使用功能 <T,TResult> C＃

Question

I am working on PCL which along with a lot of functionality also provides log in. Also I recently started using delegates.

The Current Case:

I have a Simple methods that takes in parameters and provide GPlus, Facebook or Simple logIn with Username and Password. as in the code below:

public async Task<SignInResponse> SignInUsingFacebook(IFacebookInitializer faceBookConfiguration)
{
   //my code
}
public async Task<SignInResponse> SignInUserNameAndPass(string username,string password)
{
   //my code
}
public async Task<SignInResponse> SignInUsingGPlus(IGPlusInitializer gPlusConfiguration)
{
   //my code
}

This is great, I can call them from my application directly and handle data but, I recently came across Delegates and Func<T,TResult>

What I want to do:

I want a simple method that takes in a parameter an enum of LogInType as below:

public enum LogInType
{
    UserNameAndPassword,
    Facebook,
    GooglePlus,
}

and based on the type of login type provided to the method, handles the LogIn process on it's own and just returns the SignInResponse object.

---

Is there a way this can be done using Delegates. Rather than having 3 individual methods to call for each case. If yes, then can someone please help in the parameters to be passed to the Single method along with The LogInType. I know it has to be a Func but what would the Func look like as it has to take 3 different parameters.

---

As From the Comments:

Each of those methods is a different signature anyway so you have a Func<IFacebookInitializer , Task<SignInResponse>> , Func<string, string, Task<SignInResponse>> and Func<IGPlusInitializer, Task<SignInResponse>> so you'd still end up with an if statement.

Can I return a Func when the method is called? this ways I can return either of the three func based on a quick switch case. The issue would be (if it's possible) what would be the generic response (or the common response) type of the method that returns either of these three methods

Answer 1

The generic Func works as follows: The last datatype that you define in Func - "output" in this case should be the return type of the method which you are going to that particular function and the method should also be static. This might help:

Func<LogInType, string> Login = LoginMethod;

private static string LoginMethod(LogInType loginType)
{
    if (loginType == LogInType.Facebook)
        return "Facebook";
    if (loginType == LogInType.GooglePlus)
        return "GooglePlus";
    if (loginType == LogInType.UserNameAndPassword)
        return "UserNameAndPassword";
    return "Default";
}

The return type in the above example is string just for explaining.