Build a static delegate from non-static method

Question

I need to create a delegate to a non-static method of a class. The complications is that at the time of creation I don\'t have an intance to the class, only its class defini

Answer 1

You have two options, you can treat it like you would an extension method. Create an delegate to take in the object and any optional arguments and pass those arguments to the actual function call. Or create one using Delegate.CreateInstance as Dan mentioned.

e.g.,

string s = "foobar";

// "extension method" approach
Func substring1 = (s, startIndex) => s.Substring(startIndex);
substring1(s, 1); // "oobar"

// using Delegate.CreateDelegate
var stype = typeof(string);
var mi = stype.GetMethod("Substring", new[] { typeof(int) });
var substring2 = (Func)Delegate.CreateDelegate(typeof(Func), mi);
substring2(s, 2); // "obar"

// it isn't even necessary to obtain the MethodInfo, the overload will determine
// the appropriate method from the delegate type and name (as done in example 2).
var substring3 = (Func)Delegate.CreateDelegate(typeof(Func), s, "Substring");
substring3(3); // "bar"

// for a static method
var compare = (Func)Delegate.CreateDelegate(typeof(Func), typeof(string), "Compare");
compare(s, "zoobar"); // -1