Matlab Single Value Default Function

function default(varargin)
   param = [varargin{:} ';'];
   ind = find(param=='=');
   stmt = 'if ~exist(''%s'',''var'');%s;end';
   str = sprintf(stmt,param(1:(ind(1)-1)),[varargin{:}]);
   evalin('caller', str);
end


Example use

default x=2