将对象转换为方法泛型类型

问题描述

这会产生一个错误，提示我无法转换类型 ClassType 到 T .有什么解决方法吗?

This generates an error saying I cannot convert type ClassType to T. Is there any workaround for this?

有没有办法指定实际上可以将 this 的类型转换为 T 的类型?

Is there any way to specify that the type of this can in fact be converted to T?

public void WorkWith<T>(Action<T> method)
{
    method.Invoke((T)this);
}

推荐答案

两种可能的解决方案:

不是类型安全的:

public void WorkWith<T>(Action<T> method)
{
    method.Invoke((T)(object)this);
}

这不是类型安全的，因为您可以将具有单个参数且没有返回值的任何方法传递给它，例如:

This isn't typesafe because you can pass it any method that has a single parameter and no return value, like:

WorkWith((string x) => Console.WriteLine(x));

类型安全的版本"(使用通用约束):

The typesafe "version" (using generic constraints):

public class MyClass
{
    public void WorkWith<T>(Action<T> method) where T : MyClass
    {
        method.Invoke((T)this);
    }
}

这里的要点是为了能够将 this 强制转换为 T ，编译器希望确保 this 始终可转换为 T (因此需要约束).如非类型安全的示例所示，与泛型一起使用的经典"(不安全)解决方案正在通过类型转换传递给 object .

The point here is that to be able to cast this to T, the compiler wants to be sure that this is always castable to T (so the need for the constraint). As shown in the not-type-safe example, the "classical" (unsafe) solution used with generics is passing through a cast to object.

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