In software engineering, Creational Design Patterns deal with object creation mechanisms, trying to create objects in a manner suitable to the situation. The basic or ordinary form of object creation could result in design problems or added complexity to the design. In this article of the Creational Design Patterns, we’re going to take a look at the much-hated & commonly asked design pattern in a programming interview. That is Singleton Design Pattern in Modern C++ which criticizes for its extensibility and testability. I will also cover the Multiton Design Pattern which quite contrary to Singleton.

The code snippets you see throughout this series of articles are simplified and unsophisticated. So you often see me not using keywords like override, final, public(while inheritance) just to make code compact & consumable(most of the time) in single standard screen size. I also prefer struct instead of class just to save line by not writing “public:” sometimes and also miss virtual destructor, constructor, copy constructor, prefix std::, deleting dynamic memory, intentionally. I also consider myself a pragmatic person who wants to convey an idea in the simplest way possible rather than the standard way or using Jargons.

Note:

• If you stumbled here directly, then I would suggest you go through, “What Is Design Pattern?” first, even if it is trivial. I believe it will encourage you to explore more on this topic.
• All of this code you encounter in this series of articles are compiled using C++20(though I have used Modern C++ features up to C++17 in most cases). So if you don’t have access to the latest compiler you can use https://wandbox.org/ which has preinstalled boost library as well.

Intent

To create one & only one instance of a class at any point in time.

The Singleton Design Pattern ensures that a class has only one instance and provides a global point of access to that instance. This is useful when exactly one object need to coordinate actions across the system. So, essentially, the Singleton Design Pattern is nothing more than specifying a lifetime.

#design patterns #c++ #cplusplus #programming-c