Singleton Pattern Versus Static Class

The Singleton pattern, unlike a keyword, is a well-known design pattern employed in software development. It offers several distinct advantages over static classes. The Singleton pattern facilitates the creation of a solitary, persistent instance of a class throughout the lifespan of an application. This singular instance can be treated as a regular object, passed as a parameter to other methods, and interacted with accordingly. In contrast, a static class solely permits static methods and precludes the ability to pass it as a parameter.

Singleton Pattern VS. Static Class

A Singleton implementation affords the ability to implement interfaces, inherit from other classes, and support inheritance itself. In contrast, a static class cannot inherit instance members and lacks such flexibility. Consequently, Singleton exhibits a higher degree of versatility when compared to static classes and enables the maintenance of state.

Furthermore, a Singleton can be initialized lazily or asynchronously and can be loaded automatically by the .NET Framework's CLR (common language runtime) upon the loading of the program or namespace that encompasses the class. Conversely, a static class is typically initialized during its initial loading, potentially giving rise to class loader issues.

By adhering to the principles of object-oriented programming, Singleton classes allow for polymorphic handling, enabling their users to interact with singletons without imposing assumptions about the existence of only one instance. On the contrary, static classes lack such polymorphic capabilities.

1. Singleton Objects stored on heap while static class stored in stack.
2. Singleton Objects can have constructor while Static Class cannot.
3. Singleton Objects can dispose but not static class.
4. Singleton Objects can clone but not with static class.

Conclusion

In short, single means single object across the application life cycle, so the scope is at application level. The static does not have any Object pointer, so the scope is at App Domain level. Moreover both should be implemented to be thread-safe.