CODESAMPLE

Lazy Initialization - C#

Lazy Initialization C_sharp

The Lazy Initialization pattern delays the creation of an expensive object until its first use (when its value is actually needed). This improves performance, especially if the object is not always required. C# provides the Lazy<T> type to easily implement this pattern. The example below demonstrates creating a Singleton instance only when Instance is first accessed. This ensures the potentially costly Singleton constructor is not called unnecessarily. The ThreadSafe option makes the instance creation thread-safe, which is typical for singletons. The use of a property with a get accessor that uses Lazy<T>.Value is the standard and efficient way to expose the lazily initialized instance in C#.

using System;

public class Singleton
{
    private Singleton() { } // Private constructor to prevent external instantiation

    public static readonly Lazy<Singleton> Instance =
        new Lazy<Singleton>(() => new Singleton(), true);

    public string Value { get; set; } = "Singleton Initial Value";
}

public class Example
{
    public static void Main(string[] args)
    {
        // Singleton is not created yet
        Console.WriteLine("Before access: Singleton not created.");

        // Accessing Instance triggers the Singleton's creation
        Singleton s = Singleton.Instance;
        Console.WriteLine("After access: Singleton created.");
        Console.WriteLine(s.Value);

        // Accessing again doesn't recreate the instance
        Console.WriteLine(Singleton.Instance.Value);
    }
}