.')

if nargout > 1
    % Return class names in priority order
    [~,idxs] = sort(priority);
    classes = unique(classes(idxs),'stable');
end