C#:IEnumerable,GetEnumerator,一个简单,简单的例子,请!
试图创建一个实现get枚举器的uebersimple类,但由于缺少简单/无function的例子而疯狂失败。 我想要做的就是在数据结构周围创建一个包装器(在这种情况下是一个列表,但我以后可能需要一个字典)并添加一些函数。
public class Album { public readonly string Artist; public readonly string Title; public Album(string artist, string title) { Artist = artist; Title = title; } } public class AlbumList { private List Albums = new List; public Count { get { return Albums.Count; } } ..... //Somehow GetEnumerator here to return Album }
谢谢!
您只需返回List
public class AlbumList : IEnumerable { // ... public IEnumerator GetEnumerator() { return this.albums.GetEnumerator(); } IEnumerator IEnumerable.GetEnumerator() { return GetEnumerator(); } }
除了其他答案之外,如果您需要更多地控制枚举器的工作方式,或者是否需要在基础数据结构提供的范围之外进行自定义,那么您可以使用yield
关键字。
public class AlbumList : IEnumerable { public IEnumerator GetEnumerator() { foreach (Album item in internalStorage) { // You could use conditional checks or other statements here for a higher // degree of control regarding what the enumerator returns. yield return item; } } }
using System.Collections; using System.Collections.Generic; public class AlbumList : IEnumerable { private List Albums = new List (); public int Count { get { return Albums.Count; } } public IEnumerator GetEnumerator() { return this.Albums.GetEnumerator(); } IEnumerator IEnumerable.GetEnumerator() { return this.GetEnumerator(); } }
或简化版本:
public class AlbumList { private List Albums = new List (); public int Count { get { return Albums.Count; } } public IEnumerator GetEnumerator() { return this.Albums.GetEnumerator(); } }
我不建议省略IEnumerable
接口,因为你松散了与.NET的集成,例如使用LINQ的可能性,但你可以使用C#中的foreach
迭代集合。
或者这个甚至更短:-)
public class AlbumList : List { }
当然,最后一个是可变列表,可能并不完全是你想要的。
根据你想要在数据结构(列表)周围有一个包装器的注释,以及一个返回一个Album的枚举器函数,我认为你在谈论索引器属性,对吧? 这是你如何做到的:
public class Album { public readonly string Artist; public readonly string Title; public Album(string artist, string title) { Artist = artist; Title = title; } } public class AlbumList { private List Albums = new List (); public int Count { get { return Albums.Count; } } public Album this[int index] { get { return Albums[index]; } } public Album this[string albumName] { get { return Albums.FirstOrDefault(c => c.Title == albumName); } } public void Add(Album album) { Albums.Add(album); } public void Remove(Album album) { Albums.Remove(album); } }
一个小的控制台程序:
AlbumList albums = new AlbumList(); albums.Add(new Album { Artist = "artist1", Title = "title1" }); albums.Add(new Album { Artist = "artist2", Title = "title2" }); for (int i = 0; i < albums.Count; i++) { Console.WriteLine(albums[i].Artist); Console.WriteLine(albums[i].Title); } Console.WriteLine("title for artist1"); Console.WriteLine(albums["artist1"].Title);