Question

Using reflection on a method definition I would like to find out if the original method was defined with ‘params’ on the last parameter. So can I discover if the original definition was this…

public void MyMethod(int x, params object[] args); 

…and not this…

public void MyMethod(int x, object[] args); 

My code has a list of arguments and is using reflection to call an arbitrary method. If it is marked with ‘params’ then I want to package up the extra parameters into an object[] and call the method. If the argument is not marked with ‘params’ then I would indicate an error instead. So I want to provide the same semantics as C#.

But I cannot find any docs that indicate how to discover this using reflection.

Answer 1

Use ParamArrayAttribute attribute

class Program {     public void MethodWithParams(object param1, params int[] param2)      {                 }      static void Main(string[] args)     {         var method = typeof(Program).GetMethod('MethodWithParams');         var @params = method.GetParameters();         foreach (var param in @params)          {             Console.WriteLine(param.IsDefined(typeof(ParamArrayAttribute), false));         }     } }