Write Portable Code

Write Portable Code 397

Posted by samzenpus on Wednesday November 09, 2005 @02:37PM from the measure-twice-write-once dept.

Simon P. Chappell writes "Much as a certain large software company located in the North-West of the United States of America might wish otherwise, there are many different operating systems and platforms in use in the world today. Software these days needs to able to operate in a disparate environment, either by communicating with these other platforms or by running on them or, increasingly, doing both. The Information Systems industry is making good progress with the communication half of the problem (even if a lot of it seems to involve large amounts of XML), but it is still struggling with the issues inherent with writing portable code. Brian Hook's contribution to all of this is Write Portable Code , which according to it's subtitle is an introduction to developing software for multiple platforms." Read on for the rest of Simon's review.

Write Portable Code
author	Brian Hook
pages	248 (14 page index)
publisher	No Starch Press
rating	8/10
reviewer	Simon P. Chappell
ISBN	1593270569
summary	I recommend this book to anyone working with portable code.

This is a book for computer programmers who write software designed to run on multiple platforms. It's also for programmers who suspect that their software may need to run on different platforms. This brings the book onto the radar for free and open source software authors, as they seek to create software that does not trap their end users into using specific operating systems. The Structure

There is a good progression shown in the eighteen chapters of the book. The first couple of chapters introduce the reader to portability concepts and then to some of the specific portability features of ANSI C and C++ that are used throughout the rest of the book.

The middle chapters of the book, cover individual portability topics. Some of these topics are the obvious ones, like Floating Point numbers, Networking, Operating System, File System and Dynamic Libraries. Other topics are less intuitively associated with portability, but when you read the chapter, it's inclusion is both obvious and necessary. These subjects include Source Code Management, Compilers, Scalability and Data. There is more to portability than many of us might suspect.

The last two chapters look at some alternative ways of getting portability. Scripting languages are discussed and the pros and cons of each ones portability is weighed. Lastly the use of cross-platform libraries and toolkits is addressed. Quite apropos given that the book's author is also the author of a cross platform library.

As an example of the thoughtful approach taken in this book, lets' take a look at the chapter on scripting languages. It's about the shortest chapter in the book, but representative of the approach that Mr. Hook brings to his work. This chapter takes a very honest look at the portability and cross-platform aspects of using scripting languages. There are advantages and disadvantages to the use of scripting languages. The advantages include everything that is a disadvantage of low-level languages like C/C++. Scripting languages do not require you to worry about about memory allocation, bindings, System API calls or any of the other bugbears of a low-level language programmer's life. The disadvantages of scripting languages naturally include performance, given their interpreted natures, a general lack of tools, such as development environments or IDEs and their tendency to sit high above the operating system with a corresponding detachment from low-level facilities and services of that same operating system. Mr. Hook's choice of scripting languages to consider was interesting. I expected Ruby and Python; both popular and capable in their own right. The inclusion of JavaScript/ECMAScript was also not too unexpected, now that standalone versions are bubbling up and becoming available. The real surprise, albeit a pleasant one, was the inclusion of Lua; a scripting language designed for platform portability and which seems to have managed to fully mature without making a blip on most geeks radar screens.

I like that Mr. Hook has experience writing portable software. This matched with his authorship of the Portable Open Source Harness (POSH) portability library and his contributions to the Simple Audio Library (SAL) gives a great deal of credence to his writing.

This is a solid "doing" book. Mr. Hook is under no illusion that he's writing an introduction to programming. This book has a consistent purpose to take experienced programmers and fully equip them to deal with portability and it does not deviate from this in the slightest.

The layout of the book is first rate, with clear typography, comfortable spacing, clear diagrams and tables and nicely highlighted callouts. I did not notice any obvious typos or glitches in the book. While the look of a book is not the author's fault if it is below par, a well presented book can enhance the reading and learning experience.

The examples are as realistic as possible. While some of the examples to teach principles might be simpler, they are typically backed up with examples from either the POSH or SAL projects, showing real world portability coding. The level of C/C++ required to understand the examples is higher than many books that I've read. That's not to say that the code seems obfuscated, but it's code that is taking into account aspects of the real world and is, by necessity, not simple. A further positive quality of the code examples is that they're very well explained; well enough that an inexperienced programmer with determination could follow them and come to an understanding.

Appendix B contains a summary of all of the portability rules presented through the book. There are twenty rules and each is reprised with a small explanation/reminder of it's application. An example: Rule 4 - "Never read or write structures monolithically from or to memory. Always read and write structures one element at a time, so that endian, alignment, and size differences are factored out."

If you're looking for more of a fluffy "about" book, then this is not it. This is not a complaint, rather I offer it as something to consider, before you buy what you might otherwise think is a beginner's book.

I must reiterate the non-trivial C/C++ example code the book contains. This book is for serious programmers and is not afraid to role up it's sleeves and cut real code.

This is a very well written and very readable book. There are many aspects to the subject matter of portability and Mr. Hook addresses more of them than many of us had previously suspected existed and addresses them with firm authority. I recommend this book to anyone working with portable code."

You can purchase Write Portable Code from bn.com. Slashdot welcomes readers' book reviews -- to see your own review here, read the book review guidelines, then visit the submission page.

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