SOLID & Design Patterns Interview Question #32

What is the Singleton Pattern?

Structural, Creational & Behavioral Patterns Junior Beginner

Quick Interview Answer

The Singleton Pattern ensures that a type has a single shared instance within a defined process or scope and provides access to that instance. Classic implementations manage construction themselves through a static property.

Detailed Explanation

In modern .NET applications, dependency injection lifetime management is usually preferable to hand-written global singletons because dependencies remain explicit and testing is easier.

Code Example

public sealed class AppClock
{
    private static readonly Lazy<AppClock> _instance =
        new(() => new AppClock());

    private AppClock() { }

    public static AppClock Instance => _instance.Value;
}