nargin vs exist

Question

Given a function like:

function foo(myParam)
if nargin<1
  myParam = \'default value\';
end % if
end % function

I\'ve seen people use so

Answer 1

I always validate arguments using nargchk, and then go with the nargin tests as you had them. As others pointed out, they're cheaper, and I think clearer.

In functions that I expect to be re-used heavily, I always put lots of checks up front, and then structure the code to call the real implementation later.

I also tend to structure optional arguments (when not using varargin) like this:

function x = myfcn( arg1, opt_arg2 )
if nargin < 2
   arg2 = 'default';
else
   arg2 = opt_arg2;
end

as I think this makes it more obvious when editing the file which arguments are expected to be optional.