Book Image

Hands-On Design Patterns with C++ (Second Edition) - Second Edition

By : Fedor G. Pikus
5 (1)
Book Image

Hands-On Design Patterns with C++ (Second Edition) - Second Edition

5 (1)
By: Fedor G. Pikus

Overview of this book

C++ is a general-purpose programming language designed for efficiency, performance, and flexibility. Design patterns are commonly accepted solutions to well-recognized design problems. In essence, they are a library of reusable components, only for software architecture, and not for a concrete implementation. This book helps you focus on the design patterns that naturally adapt to your needs, and on the patterns that uniquely benefit from the features of C++. Armed with the knowledge of these patterns, you’ll spend less time searching for solutions to common problems and tackle challenges with the solutions developed from experience. You’ll also explore that design patterns are a concise and efficient way to communicate, as patterns are a familiar and recognizable solution to a specific problem and can convey a considerable amount of information with a single line of code. By the end of this book, you’ll have a deep understanding of how to use design patterns to write maintainable, robust, and reusable software.
Table of Contents (26 chapters)
1
Part 1: Getting Started with C++ Features and Concepts
5
Part 2: Common C++ Idioms
10
Part 3: C++ Design Patterns
18
Part 4: Advanced C++ Design Patterns

Visitors in modern C++

As we have just seen, the Visitor pattern promotes the separation of concerns; for example, the order of serialization and the mechanism of serialization are made independent, and a separate class is responsible for each. The pattern also simplifies code maintenance by collecting all code that performs a given task in one place. What the Visitor pattern does not promote is code reuse with no duplication. But that’s the object-oriented Visitor pattern, before modern C++. Let’s see what we can do with the generic capabilities of C++, starting from the regular Visitor pattern.

Generic Visitor

We are going to try to reduce the boilerplate code in the implementation of the Visitor pattern. Let’s start with the accept() member function, which must be copied into every visitable class; it always looks the same:

class Cat : public Pet {
  void accept(PetVisitor& v) override { v.visit(this); }
};

This function cannot be moved...