我的工作与任务特定的.NET plattform，这是precompiled，而不是开源。 对于某些任务，我需要从它继承来继承这个类，但并非如此。我只是想添加一个方法。

I'm working with a task specific .NET plattform, which is precompiled and not OpenSource. For some tasks I need to extend this class, but not by inheriting from it. I simply want to add a method.

起初，我想告诉你一个虚拟的code存在的类：

At first I want to show you a dummycode existing class:

public class Matrix<T> where T : new() {
    ...
    public T values[,];
    ...
}

我想以下列方式扩展这个类：

I want to extend this class in the following way:

public static class MatrixExtension {
    public static T getCalcResult<T>(this Matrix<T> mat) {
        T result = 0;
        ...
        return result;
    }
}

我有这种语法许多谷歌的链接，以便不知道它是否是正确的。编译器告诉我没有错误，但最终这是行不通的。最后我想调用此函数以下列方式：

I've got this syntax from many google links so no idea whether it is correct. The compiler tells me no error, but in the end it doesn't work. In the end I want to call this function in the following way:

Matrix<int> m = new Matrix<int>();
...
int aNumber = m.getCalcResult();

因此​​，任何人有一个想法？谢谢您的帮助！

So anyone got an idea? Thank you for your help!

问候焾

推荐答案

您需要添加同一类型参数约束的扩展方法。

You need to add the same type parameter constraints on the extension method.

这是我尝试在你的例子中最接近重建的编译和运行，没有任何错误：

This is my attempt at the closest reconstruction of your example that compiles and runs, without any error:

public class Matrix<T>  where T : new() {
     public T[,] values;
 }


 public static class MatrixExtension {
     public static T getCalcResult<T>(this Matrix<T> mat)  where T : new() {
         T result = new T();
         return result;
     }
 }

 class Program {
     static void Main(string[] args)  {
        Matrix<int> m = new Matrix<int>();
        int aNumber = m.getCalcResult();
        Console.WriteLine(aNumber); //outputs "0"
 }