Clean C++ Sustainable Software Development Patterns and Best Practices with C Stephan Roth

Transcription

1 Clean C++ Sustainable Software Development Patterns and Best Practices with C++ 17 Stephan Roth

2 Clean C++: Sustainable Software Development Patterns and Best Practices with C++ 17 Stephan Roth Bad Schwartau, Schleswig-Holstein, Germany ISBN-13 (pbk): ISBN-13 (electronic): DOI / Library of Congress Control Number: Copyright 2017 by Stephan Roth This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. Trademarked names, logos, and images may appear in this book. Rather than use a trademark symbol with every occurrence of a trademarked name, logo, or image we use the names, logos, and images only in an editorial fashion and to the benefit of the trademark owner, with no intention of infringement of the trademark. The use in this publication of trade names, trademarks, service marks, and similar terms, even if they are not identified as such, is not to be taken as an expression of opinion as to whether or not they are subject to proprietary rights. While the advice and information in this book are believed to be true and accurate at the date of publication, neither the authors nor the editors nor the publisher can accept any legal responsibility for any errors or omissions that may be made. The publisher makes no warranty, express or implied, with respect to the material contained herein. Cover image by Freepik ( Managing Director: Welmoed Spahr Editorial Director: Todd Green Acquisitions Editor: Steve Anglin Development Editor: Matthew Moodie Technical Reviewer: Marc Gregoire Coordinating Editor: Mark Powers Copy Editor: Karen Jameson Distributed to the book trade worldwide by Springer Science+Business Media New York, 233 Spring Street, 6th Floor, New York, NY Phone SPRINGER, fax (201) , orders-ny@springer-sbm.com, or visit Apress Media, LLC is a California LLC and the sole member (owner) is Springer Science + Business Media Finance Inc (SSBM Finance Inc). SSBM Finance Inc is a Delaware corporation. For information on translations, please rights@apress.com, or visit rights-permissions. Apress titles may be purchased in bulk for academic, corporate, or promotional use. ebook versions and licenses are also available for most titles. For more information, reference our Print and ebook Bulk Sales web page at Any source code or other supplementary material referenced by the author in this book is available to readers on GitHub via the book s product page, located at For more detailed information, please visit Printed on acid-free paper

3 To Caroline and Maximilian: my beloved and marvelous family.

4 Contents at a Glance About the Author... xiii About the Technical Reviewer...xv Acknowledgments...xvii Chapter 1: Introduction... 1 Chapter 2: Build a Safety Net... 9 Chapter 3: Be Principled Chapter 4: Basics of Clean C Chapter 5: Advanced Concepts of Modern C Chapter 6: Object Orientation Chapter 7: Functional Programming Chapter 8: Test-Driven Development Chapter 9: Design Patterns and Idioms Appendix A: Small UML Guide Bibliography Index v

5 Contents About the Author... xiii About the Technical Reviewer...xv Acknowledgments...xvii Chapter 1: Introduction... 1 Software Entropy... 2 Clean Code... 3 Why C++?... 4 C++11 The Beginning of a New Era... 4 Who This Book Is For... 5 Conventions Used in This Book... 5 Sidebars... 5 Notes, Tips, and Warnings... 6 Code Samples... 6 Companion Website and Source Code Repository... 7 UML Diagrams... 7 Chapter 2: Build a Safety Net... 9 The Need for Testing... 9 Introduction into Testing Unit Tests What about QA? Rules for Good Unit Tests Test Code Quality Unit Test Naming vii

6 Contents viii Unit Test Independence One Assertion per Test Independent Initialization of Unit Test Environments Exclude Getters and Setters Exclude Third-Party Code Exclude External Systems And What Do We Do with the Database? Don t Mix Test Code with Production Code Tests Must Run Fast Test Doubles (Fake Objects) Chapter 3: Be Principled What Is a Principle? KISS YAGNI DRY Information Hiding Strong Cohesion Loose Coupling Be Careful with Optimizations Principle of Least Astonishment (PLA) The Boy Scout Rule Chapter 4: Basics of Clean C Good Names Names Should Be Self-Explanatory Use Names from the Domain Choose Names at an Appropriate Level of Abstraction Avoid Redundancy When Choosing a Name Avoid Cryptic Abbreviations Avoid Hungarian Notation and Prefixes Avoid Using the Same Name for Different Purposes... 48

7 Contents Comments Let the Code Tell a Story Do Not Comment Obvious Things Don t Disable Code with Comments Don t Write Block Comments The Rare Cases Where Comments Are Useful Functions One Thing, No More! Let Them Be Small Function Naming Use Intention-Revealing Names Arguments and Return Values About Old C-style in C++ Projects Prefer C++ Strings and Streams over Old C-Style char* Avoid Using printf(), sprintf(), gets(), etc Prefer Standard Library Containers over Simple C-style Arrays Use C++ casts Instead of Old C-Style Casts Avoid Macros Chapter 5: Advanced Concepts of Modern C Managing Resources Resource Acquisition Is Initialization (RAII) Smart Pointers Avoid Explicit New and Delete Managing Proprietary Resources We Like to Move It What Are Move Semantics? The Matter with Those lvalues and rvalues rvalue References Don t Enforce Move Everywhere The Rule of Zero ix

8 Contents The Compiler Is Your Colleague Automatic Type Deduction Computations during Compile Time Variable Templates Don t Allow Undefined Behavior Type-Rich Programming Know Your Libraries Take Advantage of <algorithm> Take Advantage of Boost More Libraries That You Should Know About Proper Exception and Error Handling Prevention Is Better Than Aftercare An Exception Is an Exception Literally! If You Can t Recover, Get Out Quickly Define User-Specific Exception Types Throw by Value, Catch by const Reference Pay Attention to the Correct Order of Catch-Clauses Chapter 6: Object Orientation Object-Oriented Thinking Abstraction the Key to Master Complexity Principles for Good Class Design Keep Classes Small Single Responsibility Principle (SRP) Open-Closed Principle (OCP) Liskov Substitution Principle (LSP) Interface Segregation Principle (ISP) Acyclic Dependency Principle Dependency Inversion Principle (DIP) Don t Talk to Strangers (Law of Demeter) Avoid Anemic Classes x

9 Contents Tell, Don t Ask! Avoid Static Class Members Chapter 7: Functional Programming What Is Functional Programming? What Is a Function? Pure vs. Impure Functions Functional Programming in Modern C Functional Programming with C++ Templates Function-Like Objects (Functors) Binders and Function Wrappers Lambda Expressions Generic Lambda Expressions (C++14) Higher-Order Functions Map, Filter, and Reduce Clean Code in Functional Programming Chapter 8: Test-Driven Development The Drawbacks of Plain Old Unit Testing (POUT) Test-Driven Development as a Game Changer The Workflow of TDD TDD by Example: The Roman Numerals Code Kata The Advantages of TDD When We Should Not Use TDD Chapter 9: Design Patterns and Idioms Design Principles vs. Design Patterns Some Patterns, and When to Use Them Dependency Injection (DI) Adapter Strategy Command Command Processor xi

10 Contents Composite Observer Factories Facade Money Class Special Case Object (Null Object) What Is an Idiom? Some Useful C++ Idioms Appendix A: Small UML Guide Class Diagrams Class Interface Association Generalization Dependency Components Stereotypes Bibliography Index xii

11 About the Author Stephan Roth, born on May 15, 1968, is a passionate coach, consultant, and trainer for Systems and Software Engineering with German consultancy company oose Innovative Informatik eg located in Hamburg. Before he joined oose, Stephan worked for many years as a software developer, software architect, and systems engineer in the field of radio reconnaissance and communication intelligence systems. He has developed sophisticated applications, especially for distributed systems with ambitious performance requirements, and graphical user interfaces using C++ and other programming languages. Stephan is also a speaker at professional conferences and author of several publications. As a member of the Gesellschaft für Systems Engineering e.v., the German chapter of the international Systems Engineering organization INCOSE, he is also engaged in the Systems Engineering community. Furthermore, he is an active supporter of the Software Craftsmanship movement and concerned with principles and practices of Clean Code Development (CCD). Stephan Roth lives with his wife Caroline and their son Maximilian in Bad Schwartau, a spa in the German federal state of Schleswig-Holstein near the Baltic Sea. You can visit Stephan s website and blog about Systems Engineering, Software Engineering, and Software Craftsmanship via the URL roth-soft.de. Please note that the articles there are mainly written in German. On top of that, you can contact him via or follow him at the networks listed below. stephan@clean-cpp.com ( Google+ Profile Page: LinkedIn: xiii

12 About the Technical Reviewer Marc Gregoire is a software engineer from Belgium. He graduated from the University of Leuven, Belgium, with a degree in "Burgerlijk ingenieur in de computer wetenschappen" (equivalent to Master of Science in engineering in computer science). The year after, he received a master s degree, cum laude, in artificial intelligence at the same university. After his studies were completed, Marc started working for a software consultancy company called Ordina Belgium. As a consultant, he worked for Siemens and Nokia Siemens Networks on critical 2G and 3G software running on Solaris for telecom operators. This required working in international teams stretching from South America and the United States to EMEA and Asia. Marc is now working for Nikon Metrology on industrial 3D laser scanning software. His main expertise is C/C++, and specifically Microsoft VC++ and the MFC framework. He has experience in developing C++ programs running 24x7 on Windows and Linux platforms: for example, KNX/ EIB home automation software. Next to C/C++, Marc also likes C# and uses PHP for creating web pages. Since April 2007, he has received the yearly Microsoft MVP (Most Valuable Professional) award for his Visual C++ expertise. Marc is the founder of the Belgian C++ Users Group ( author of Professional C++ and a member of the CodeGuru forum (as Marc G). He maintains a blog on xv

13 Acknowledgments Writing a book like this one is never just the work of an individual person, the author. There are always numerous, fabulous people who contribute significantly to such a great project. First of all, I would like to thank Steve Anglin of Apress. Steve contacted me in March 2016 and has persuaded me to continue my book project with Apress Media LLC, which has been self-published at Leanpub until then. That was such great luck, and I thank you, dear Steve. In July 2016 the contracts were signed. Nevertheless, I would also like to thank the superb Leanpub self-publishing platform that served some years as a kind of "incubator" for this book. Next, I would like to thank Mark Powers, Editorial Operations Manager at Apress, for his great support during the writing of the manuscript. Mark was not only always available to answer questions: his incessant follow-up on the progress of the manuscript was a positive incentive for me. I am very grateful to you, dear Mark. In addition, many thanks also to Matthew Moodie, Lead Development Editor at Apress, who has provided proper help throughout the whole book development process. A special thank you goes out to my technical reviewer Marc Gregoire. Marc, thank you for critically examining every single chapter. You ve found many issues that I probably would have never found. You pushed me hard to improve several sections, and that was really valuable to me. Of course, I would also like to say a big thank you to the whole production team at Apress. They ve done an excellent job regarding the finalization (copy editing, indexing, composition/layout, etc.) of the whole book until the distribution of the final print (and ebook) files. Of course, I also thank all my colleagues at oose. Thank you for the many inspiring discussions. Last but not least, I would like to thank my beloved and unique family, especially for their understanding that a book project takes a great deal of time. Maximilian and Caroline, you re just wonderful. xvii