The code from the book

You can download the zip file containing all of the code from the book. The zip file is organized by chapter, one subdirectory per chapter. In each subdirectory you will, for the most part, find Ruby files with names like ex1_report.rb or ex15_subclass_test.rb or ex13_account_demo.rb.

The files are numbered so as to roughly follow the order that the code appears in the book. For example, chap01/ex3_vehicle.rb appears in the book before chap01/ex8_delegate.rb.

The files whose names end with “demo” are a bit special. These guys contain the code for the fragmentary, inline examples (as opposed to full classes) that are sprinkled throughout the book – take a look at the code on page 6. These “demo” files actually make use of a couple of utility methods found in the “example.rb” in the root code directory.

The problem I had with fragmentary examples was that I wanted to be sure that the code actually worked, and that the output that I claimed the code produced actually came out of the code, no small feat when you are dealing with more than 100 separate examples. The solution that I came up with was to wrap each little example in a call to a method (defined in example.rb) called example:

example %q{
my_car =


Look closely at the code above and you will see that the example code gets passed to the example method as a string. The example method does two things with that string: first it simply prints it out (so that I could snag the code for inclusion in the book) and then executes it (so that I could snag the output for inclusion in the book). Ah the wonders of Ruby!

Finally, there are a couple of examples in the later parts of the book which just didn’t fit into the ex##_*.rb naming scheme, but these should be pretty self explanatory.

Of course if you have any questions or comments, just email me at russ funny at sign russolsen dot com.