CSharp/C#, How to implement Singleton pattern

Markus Buehle
#1 / 4

How to implement Singleton pattern

I found two ways to implement the singleton pattern.
1)
sealed class Singleton1
{
private Singleton1();
public static readonly Singleton Instance = new Singleton1();
public void MyMethod()
{
//doSomething
}

Quote:

}

2)
sealed class Singleton2
{
static Singleton2();
public void MyMethod()
{
//doSomething
}

Quote:

}

using it looks like
{
Singleton1.Instance.MyMethod();
Singleton2.MyMethod();

Quote:

}

I'm not sure if the second way has the same thread safety as the first one.
Does anybody see a difference (except the calling) between the two way's.
Which is the better one?

tnx for your opinion
Markus

Sat, 16 Oct 2004 17:02:42 GMT

Vyachesla
#2 / 4

How to implement Singleton pattern

In first way you have more control when instance created
or marked to finalization. For example, you can
implement "lazy" construction.

In second way you can't define indexer, becouse C# have no
concept of static indexer.

But, of course, second way is more elegant.

Sat, 16 Oct 2004 17:39:11 GMT

Nicholas Paldino [.NET/C# MVP
#3 / 4

How to implement Singleton pattern

Markus,

This might not be possible with your setup, but you might want to
consider COM+ and a serviced component for what you want to do. Using COM+,
you can create an object pool for your object. By setting the pool minimum
to 1 and the maximum to 1, you can effectively create a singleton. Also,
using COM+, you can manage concurrency (activity and causalities).

Hope this helps.

--
- Nicholas Paldino [.NET MVP]

Quote:

> I found two ways to implement the singleton pattern.
> 1)
> sealed class Singleton1
> {
> private Singleton1();
> public static readonly Singleton Instance = new Singleton1();
> public void MyMethod()
> {
> //doSomething
> }
> }

> 2)
> sealed class Singleton2
> {
> static Singleton2();
> public void MyMethod()
> {
> //doSomething
> }
> }

> using it looks like
> {
> Singleton1.Instance.MyMethod();
> Singleton2.MyMethod();
> }

> I'm not sure if the second way has the same thread safety as the first
one.
> Does anybody see a difference (except the calling) between the two way's.
> Which is the better one?

> tnx for your opinion
> Markus

Sat, 16 Oct 2004 20:26:02 GMT

Willy Denoyette [MVP
#4 / 4

How to implement Singleton pattern

No 1, but you have to make some changes or it won't compile.

sealed class Singleton1{
private Singleton1() {}
public static readonly Singleton1 Instance = new Singleton1();
public void MyMethod()
{
// do something!
}

Quote:

}

Willy.

Quote:

> I found two ways to implement the singleton pattern.
> 1)
> sealed class Singleton1
> {
> private Singleton1();
> public static readonly Singleton Instance = new Singleton1();
> public void MyMethod()
> {
> //doSomething
> }
> }

> 2)
> sealed class Singleton2
> {
> static Singleton2();
> public void MyMethod()
> {
> //doSomething
> }
> }

> using it looks like
> {
> Singleton1.Instance.MyMethod();
> Singleton2.MyMethod();
> }

> I'm not sure if the second way has the same thread safety as the first one.
> Does anybody see a difference (except the calling) between the two way's.
> Which is the better one?

> tnx for your opinion
> Markus

Sat, 16 Oct 2004 22:20:42 GMT