Question

C#中：什么是虚拟事件，如何对它们使用

Answer 1

事件可以被标记为通过使用虚拟关键字的虚拟事件。这使派生类通过使用override关键字重写事件行为。重写虚拟事件的事件也可以被密封，它指定为派生类不再虚拟
using System;

class Base
{
public virtual event EventHandler Foo
{
add
{
Console.WriteLine("Base Foo.add called");
}
remove
{
Console.WriteLine("Base Foo.remove called");
}
}
}

class Derived : Base
{
public override event EventHandler Foo
{
add
{
Console.WriteLine("Derived Foo.add called");
}
remove
{
Console.WriteLine("Derived Foo.remove called");
}
}
}

class Test
{
static void Main()
{
Base x = new Derived();

x.Foo += (sender, args) => {};
}
}