Which are C# native built-in design patterns?

Question

Which design patterns are build-in supported by C# regardless framework version? I'm thinking of patterns such as Observer pattern that can be found in interface IObservable. ObservableCollection, INotifyPropertyChanged etc.

Please provide with the namespace of the pattern in your answers!

Answer 1

Action<T> (normally used as visitor pattern)

Discover the Design Patterns You're Already Using in the .NET Framework (MSDN Magazine)

Example

public class Root {     //Private and not exposed in a IList property = Encapsulation     private List<Node> _nodes = new List<Node>();       public void Accept(Action<Node> visitor)     {         // Controlled enumeration, can for instance handle exceptions in here.         foreach (var item in _nodes)         {             visitor(node);         }     } }  // usage root.Accept(node => Console.WriteLine(node)); 

Answer 2

Creational Patterns

Abstract Factory

• System.Data.Common.DbProviderFactory

Builder

• System.Text.StringBuilder
• System.Data.Common.DbConnectionStringBuilder

Factory Method

• System.Activator
• System.Net.WebRequest

Prototype

• System.ICloneable

Singleton

• System.StringComparer.InvariantCulture
• System.StringComparer.InvariantCultureIgnoreCase

Structural Patterns

Adapter

• System.IO.StreamReader

Bridge

• System.Globalization.CultureInfo

Composite

• System.ComponentModel.IComponent

Decorator

• System.IO.Stream

Facade

• System.Environment
• System.String

Flyweight

• System.StringComparer

Proxy

• System.Net.WebClient
• System.Runtime.Remoting.Proxies.RealProxy
• System.ServiceModel.ICommunicationObject

Behavioral Patterns

Chain Of Responsibility

• Microsoft.Practices.EnterpriseLibrary.Logging.Logger

Command

• System.Windows.RoutedEventArgs

Interpreter

• System.IFormatProvider
• System.Text.RegularExpressions.Regex

Iterator

• System.Collections.IEnumerable
• System.Data.IDataReader

Mediator

• System.Threading.Timer

Memento

• System.Runtime.Serialization.ISerializable

Observer

• System.EventHandler
• System.IObservable

State

• ??

Strategy

• System.Collections.Generic.IComparer

Template Method

• System.Web.UI.Page

Visitor

• System.Linq.Expressions.ExpressionVisitor