What is the Proxy Pattern? The definition of the Proxy Pattern from both Design Patterns: Elements of Reusable Object-Oriented Software and Head First Design Patterns: A Brain-Friendly Guide is The Proxy Pattern provides a surrogate or placeholder for another object to control access to it. Proxy Pattern Class Diagram Explained The above class diagram represents … [Read more…]
What is the State Pattern? The definition of the State Pattern from both Design Patterns: Elements of Reusable Object-Oriented Software and Head First Design Patterns: A Brain-Friendly Guide is The State Pattern allows an object to alter its behavior when its internal state changes. The object will appear to change its class. State Pattern Class … [Read more…]
What is the Adapter Pattern? The definition of the Adapter Pattern from both Design Patterns: Elements of Reusable Object-Oriented Software and Head First Design Patterns: A Brain-Friendly Guide is The Adapter Pattern converts the interface of a class into another interface clients expect. Adapter lets classes work together that couldn’t otherwise because of incompatible interfaces. … [Read more…]
What is the Singleton Pattern? The Singleton Pattern makes sure a class has only one instance and provides a way to access it globally. It’s typically preferred, within the development community, to find alternatives to using global access, if possible. What the Singleton Pattern does better than say, a global variable, is that it’s access … [Read more…]
What is the Abstract Factory Pattern? In a previous post, I described the Factory Method Pattern and provided a C++ code example. In this post I would like to provide information on another factory pattern, the Abstract Factory Pattern. Let’s jump right in and start with the Abstract Factory Pattern’s formal definition from “Head First … [Read more…]
What is the Factory Method Pattern? If you are looking for a way to encapsulate the creation of objects, factory patterns are just what you need. There are multiple factory patterns but in this post I will just be focusing on the Factory Method Pattern. It is a factory pattern so we should expect the … [Read more…]
What is the Decorator Pattern? Ever find yourself creating derived classes to add new or variant behavior from an existing class? I have. It seems like a good idea to start but can quickly become a complex maintenance nightmare. I have learned my lesson and avoid falling into that mindset when I need to add … [Read more…]
What is the Observer Pattern? The Observer Pattern is a design pattern that allows any number of objects to observe state of a single object and be informed of any changes. The single object is typically described as the subject where the objects interested in changes of the subject are known as observers. The observers … [Read more…]
One of the design patterns I have used often in my career is the Strategy Pattern. This is a very powerful pattern. I like the definition from my favorite patterns book, “Head First Design Patterns: A Brain-Friendly Guide“ The Strategy Pattern defines a family of algorithms, encapsulates each one, and makes them interchangeable. Strategy lets … [Read more…]
The Private Implementation Design Pattern (PImpl) is a nice way to hide the internals of a class from other classes that would depend on it otherwise. The advantage of doing so is that it simplifies the header dependency tree which will result in faster build times. For larger systems and/or slow build servers, this may … [Read more…]