Question

I have a generic function static Log<T>(T Log). I would like to check type of T and decide what to do next.

This is what I got so far:

public static void Log<T>(T log)
{
    switch (typeof(log))
    { ... }
}

What am I doing wrong? My error is that typeof(log) doesnt work.

Answer 1

switch (expression)
{

}

expression = An integral or string type expression (From MSDN)

http://msdn.microsoft.com/en-us/library/06tc147t(v=vs.71).aspx

The typeof keyword returns neither of these. You can’t use log.GetType() as you need to meet the criteria above of which Type isn’t suitable.

To be on the safe side I would limit this to if statements with the corresponding types as this will achieve the same thing.

static void a<T>(T b)
{
  if (typeof(T) == typeof(B))
    Console.WriteLine("T is B");
  else if(typeof(T) == typeof(C))
    Console.WriteLine("T is C");
}

EDIT:

If you have for arguments sake you have:

  public class Vehicle 
  {
    public virtual int MoveVehicle() 
    {
       //Do Logic
       return 0;
    }
  }
  public class Car : Vehicle { }

And you want a generic method to move the Vehicle you could do something called generic type constraints

static void a<T>(T b) where T : Vehicle
{
    int newPosition = b.MoveVehicle();
}

http://msdn.microsoft.com/en-us/library/bb384067.aspx

T has to be a Vehicle now, so you have access to the methods in Vehicle. You can pass a car to the method and it will still be able to call the MoveVehicle method.

  a<Vehicle>(new Car());