About the Book
The Toy Robot exercise was originally developed by Jon Eaves. He explains why he did it in this blog post.
If you're a new Ruby developer who's gone through some basic Ruby tutorials and you're looking for the next thing to build your skills, this book is a great start. It covers the Toy Robot exercise from start to finish, testing with RSpec along the way.
The Toy Robot exercise is commonly used in interviews as the ways to solve it in any language are not as simple as they first may seem. This book covers one implementation of this exercise in Ruby. It is not intended to be the most perfect implementation of the Toy Robot exercise possible, but instead is my personal take on it.
The Toy What Now?
The Toy Robot! It's a very common interview exercise given to new programmers. Here's the variant of the problem's description that we use in the book:
The application is a simulation of a toy robot moving on a square tabletop, of dimensions 5 units x 5 units. There are no other obstructions on the table surface. The robot is free to roam around the surface of the table. Any movement that would result in the robot falling from the table is prevented, however further valid movement commands are still allowed.
The application reads a file using a name passed in the command line, the following commands are valid:
- PLACE X,Y,F
Here's some rules for these commands:
- PLACE will put the toy robot on the table in position X,Y and facing NORTH, SOUTH, EAST or WEST.
- The origin (0,0) is the SOUTH WEST most corner.
- All commands are ignored until a valid PLACE is made.
- MOVE will move the toy robot one unit forward in the direction it is currently facing.
- LEFT and RIGHT rotates the robot 90 degrees in the specified direction without changing the position of the robot.
- REPORT announces the X,Y and F of the robot.
The file is assumed to have ASCII encoding. It is assumed that the PLACE command has only one space, that is PLACE 1, 2, NORTH is an invalid command. All commands must be in upcase, all lower and mixed case commands will be ignored.
All of that may seem a little bit overwhelming but if you break it down into little chunks and tackle those chunks one-at-a-time (like this book does!) it becomes much easier.
Table of Contents
The Toy Robot
- Simplifying the problem
- Setting up our project
- Moving left
- Moving north and south
- Moving in the right direction
- Turn left!
- Turn right!
- Reading commands
- Running commands
- Running the robot
- Verifying the toy robot’s behaviour
The Leanpub 60-day 100% Happiness Guarantee
Within 60 days of purchase you can get a 100% refund on any Leanpub purchase, in two clicks.
See full terms
80% Royalties. Earn $16 on a $20 book.
We pay 80% royalties. That's not a typo: you earn $16 on a $20 sale. If we sell 5000 non-refunded copies of your book or course for $20, you'll earn $80,000.
(Yes, some authors have already earned much more than that on Leanpub.)
In fact, authors have earnedover $12 millionwriting, publishing and selling on Leanpub.
Learn more about writing on Leanpub
Free Updates. DRM Free.
If you buy a Leanpub book, you get free updates for as long as the author updates the book! Many authors use Leanpub to publish their books in-progress, while they are writing them. All readers get free updates, regardless of when they bought the book or how much they paid (including free).
Most Leanpub books are available in PDF (for computers) and EPUB (for phones, tablets and Kindle). The formats that a book includes are shown at the top right corner of this page.
Finally, Leanpub books don't have any DRM copy-protection nonsense, so you can easily read them on any supported device.
Learn more about Leanpub's ebook formats and where to read them