The subclassing Singleton was not a requirement, but more of a curiosity. I am learning Design
Patterns and having a hard time co-relating how these patterns help in a real time development scenario.
So, I wanted to exhaust all the options, pros and cons of using a pattern.
Also, if a Singleton can't be subclassed, can a Singleton class be a subclass of another class/implement an interface? Like multiple Singletons implementing a single interface and a client can choose which singleton instance he wants. Again this is a 'Can this be done?' question.