使用 C# 泛型扩展方法对 class 而不是集合进行操作

Question

I have the following types defined:
-----------------------------------

interface IMyInterface<T> where T : class
{
   void BlahBlah();
}
abstract class MyBase<T> : IMyInterface<T> where T : class
{
   public abstract T MyInfo { get; set; }
   public abstract T MyInfo2 { get; set; }
   public void BlahBlah()
   {
       Console.WriteLine(MyInfo + ", " + MyInfo2);
   }
}
class MyConcreteClass1<T> : MyBase<T> where T : class
{
   public override T MyInfo { get; set; }
   public override T MyInfo2 { get; set; }
}
class MyConcreteClass2<T> : MyBase<T> where T : class
{
   public override T MyInfo { get; set; }
   public override T MyInfo2 { get; set; }
}


public static class DataOperations<T, U> where T : class where U : class
{
        public static U Operate(this T source, U destination)
        {
            var sourceProps = source.GetType().GetProperties();
            var destinationProps = destination.GetType().GetProperties();

                .
                .
                .
            return destination;
        }
}

我想做的是在实现中对上述两个 classes 进行操作：

MyConcreteClass1<String> class1 = new MyConcreteClass1<String>();
class1.MyInfo = "Some Value";
class1.MyInfo2 = "another value";
MyConcreteClass2<String> class2 = new MyConcreteClass2<String>();
var c2 = class1.Operate(class2);

问题是我得到： "CS1106 Extension method must be defined in a non-generic static class" DataOperations class 名称。

Answer 1

声明类型必须是非泛型，但方法可以是泛型。改为考虑：

public static class DataOperations
{
        public static U Operate<T, U>(this T source, U destination)
             where T : class where U : class
        { // ...
        }
}

Answer 2

将通用定义移动到方法上：

public static class DataOperations
{
        public static U Operate<T, U>(this T source, U destination)  where T : class where U : class
        {
            // Whatever
        }
}

Answer 3

必须在 非通用 静态（顶级）class.

中定义扩展方法 - 作为错误状态

因此您需要将 DataOperations class 设为非泛型，并将方法本身改为泛型：

public static class DataOperations
{
        public static U Operate<T, U>(this T source, U destination) where T : class where U : class

        {
            var sourceProps = source.GetType().GetProperties();
            var destinationProps = destination.GetType().GetProperties();

                .
                .
                .
            return destination;
        }
}

使用 C# 泛型扩展方法对 class 而不是集合进行操作

using c# generics extension methods to operate on a class and not a collection

c#

linq

generics

extension-methods