索引器的重载

 1            Company com = new Company();
 2            com.Departments.Add("HR");
 3            com.Departments.Add("Market");
 4            com.Departments.Add("Development");
 5
 6            com.Departments[0].Staffs.Add("Alice");
 7            com.Departments[0].Staffs.Add("Amy");
 8            com.Departments[0].Staffs.Add("Ellen");
 9            com.Departments[2].Staffs.Add("Albert");
10            com.Departments[2].Staffs.Add("Mark");
11            com.Departments[2].Staffs.Add("Kevin");
12            com.Departments[2].Staffs.Add("Neil");
13
14            System.Console.WriteLine(com.Departments[0].Staffs[1].Name);

在循环处理的时候，第14行自然没有什么不好的地方，但如果像14行那样，要直接访问某个部门，用int的索引似乎显得太突兀。

我们优化DepartmentCollection的this索引器，重载this

 1        public Department this[int index]
 2        {
 3            set
 4            {
 5                this.List[index] = value;
 6            }
 7            get
 8            {
 9                return (Department)this.List[index];
10            }
11        }
12
13        public Department this[string name]
14        {
15            get
16            {
17                for (int i = 0; i <= this.List.Count - 1; i++)
18                {
19                    if (((Department)this.List[i]).Name == name)
20                    {
21                        return this[i];
22                    }
23                }
24                return null;
25            }
26
27        }

然后，我们继续优化Department

 1public class Department
 2    {
 3        public StaffCollection Staffs = new StaffCollection();
 4
 5        public Department(string name)
 6        {
 7            Name = name;
 8        }
 9        public readonly string Name;
10
11        public Staff this[int index]
12        {
13            set
14            {
15                Staffs[index] = value;
16            }
17            get
18            {
19                return Staffs[index];
20            }
21        }
22    }

加了第11行的this。

现在的调用代码是

 1            Company com = new Company();
 2            com.Departments.Add("HR");
 3            com.Departments.Add("Market");
 4            com.Departments.Add("Development");
 5
 6            com.Departments[0].Staffs.Add("Alice");
 7            com.Departments[0].Staffs.Add("Amy");
 8            com.Departments[0].Staffs.Add("Ellen");
 9            com.Departments[2].Staffs.Add("Albert");
10            com.Departments[2].Staffs.Add("Mark");
11            com.Departments[2].Staffs.Add("Kevin");
12            com.Departments[2].Staffs.Add("Neil");
13
14            System.Console.WriteLine(com.Departments["Development"][1].Name);

注意第14行，是不是优雅多了啊？