C# and its optional parameters - a language feature..
Optional parameters is a language feature, the compiler is responsible for translating the calls to methods with optional parameters to full call with values.
Look at this simple piece of code below,</span>
When you disassemble these methods, you will see that the C# compiler actually replaced the call to TestMethod with one parameter to a call with both the parameters.
The implication is that methods utilizing optional parameters cannot be bound at run time. The below line of code will not compile because, the line is trying to utilize default value set in optional second parameter of the TestMethod. However, because this bound only during the run time, compiler will not have any control to pass the default values like in the screen shot. Hence this is currently limited by the compiler.
Func<int, bool> func = TestMethod;
The work around is to simply bind the func to an anonymous method which can have the call to TestMethod in its body. Like below,
Func<int, bool> func = (value) => TestMethod(value);