Question

Okay, so I realised after writing some overloaded methods that webmethods can’t be overloaded (by realised I mean VS threw a paddy and wouldn’t allow me to update the service references). I have tried to get around that like this:

    public string DoPing<T>(T IP)
    {

        if (typeof(T) == typeof(string))
        { 
            return DoPingString(IP);
        }
        if (typeof(T) == typeof(IPAddress))
        {
            return DoPingIP(IP);
        }
        throw new Exception("Programmer Error");
    }

But I’m getting a cannot convert from T to string/Ipadress error when I call the respective (renamed) methods.
Can someone explain why it doesn’t work, and possibly either fix it or give me an alternate solution?
Thanks in advance.

Edit: Good point, generics are probably overkill (I tried for another solution and failed before trying this).
DoPingString(string String) and DoPingIP(IPAdress Address) are the signatures.
I will give the tick to the closest answer tomorrow. I solved the problem in a separate way.

Answer 1

You’re not using generics the way it was intended. The compiler has no idea what type T is, so it won’t just let you implicitly or explicitly cast to String or IPAddress.
Here’s a version that works:

    public string DoPing<T>(T IP)
    {
        if (typeof(T) == typeof(string))
        {
            return DoPingString((String)Convert.ChangeType(IP, typeof(String)));
        }
        if (typeof(T) == typeof(IPAddress))
        {
            return DoPingIP((IPAddress)Convert.ChangeType(IP, typeof(IPAddress)));
        }
        throw new Exception("Programmer Error");
    }

However, since you’re using generics with no constraint, you gain no benefit from the generic implementation. Why not just take an object?

public string DoPing(Object IP)
{
    if (IP.GetType() == typeof(string))
    {
        return DoPingString((String)IP);
    }
    if (IP.GetType() == typeof(IPAddress))
    {
        return DoPingIP((IPAddress)IP);
    }
    throw new Exception("Programmer Error");
}

Of course, the simpler and easier approach would be to simply overload your function, i.e.:

public string DoPing(string IP)
{
    return DoPingString(IP);
}
public string DoPing(IPAddress IP)
{
    return DoPingIP(IP);
}