Table of Contents
When would you use the Gang of Four Decorator design pattern?
Decorator pattern is one of the widely used structural patterns. This pattern dynamically changes the functionality of an object at runtime without impacting the existing functionality of the objects.
Which of the following Gang of Four GOF design patterns is associated with the creation of objects?
Creational Design Patterns Allows the creation of objects without specifying their concrete type. Builder. Uses to create complex objects. Factory Method.
Which statement best describes the Gang of Four design patterns?
Which statements best describe the Gang of Four design patterns called Memento and Observer? Memento notifies multiple classes of changes. Observer captures and restores an object’s internal state. Memento defers the exact steps of an algorithm to a subclass.
What are Scala design patterns?
Design pattern is a general reusable solution to a commonly occurring problem in software design. A design pattern is not a finished code, but rather a template for how to solve a problem that can be used in many different situations.
How does the decorator pattern work?
Decorator patterns allow a user to add new functionality to an existing object without altering its structure. The decorator design pattern is a structural pattern, which provides a wrapper to the existing class. Decorator design pattern uses abstract classes or interfaces with the composition to implement the wrapper.
What are the benefits of design patterns implementation?
Design patterns help promote easier program changes and object reusability. Loosely coupled objects are easier to reuse and change. Keeping objects small and specialized promotes loose coupling. Design patterns are built with many small specialized objects.
What is factory pattern in Scala?
The factory method is used to offer a single interface to instantiate one of the multiple classes. In the Factory pattern, the objective is to make the object in such a way that it does not expose to the creation logic to the Client and can always refer to a newly created object with the help of a common interface.
What is Scala take?
In Scala Stack class , the take() method is utilized to return a stack consisting of the first ‘n’ elements of the stack. Method Definition: def take(n: Int): Stack[A] Return Type: It returns a stack consisting of the first ‘n’ elements of the stack.
Where are Decorator patterns used?
A Decorator pattern can be used to attach additional responsibilities to an object either statically or dynamically. A Decorator provides an enhanced interface to the original object.
What is the Gang of Four design patterns?
Gang of Four Design Patterns Over 20 years ago the iconic computer science book “ Design Patterns: Elements of Reusable Object-Oriented Software ” was first published. The four authors of the book: Erich Gamma, Richard Helm, Ralph Johnson, and John Vlissides, have since been dubbed “The Gang of Four”.
What are the classical design patterns in Scala?
The classical design patterns are the 23 design patterns by GoF. This project implements dozens of design patterns in Scala. The Scala language has several advanced features which make the implementations are different from other programming languages. Design patterns are categorized into:
Who initiated the concept of design pattern in software development?
The gang of four, authors Erich Gamma, Richard Helm, Ralph Johnson and John Vlissides, initiated the concept of Design Pattern in Software development. These authors are collectively known as Gang of Four (GOF).
Is the GoF design patterns book relevant to Java programming?
Even though the GoF Design Patterns book was published over 20 years ago, it still continues to be an Amazon best seller. The GoF wrote the book in a C++ context but it still remains very relevant to Java programming. C++ and Java are both object-oriented languages.