C#, dynamic return type

Question

What I need is a method that can return a type (no object, cause no casting allowed) following a condition. Here is an example:

??? right (string fullStr, int endPosition)
{
 string tmpStr = "";

 tmpStr = fullStr.Substring(endPosition);

 if(tmpStr.Length == 1)
   return tmpStr[0]; //return a char!!
 else
   return tmpStr; //return a string!!
}

I tried generics but I was only able to return the type that was coming in, (if a char came in a char was returned, and if a string came in a string was returned). I tried this:

    public static T right<T>(T stringToCheck, int endPosition)
    {
        if (typeof(T).ToString() == "System.String")
        {
            string fullString = (string)((object)stringToCheck);
            string response = "";

            response = fullString.Substring(endPosition);

            if (response.Length == 1)
            {

                return (T)((object)response[0]);
            }
            else
                return (T)((object)response);
        }

        return stringToCheck;
    }

I can't use typecasting (returning an object), cant use ref params.

Calls to the method have to stay the same:

right(stringOrChar,int) -> returns string or char.

Thank You

Answer 1

I don't think it's theoretically possible. You could use "dynamic" in C# 4, but if you're not there yet, you can't do that.

If it could return either a string or a character, then it has to be an object that both of those descend from, of which "object" is your only choice. And then you'd have to do casts.

C# (3.5 and previous) needs to know what the single return type of the method is so that it can do checking on the calling method. And in fact, in C#4, when you say "dynamic" it actually uses "object" underneath.

You could create a custom class/struct that has both

public class StringOrChar
{
    char charValue;
    string stringValue;
    bool isString;
}

But it's kludgy.

Why do you want to have different return types?

Answer 2

The return type of a function must be typed. As with any other variable or operation, any type that inherits from the specified type is a valid return value (which is why object allows anything as a value).

The logistics of the caller wouldn't make much sense; how would you know whether to type your variable as a char or a string in your example?

Is there a particular reason that you can't return a string in all cases?