How to avoid “too many parameters” problem in API design?

Question

I have this API function:

public ResultEnum DoSomeAction(string a, string b, DateTime c, OtherEnum d, 
     string e, string f, out Guid code)

Answer 1

One style embraced in the frameworks is usually like grouping related parameters into related classes (but yet again problematic with mutability):

var request = new HttpWebRequest(a, b);
var service = new RestService(request, c, d, e);
var client = new RestClient(service, f, g);
var resource = client.RequestRestResource(); // O params after 3 objects