C 11 new feature: static abstract members in interfaces

Before

Suppose we have a very complicated mathematical operation ：

public static int Calc(int x, int y) => x + y;

however , The above method can only support int type . If you need to pass in other numeric types , Need to define again ：

public static double Calc(double x, double y) => x + y;

For this need , We prefer to adopt a paradigm approach to realize ：

public static T Calc<T>(T x, T y) => x + y;

however , Operator “+” Cannot be applied to “T” and “T” Operands of type ：

C# 11

quote System.Runtime.Experimental NuGet package , And add... To the project file <EnablePreviewFeatures>True</EnablePreviewFeatures>.

Define the following method ：

public static T Calc<T>(T x, T y) where  T : INumber<T> => x + y;

Now? , No matter what data type is passed , Can be executed normally ：

Calc(4, 5);
Calc(4.0, 5.0);

This is because , We use System.Runtime.Experimental Define the number type ,int、double All inherited INumber Interface ：

and INumber The interface inherits IAdditionOperators Interface , The operator is defined “+”:

public interface IAdditionOperators<TSelf, TOther, TResult> where TSelf : IAdditionOperators<TSelf, TOther, TResult>
{
    public static abstract TResult operator +(TSelf left, TOther right);
}

Here we use C# 11 New features available , You can add static abstract members to the interface .

The main scenario for this functionality is the use of mathematical operators in generic types , Because operators must be defined as statically abstract ：

besides , You can also define other static members and static attributes in the interface ：

public interface IDemo
{
    public static abstract string StaticProperty { get; set; }
}

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