C# 通用和覆盖方法

Question

I created a question and realized that it was due to some design error on my part. However, I do think that that concept can be useful and I would like to know how to solve an issue similar, if possible.

I want to create an algorithm that adds up 2 numbers, be it string or int . I also want to be able to output everything in the console and would like to avoid code duplication. I create a generic interface that changes according to the model. Then a class that handles the addition of the two members. Note that the data comes from the handler classes (which in real life scenario, get information to fill model from external data).

Please note that I do know that I know there are much simpler ways of doping this, but I want to understand why it does not work. Now, the code does not compile in the ValidateHandler<T>(IAddHandler<T> handler) due to cannot convert from 'T' to 'Test.Models.StringModel' . Why cannot it select the right overridden method? I tried adding generics to the overridden method, but it still does not work. How can I make ValidateHandler<T> select the right method from it's type?

Here is the code I wrote.

Models:

public class IntegerModel
{
    public int A { get; set; }

    public int B { get; set; }

    public int C { get; set; }
}

public class StringModel
{
    public string A { get; set; }

    public string B { get; set; }

    public string C { get; set; }
}

Interface:

public interface IAddHandler<T>
{
    T Add();

    void GetData();
}

Handlers:

public class IntegerHandler : IAddHandler<IntegerModel>
{
    public IntegerModel IntegerModel { get; set; }

    public void GetData()
    {
        // Get Info to Add from external file for example
        IntegerModel = new IntegerModel { A = 10, B = 20 };
    }

    public IntegerModel Add()
    {
        IntegerModel.C = IntegerModel.A + IntegerModel.B;

        return IntegerModel;
    }
 }

public class StringHandler : IAddHandler<StringModel>
{
    public StringModel StringModel { get; set; }

    public void GetData()
    {
        // Get Info to Add from external file for example
        StringModel = new StringModel { A = "10", B = "20" };
    }

    public StringModel Add()
    {
        StringModel.C = StringModel.A + StringModel.B;
        return StringModel;
    }
 }

Here is the Main with it's function

public static void Main(string[] args)
{
    var integerHandler = new IntegerHandler();
    var stringHandler = new StringHandler();

    ValidateHandler(integerHandler);
    ValidateHandler(stringHandler);
}

public static void ValidateHandler<T>(IAddHandler<T> handler)
{
    handler.GetData();
    var result = handler.Add();

    WriteResults(result);
}

public static void WriteResults(StringModel model)
{
    Console.WriteLine(model.C);
}

public static void WriteResults(IntegerModel model)
{
    Console.WriteLine(model.C);
}

I know I can do the following, but it seems ineffective in doing so and I do not see the point of using generics then.

public static void ValidateHandler<T>(IAddHandler<T> handler)
{
    handler.GetData();
    var result = handler.Add();

    if (typeof(T) == typeof(StringModel))
    {
        WriteResults(result as StringModel);
    }
    else if (typeof(T) == typeof(IntegerModel))
    {
        WriteResults(result as IntegerModel);
    }
}

Answer 1

I'd write a non-generic IModel interface which uses object instead of the type parameter, and implement it explicitly in your generic class.