Table Of ContentEarly Praise for Resourceful Code Reuse
Resourceful Code Reuse offers readers a quick way to understand how code is
compiled and linked using the C language within the modern context of consuming
and processing JSON.
➤ Mike Riley
President, Ingenious Solutions, Inc.
Every developer should know about the concepts described in this book. Even if
you don’t use C and Python in your daily work, you will learn something about
software development and how to reuse code.
➤ Dominik Hauser
Author of Build Location-Based Projects for iOS
Everyone can code, but writing beautiful code requires code reuse skills. Whether
you are starting coding or you have broad experience, this book offers a practical
guide that allows you to optimize your code by applying code reuse techniques.
➤ Jose Arturo Mora Soto
Senior Curriculum Engineer, 2U Inc.
We've left this page blank to
make the page numbers the
same in the electronic and
paper books.
We tried just leaving it out,
but then people wrote us to
ask about the missing pages.
Anyway, Eddy the Gerbil
wanted to say “hello.”
Resourceful Code Reuse
Write → Compile → Link → Run
Dmitry Zinoviev
The Pragmatic Bookshelf
Raleigh, North Carolina
Many of the designations used by manufacturers and sellers to distinguish their products
are claimed as trademarks. Where those designations appear in this book, and The Pragmatic
Programmers, LLC was aware of a trademark claim, the designations have been printed in
initial capital letters or in all capitals. The Pragmatic Starter Kit, The Pragmatic Programmer,
Pragmatic Programming, Pragmatic Bookshelf, PragProg and the linking g device are trade-
marks of The Pragmatic Programmers, LLC.
Every precaution was taken in the preparation of this book. However, the publisher assumes
no responsibility for errors or omissions, or for damages that may result from the use of
information (including program listings) contained herein.
For our complete catalog of hands-on, practical, and Pragmatic content for software devel-
opers, please visit https://pragprog.com.
The team that produced this book includes:
CEO: Dave Rankin
COO: Janet Furlow
Managing Editor: Tammy Coron
Development Editor: Adaobi Obi Tulton
Copy Editor: Corina Lebegioara
Founders: Andy Hunt and Dave Thomas
For sales, volume licensing, and support, please contact [email protected].
For international rights, please contact [email protected].
Copyright © 2021 The Pragmatic Programmers, LLC.
All rights reserved. No part of this publication may be reproduced, stored in a retrieval system,
or transmitted, in any form, or by any means, electronic, mechanical, photocopying, recording,
or otherwise, without the prior consent of the publisher.
ISBN-13: 978-1-68050-820-8
Encoded using the finest acid-free high-entropy binary digits.
Book version: P1.0—April 2021
Contents
Acknowledgments . . . . . . . . . . . vii
Preface . . . . . . . . . . . . . . ix
Introduction: Why Reuse Code? . . . . . . . . xi
1. Reuse Code at Compile Time (C and Python) . . . . . 1
Arranging Source and Header Files (the C Way) 1
Modularizing Code (the Python Way) 9
2. Reuse Code at Link Time (C Only) . . . . . . . 13
Compiling Object Files 13
Building Static Libraries 21
Building Dynamic Libraries 29
3. Reuse Code at Runtime (C and Python) . . . . . . 35
Harnessing Dynamic Loading 35
Getting a Taste of Remote Procedure Calls 40
Bibliography . . . . . . . . . . . . . 49
Acknowledgments
This is my second book edited by Adaobi Obi Tulton and, just like the first
book, it would not be possible without her enthusiasm, dedication, and
highest professionalism. Thank you, Adaobi.
I am grateful to my reviewers (in alphabetical order): Ludovico Fischer,
Dominik Houser, Andy Lester, Mike Riley, Jose Arturo Mora Soto, and Ilya
Usvyatsky. Their criticism was refreshening and energizing. Their reviews
greatly improved the structure, usability, and style of the book. Thank you,
reviewers.
My wife, Anna; my children, Eugenia and Roman; my colleagues from Suffolk
University (especially Pelin Bicen) and my friends (especially Dmitry and Tanya
Cherevik) provided much-needed emotional support. Thank you, my support-
ers.
Last but not least, I am grateful to Desbenoit thenounproject.com/term/reuse/6786/
for the royalty-free image on page 47.
report erratum • discuss
Preface
I took my first and only academic course in software engineering in the fall
of 1994. The course was taught by Professor Peter Henderson, who had spent
a quarter of a century at Stony Brook University and retired shortly after my
graduation. The course was taught in Smalltalk, the mother of all object-ori-
ented languages, and was undeniably excellent. Sadly, I have never had
another chance to write a line of code in Smalltalk and barely remember what
it looked like.
What I do remember is the mantra that Professor Henderson recited over and
over again, until it got imprinted into my mind, from the top of my head to
my fingertips: “Thou shalt use make files and reuse your code.” Ever since,
I’ve started every new non-trivial project by writing a makefile and spending a
ridiculous amount of time dissecting the job into potentially reusable units.
In this book, I want to share with you my passion for code reuse and code
organization and the skills that support that passion.
About the Reader
This book is mainly intended for beginner through intermediate software
developers in C and, to a much lesser extent, in Python, who want to achieve
higher productivity, better code quality, and more flexible and adaptable
products by reusing and organizing previously written code. Experience with
command-line software development tools is helpful but not required.
About the Book
After the mandatory introduction that sets the scene for the story, the book
goes over three stages of small project development: editing (producing the
project’s text in a programming language), compiling (converting the text into
object files with machine code), and linking (combining the pre-compiled
object files into one executable program file). Any unit produced at any stage
can be reused and shared at a later stage, including the runtime when there
is no more development. The rest of the book is organized into three chapters
report erratum • discuss
Preface • x
focused on these topics: compile-time reuse, link-time reuse, and runtime
reuse.
I tried to keep the chapters as independent as possible but still ended up
with some backward and forward references. The forward references are not
so essential for understanding the material, but if you open the book in the
middle and come across a backward reference that you do not recognize, I
strongly suggest visiting it.
About the Software
To compile and run the C examples mentioned in the book, you need a decent
C compiler (gcc is the best, but Intel and Microsoft would probably work, too)
and a set of C development tools: maker (make), linker (ld), file, strip, ldd, and
ranlib. The GNU development toolset works marvels; other toolsets may or may
not work. All examples in the book have been tested on a Linux computer
but will most likely work on macOS.
For the Python examples, a Python-3.x interpreter (python) is all you want. No
third-party modules are required.
Shall we start?
Dmitry Zinoviev
[email protected]
February 2021
report erratum • discuss
