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

ScopeGuard and exceptions

The ScopeGuard pattern is designed to correctly run various cleanup and rollback operations automatically upon exiting a scope, no matter what caused the exit—normal completion by reaching the end of the scope, an early return, or an exception. This makes writing error-safe code in general, and exception-safe code in particular, much easier; as long as we queued up the right guards after every action, the correct cleanup and error handling will automatically happen. That is, of course, assuming that ScopeGuard itself is functioning correctly in the presence of exceptions. We are going to learn how to make sure it does and how to use it to make the rest of the code error-safe.

What must not throw an exception

We have already seen that the commit() function that is used to commit an action and disarm the rollback guard must never throw an exception. Fortunately, that is easy to guarantee since all this function does is set a flag. But what happens...