C#•4mo ago

Enum based Singleton

This is the description for my job training task:

Implement the Singleton class using the Enum approach to create a thread-safe Singleton instance without the need for lazy initialization or explicit locking.

Write a program to demonstrate that the Singleton instance is created only once and accessed safely by multiple threads using the Enum approach.

Implement the Singleton class using the Enum approach to create a thread-safe Singleton instance without the need for lazy initialization or explicit locking.

Write a program to demonstrate that the Singleton instance is created only once and accessed safely by multiple threads using the Enum approach.

I don't understand how to implement this. I find myself coding the same old implementation with a static backing field. Not here to get my homework done. I'm genuinely trying to learn

8 Replies

SleepWellPupper•4mo ago

What is "the Enum approach"? Also, a solution to singleton without lazy or locking is to simply instantiate eagerly a static field/property and hide the constructor of your class.

Anton•4mo ago

they probably mean constants wrapped in a class static constructors are thread safe afaik so yeah, that's probably the anwer

canton7•4mo ago

I assume that's referring to something earlier in the training material?

textYashOP•4mo ago

That's what I don't understand... I kinda have no one to ask what's to be done oh okay its actually a thing. I found java implementations online:

public enum SingletonEnum {
    INSTANCE;

    int value;

    public int getValue() {
        return value;
    }

    public void setValue(int value) {
        this.value = value;
    }
}

public enum SingletonEnum {
    INSTANCE;

    int value;

    public int getValue() {
        return value;
    }

    public void setValue(int value) {
        this.value = value;
    }
}

canton7•4mo ago

Java enums are very different to C# enums You can't do that in C#

textYashOP•4mo ago

yea exactly im unable to find any ACTUAL implementation I found this C# based on on a website:

public enum ProductEnum
{
  INSTANCE
}
public static class ProductEnumExtensions
{
  private static int state = 0;
  public static void DoSomething(this ProductEnum it) {
    System.Console.WriteLine("I did something for the {0} time", ++state);
  }
}

public enum ProductEnum
{
  INSTANCE
}
public static class ProductEnumExtensions
{
  private static int state = 0;
  public static void DoSomething(this ProductEnum it) {
    System.Console.WriteLine("I did something for the {0} time", ++state);
  }
}

but I don't think the enum plays any role here

canton7•4mo ago

Yes, someone copied some Java docs, and didn't update them for C#

SleepWellPupper•4mo ago

Well java enum singletons seem to be simple static readonly fields/props that are initialized eagerly to their value.

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Enum based Singleton