Question

I’m writing a method that do a cast and I need receive an type as parameter, for example:

object foo(?? type, object input) { 

    if(type is x ) { 
       Output output = new Output();
       x xValue = (x) input; 
       foreach(var val xValue) { 
          //do.. 
       }

       return output; 
    }

    if(type is y) {
          Output2 output = new Output2();
          y yValue = (y) input; 

        foreach(var val yValue) { 
          //do.. 
        }

       return output;
    } else { 
      //invalid type
    }
}

Answer 1

Use a type parameter:

object foo<T>(T input) {
  if (T is x) { ...
  ...

Also, your method is a little weird, there seems to be a lot of commonality in your branches, and testing for types is not normally a good approach. Make an effort to unify them or split the method in type-specific overloads:

Output foo(x input) ...

Output2 foo(y input) ...

...

And, try to use a more specific return type, as shown above.