C#C
C#•2y ago
Jack

A (hopefully) basic question about singleton instances

Hello,

I don't know why but I am mixing things up in my head today with the singleton pattern. So the basic pattern goes something like this (simplified for brevity):

public Singleton
{
  private static Singleton _instance;

  public static Instance
  {
    if(_instance == null) _instance = new Singleton();
    return _instance;
  }
}


Now, in my head I had it that the private _instance variable should be an instance variable, i.e. not static. But all examples of the singleton pattern that I have found have the private instance being static. So why is this? Is there a problem with it being an instance variable? Is this just to absolutely ensure that there can only be one instance? I don't have any problem with using a private static field but it was in my head that it shouldn't be so I'd like to understand why I thought that and why it is wrong to do so.
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