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

Why constructors cannot be virtual

We already understand how polymorphism works—when a virtual function is called through a pointer or a reference to the base class, that pointer or reference is used to access the v-pointer in the class. The v-pointer is used to identify the true type of the object, that is, the type that the object was created with. It could be the base class itself, or any one of the derived classes. The member function on that object is actually called. So, why can’t the same be done for constructors? Let’s investigate this.

When does an object get its type?

It is pretty easy to understand why the process that we described previously cannot work for creating virtual constructors. First of all, it is evident from the description of the preceding process—as a part of it, we identify the type that the object was created with. That can only happen after the object is constructed—before construction, we don’t have an object...