assignin 'caller' fails when variable is a matlab function in the path

I wrote this handy function to parse 'key', value pairs in function calls with using varargin. The function goes as follows:

function setdefvarargin(in,varargin)

% assign default 'param' value pairs in the calling workspace
% 
% input param value pairs are assigned to variables in the calling
% workspace. default values passed in pairs as varargin are assigned if not
% provided as input.

innames = in(1:2:end);
for i = 1:2:numel(varargin)
    idx = regexpcell(innames,varargin{i});% (see fileexchange)
    if not(isempty(idx))
        assignin('caller',varargin{i}, in{2*idx});
    else
        assignin('caller',varargin{i}, varargin{i+1});
    end
end

%%%%%%%%%%%%% I call this function at the beginning of another one to define default values for 'key' value pairs. For instance, in a function like this:

function test(data,varargin)

setdefvarargin(varargin,'key1',1,'key2','default','key3',[])
% so that default values are assigned to key1, key2 and key3
% if they are not provided as key-value pairs in varargin
key1
key2
key3

Now the problem arises if any key has the name of a function in the path. I tried for instance with

setdefvarargin(varargin,'event',[],'type','fix','transform',[],'isfact',[]);

Because type is a matlab function, when later in the code, I have

switch type
    case 'fix'
        % some commands
    case 'rand'
        % some other commands
end

I get the following error.

Error using type
Too many output arguments.

I fixed the issue by entering

type = [];

before the setdefvarargin line but it's not really clean...

Any comment here is welcome. Thanks.

Answer 1

[Matt J]

It's a well-known problem with assignin and other functions that create variables non-explicitly. That's why creating variables inexplicitly using assigin, eval, load, etc... is always discouraged. I recommend the attached file instead.

I also recommend you consider this FEX tool

http://www.mathworks.com/matlabcentral/fileexchange/26216-structure-fields-to-variables

for unpacking the structures created with the attached file into separate variables, if that's what you prefer to do.