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Singleton Pattern-Creational Patterns

Posted By: Rahul     Posted Date: January 19, 2010    Points: 2   Category :Patten/Practices
The Singleton pattern is a specialist creational pattern as it's primary focus is to facilitate a single shared instance of our object rather than to decouple our client from the object's implementation as with the other creational patterns.

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Prototype Pattern-Creational Patterns in C#

The Prototype Pattern approaches the creation of the objects that our client will use by cloning instances from prototypes as required. This achieves the general aim of decoupling the client from the objects that it will use, but also adds some advantages unique to the Prototype pattern.

Abstract Factory Pattern-Creational Patterns

The Factory pattern allowed us to decouple our client from an object which it uses. The Abstract Factory pattern extends this idea to manage separate families of objects.

A runtime selection, or configuration option, in our client could decide which family of objects is to be used. The Abstract Factory pattern allows us to write generic code to instantiate and use the family objects regardless of which family is chosen at runtime. The pattern also helps us enforce a rule where objects from just the chosen family are used uniformly by the client.

Singleton Design Pattern in C#, Vb.NET

Ensure a class has only one instance and provide a global point of access to it.

Singleton Design Pattern in Asp.net using C#

When we want to make a only one instance of a class and also making sure that there is a global access point to that object then the design pattern we user is called Singleton. The pattern ensures that the class is instantiated only once and that all requests are directed to that one and only object.

GOF Creational Design Patterns with C#

The GOF design patterns help address the following challenges :

design ready to accommodate change & growth

design flexible systems which come ready to handle reconfiguration and run time tailoring

code in manner to facilitate reuse during the development and extension phases ... ie. both external and internal reuse, so that we are rewarded by efficiencies as the project progresses, coming from investments made earlier in the project.

implement change in a way that doesn't overly shorten the system's useful lifespan

Design Patterns - Using the State Pattern in C#

What is the State Pattern?

The State Pattern is a behavioral pattern that can be used to alter the behavior of an object at run time. As the state of an object changes, the functionality of the object can change drastically. This change of behavior is hidden from the Client and the Client interfaces with a wrapper object known as the Context. The State Pattern is a dynamic version of the Strategy Pattern.

Singleton Pattern and Abstract Class


I know what Singleton Pattern means and Abstract class means.

What I wanted to know was how would this apply to real world.

Could anyone give me any good example or simple explanation.

Say I have a simple website, why would I use any of the above if any.

Why would it simplify my architechture.

Thanks in advace. 

Patterns in Practice: The Unit Of Work Pattern And Persistence Ignorance


Jeremy Miller continues his discussion of persistence patterns by reviewing the Unit of Work design pattern and examining the issues around persistence ignorance.

Jeremy Miller

MSDN Magazine June 2009

Patterns: WPF Apps With The Model-View-ViewModel Design Pattern


In this article we explain just how simple it can be to build a WPF application the right way using the MVVM Pattern.

Josh Smith

MSDN Magazine February 2009

Design Patterns: Simplify Distributed System Design Using the Command Pattern, MSMQ, and .NET


Service-oriented architecture is a great framework when you need to perform distributed computing tasks over the Internet. But when you want to perform processing inside your local network, a different solution may provide a better fit. That solution, based on the Command pattern, uses Windows services and Microsoft Message Queuing to implement a queued system that meets your needs better than a service-oriented solution. This article explains how to build it.

Brad King

MSDN Magazine September 2004

Singleton Pattern


earlier today i was readind about singleton pattern

now i m trying to implement in a testing project

which is like -

public class prodcuttable
    private static prodcuttable _instance = new prodcuttable();
    public static prodcuttable Instance()
        return _instance;

    private prodcuttable()

    public DataTable loadtable()
        DataTable dt = new DataTable();
        DataColumn dc = new DataColumn();
        dc.ColumnName = "ID";
        dc.DataType = Type.GetType("System.Int32");

        dc.ColumnName = "Name";
        dc.DataType = Type.GetType("System.String");
        DataRow dr = dt.NewRow();
        dr["ID"] = 1;
        dr["Name"] = "Aftab";

        return dt;
        //throw new NotImplementedException();

but when i m trying to implement in my Default page

binding with gridview

if (!IsPostBack)
            GridView1.DataSource = prodcuttable.Instance();

its giving me error

The type initializer for 'prodcuttable

"Singleton" pattern in WF 4.0


I am trying to do a singleton pattern with WF and AppFabric. I  want just one instance of a workflow running in the cluster.

I have tried a biztalk style: a method (CallService()) that creates the instance, and the same method in other receive activity (CallService()) that do not have the cancreateinstance checked. (I think I could correlate it through the xpath to the action in the soap message, but lets forget about correlating at this step).

My problem is that WF always creates the instance and does not correlate in the second call.

Do you know how to solve it? I would like to priorize the correlation against the creation of the instances. Any other way to do it?

Thanks in advance.

Implementing the Singleton Pattern in C#

The singleton pattern is one of the best-known patterns in software engineering. Essentially, a singleton is a class which only allows a single instance of itself to be created, and usually gives simple access to that instance. Most commonly, singletons don't allow any parameters to be specified when creating the instance - as otherwise a second request for an instance but with a different parameter could be problematic! (If the same instance should be accessed for all requests with the same parameter, the factory pattern is more appropriate.) This article deals only with the situation where no parameters are required. Typically a requirement of singletons is that they are created lazily - i.e. that the instance isn't created until it is first needed.

Singleton Pattern -How to implement in Application_Start() in Global.asax


need to know how we can implement the singleton Pattern in Global.asax file in Application_Start()

Suppose This is my E.g

 public static string Name { get; set; }
    public static string ID { get; set; }

    //singleton pattern implemented ....gud
    private static Employee _emp = new Employee();

    public static Employee EmpInstance()
        return _emp;

    public void Add()
        string sql = "insert into emp_master values('" + ID + "','" + Name + "')";


on my Button Click


        Employee e1 = Employee.EmpInstance();

        Employee.ID = "2";
        Employee.Name = "asdasd";


now somewhere i heard it's best to decalre in Application_Start()

but how i can declare...any hint.





Dialogs and ViewModel - Using Tasks as a Pattern

The ViewModel/MVVM pattern continues to gain popularity, with a blog post showing up every so often, and with tweets and retweets popping up even more often :-). At the same time, there are some interesting topics beyond the core pattern that continue to fuel experimentation. A big one amongst those is how should applications use dialogs when using the view model pattern.

The crux of the problem is the desire to keep the view model independent of UI concerns, and ensure it can be tested in a standalone manner, but that often comes to odds when you want the view model to launch a dialog, and/or do some work after the dialog is closed.

Prototype Design Pattern in C#. Vb.NET

Specify the kind of objects to create using a prototypical instance, and create new objects by copying this prototype
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