C# Design patterns: the Strategy pattern
January 28, 2009
Summary
Multiple classes implement an interface, handling an algorithm in a different way.
Example
Sorting is the clearest working example of the Strategy pattern. In .NET you’ll find it in the IComparer interface alongside Array.Sort/LINQ, see the links section for an article on this on MSDN.
| namespace DesignPatterns | |
| { | |
| public class User | |
| { | |
| public string Name { get; set; } | |
| public int Age { get; set; } | |
| public override string ToString() | |
| { | |
| return string.Format("{0} {1}", Name, Age); | |
| } | |
| } | |
| /// <summary> | |
| /// Compares two users based on name. | |
| /// </summary> | |
| public class NameSorter : IComparer<User> | |
| { | |
| public int Compare(User x, User y) | |
| { | |
| return x.Name.CompareTo(y.Name); | |
| } | |
| } | |
| /// <summary> | |
| /// Compares two Users based on their age. | |
| /// </summary> | |
| public class AgeSorter : IComparer<User> | |
| { | |
| public int Compare(User x, User y) | |
| { | |
| return x.Age.CompareTo(y.Age); | |
| } | |
| } | |
| /// <summary> | |
| /// A simple extension method class for pretty-printing the | |
| /// List<Users> collection. | |
| /// </summary> | |
| public static class ListExtension | |
| { | |
| public static string Print(this List<User> list) | |
| { | |
| StringBuilder builder = new StringBuilder(); | |
| foreach (User user in list) | |
| { | |
| builder.AppendLine(user.ToString()); | |
| } | |
| return builder.ToString(); | |
| } | |
| } | |
| } |
I'm Chris Small, a software engineer living and working in London. This is my tech blog. Find out more via Github, Stackoverflow, Resume