Book Image

Hands-On Design Patterns with C++

By : Fedor G. Pikus
Book Image

Hands-On Design Patterns with C++

By: Fedor G. Pikus

Overview of this book

C++ is a general-purpose programming language designed with the goals of efficiency, performance, and flexibility in mind. 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. The focus of this book is on the design patterns that naturally lend themselves to the needs of a C++ programmer, and on the patterns that uniquely benefit from the features of C++, in particular, the generic programming. Armed with the knowledge of these patterns, you will spend less time searching for a solution to a common problem and be familiar with the solutions developed from experience, as well as their advantages and drawbacks. The other use of design patterns is as a concise and an efficient way to communicate. A pattern is a familiar and instantly recognizable solution to specific problem; through its use, sometimes with a single line of code, we can convey a considerable amount of information. The code conveys: "This is the problem we are facing, these are additional considerations that are most important in our case; hence, the following well-known solution was chosen." By the end of this book, you will have gained a comprehensive understanding of design patterns to create robust, reusable, and maintainable code.
Table of Contents (21 chapters)

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...