c# - 在由以下内容组成的对象上向 List 添加新方法

Question

有没有办法在 List 对象的基础上向 List 对象添加新方法。换句话说，类是否可以这样编写，当 List 由它构成时，它会向该 List 添加新方法。这是一个例子:

class Employee
{
    public int age;
    public Employee(int age)
    {
         this.age = age;
    }
    //some more code here...
}

然后:

List<Employee> sector01 = new List<Employee>(){new Employee(22), new Employee(35)};
sector01.OutputAll(); //Adds method like this

Answer 1

您可以将其定义为 extension method :

namespace SomeNamespace
{
    public static class ListExtensions
    {
        public static void OutputAll(this IEnumerable<Employee> employees)
        {
            foreach (var employee in employees)
            {
                Console.WriteLine("{0}: {1}", employee.FirstName, employee.LastName);
            }
        }
    }
}

然后简单地将定义这个静态类的命名空间引入作用域:

using SomeNamespace;

现在您将能够做到这一点:

List<Employee> sector01 = new List<Employee>()
{
    new Employee(22), 
    new Employee(35)
};
sector01.OutputAll();