Which are C# native built-in design patterns?

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 pro开发者_JAVA技巧vide with the namespace of the pattern in your answers!

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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));

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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

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Iterator is one (all collection classes and arrays can use the foreach statement for iteration).

Another is the observer pattern - pretty much this is what events are. In 4.0 the IObservable and ObservableCollection were added.

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StringBuilder uses the builder design pattern..
And there is the DbDataAdapter class (adapter pattern).
The Null Object pattern is broadly used as well.

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Observer pattern. All our events and delegates are raised through the observer pattern.

Factory pattern. Connection strings and db providers from factory.

Iterator Pattern: Ienumerable, Ienumerators in our foreach statements

Adapter: COM communication. Runtime Callable Wrappers(RCW)

Template: Used in several places esp in ASP.NET classes where you can override to provide new implementation

Proxy: For all our webservice calls. in c# 3.0 we got proxy collections as well.

There could be many more. But these are the ones that came to my mind

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Abstract Factory: System.Data.Common.DbProviderFactory

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The delegation pattern (that's what the delegates and expresssions are for)

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The proxy pattern is used often.