[C #] delegation and method group

When writing delegation-related code, especially generic delegation-related code, you may encounter the following problem: Define a delegation type: [csharp] public delegate void TestDelegate <T> (T arg); defines a test class and Method: [csharp] public class TestClass {public void TestFunc4Delegate (int arg) {} public void TestFunc1 (Delegate dele) {} public void TestFunc2 <T> (TestDelegate <T> dele) {}} code used for testing: [csharp] 1. testClass tc = new TestClass (); 2. tc. testFunc1 (tc. testFunc4Delegate); 3. tc. testFunc2 (tc. testFunc4Del Egate); then, you will find that the code used in the above test has a compilation error. The compilation error in the second row is "The method group cannot be converted to System. delegate ". The third line of compilation error is" TestClass cannot be exported from usage. testFunc2 <T> (TestDelegate <T>) type parameter ". The core issue for the above errors is the "method group. "Method group" is a compiler concept. Because C # supports method overloading, methods with the same name may have multiple implementation methods for overloading, all the methods with the same names are combined into a method group. In the above example, tc. TestFunc4Delegate actually points to the method group named Test4Delegate. Although the class definition above does not overload Test4Delegate, it is still a method group. Since it is a method group, the problem arises-you cannot determine which overload of the method group is required. The compiler cannot determine which delegate subtype to use to create a delegate instance because it cannot be determined, and the correct type of the generic type cannot be deduced. To enable the call in the preceding example to be compiled, you must specify a qualified type, as shown in the following figure: [csharp] tc. testFunc1 (TestDelegate <int>) tc. testFunc4Delegate); tc. testFunc2 <int> (tc. test4Delegate );