I am confused when I read this (regarding singleton design pattern):
How do we ensure that a class has only one instance and that the instance is easily accessible? A global variable makes an object accessible, but it doesn't keep you from instantiating multiple objects.
So what is the use of singleton pattern if we can create multiple instances?
Design Patterns - Elements Of Reusable Object Oriented Software (1995) - Gamma, Helm, Johnson, Vl