How to deal with name/value pairs of function arguments in MATLAB

Question

I have a function that takes optional arguments as name/value pairs.

function example(varargin)
% Lots of set up stuff
vargs = varargin;
nargs = length(vargs         


        

Answer 1

I ended up writing this today, and then found these mentions. Mine uses struct's and struct 'overlays' for options. It essentially mirrors the functionality of setstructfields() except that new parameters can not be added. It also has an option for recursing, whereas setstructfields() does it automatically. It can take in a cell array of paired values by calling struct(args{:}).

% Overlay default fields with input fields
% Good for option management
% Arguments
%   $opts - Default options
%   $optsIn - Input options
%       Can be struct(), cell of {name, value, ...}, or empty []
%   $recurseStructs - Applies optOverlay to any existing structs, given new
%   value is a struct too and both are 1x1 structs
% Output
%   $opts - Outputs with optsIn values overlayed
function [opts] = optOverlay(opts, optsIn, recurseStructs)
    if nargin < 3
        recurseStructs = false;
    end
    isValid = @(o) isstruct(o) && length(o) == 1;
    assert(isValid(opts), 'Existing options cannot be cell array');
    assert(isValid(optsIn), 'Input options cannot be cell array');
    if ~isempty(optsIn)
        if iscell(optsIn)
            optsIn = struct(optsIn{:});
        end
        assert(isstruct(optsIn));
        fields = fieldnames(optsIn);
        for i = 1:length(fields)
            field = fields{i};
            assert(isfield(opts, field), 'Field does not exist: %s', field);
            newValue = optsIn.(field);
            % Apply recursion
            if recurseStructs
                curValue = opts.(field);
                % Both values must be proper option structs
                if isValid(curValue) && isValid(newValue) 
                    newValue = optOverlay(curValue, newValue, true);
                end
            end
            opts.(field) = newValue;
        end
    end
end

I'd say that using the naming convention 'defaults' and 'new' would probably be better :P