Monday, June 25, 2007

Playa del Carmen


I haven't been around to add to the blog for a while, I was on vacation with my family. I just couldn't pull myself away from the warm sunny tropical beach to fiddle around with the hotel's internet connection and spend time on a post or two.

We went to part of the Yucatan south of Cancun often called the 'Riviera Maya', in the town of Playa del Carmen. The water was warm and clear, the beaches have really made a comeback after last year's hurricane, and the food at our resort was fantastic. Our kids are too small to do some of the larger jungle excursions, but we visited the nerby bird sanctuary Xaman Ha with the family. My daughter and I went horseback riding in the jungle one day as well.

The resorts had three little Hobie cats guests could take out whenever they wanted, as well as several kayaks and sailboards. I tried to take out a cat as often as I could and truly enjoyed sailing the small craft through the clear caribean water between the mainland and Cozumel.

We stayed at the Viva Azteca. It is the smaller of two Viva resorts in Playa del Carmen. Viva is an Italian based company, and it showed through in the variety and quality of food served at the resort. Italians know how to eat.

Getting back meant a pile of e-mail to clean up, but a vacation from the computer, and from blackberries and cell phones is the best.

Thursday, June 7, 2007

Learning Ruby

An Introduction to Ruby

Ruby is a pure object oriented scripting language that runs on most personal computer operating systems including Windows, Linux, Mac OS/X, and BSD. Ruby also runs on most commercial Unix based operating systems as well. Ruby was created in 1995 by Yukihiro Matsumoto, usually referd to as "Matz".

Ruby's popularity grew steadily in the decade following its release. Ruby's growth and popularity are similar to the python language. Both languages have similar goals of simplifying programming. Many programmers have become proficient in both languages, and any perceived 'competition' between the two is usually positive and constructive. Matz mixed together some favorite aspects of other languages he worked with including Perl, Smalltalk, Eiffel, Ada, and Lisp to create Ruby. He wanted a more interactive language that was natural to work in. Something that seemed to 'fit just right'.

I came to ruby late, and through my use of Ruby on Rails in 2005. I've been a proffesional programmer for over a decade, and was most recently building web apps with Java. Rails was like a ray of sunshine in a dark world. The clean, simple approach to programming and the strict adherance to the MVC framework was a great change from the drudgery of configuring large scale Java apps. I was able to pick up Rails pretty quick and become proficcient, but to be better I will need to learn Ruby. So far I am happy to be a 'newbie' in such a great community!

Although I have learned a great deal of Ruby while working with Rails over the last few years, I am going to start over at the begining with Ruby. I've pretty much just picked up Ruby knowledge as I've gone along. I hope that a more rigorous approach to learning Ruby will help me be a better Rails programmer. I'm going to blog about my lessons in Ruby from the start, believing that taking the time to put what I'm learning in writing will help me to understand more.

Most likely I'll just be giving a few readers a nice chuckle at my incompetence.

In an interview with O'Reilly, Matz is quoted as saying:

"I wanted a scripting language that was more powerful than Perl, and more object-oriented than Python. That's why I decided to design my own language."

So far Matz, and the Ruby community are meeting that goal.

You can learn much more about Ruby at the Ruby Language site.

Ruby is free software and is available, either, uder the GPL or the Ruby Software License.

Getting started with Ruby

The first step you need to take in learning Ruby is to get Ruby on your machine.

Mac OS X

Mac OS X comes with Ruby pre-installed. If you don't have it, go to the Apple download site.

To install from source, go to the Source section.


Go to the ruby forge website and download the latest
one click installer and run it.


Linux distros usually have ruby installed already. If you need to install it, its best to use your distro's package management system:

Debian Gnu/Linux
 $ apt-get install ruby irb rdoc

RPM distros
Download an RPM from RPM Find and install with
 $ rpm -Uhv ruby-*.rpm
(You can also use something like yum, Yast, or apt4rpm if they are on your distro)

Gentoo Linux
 $ emerge ruby

Go to the Source section.


Ruby is part of the FreeBSD ports collection. You can install it with:

$ cd /usr/ports/lang/ruby

$ make && make install

Source (good for all UNIX)

Get the latest source code for Ruby ruby-1.8.6.tar.gz.

Un-tar the source code

$ tar -xvzf ruby-1.8.6.tar.gz

To install, cd into the resulting library just do the usual three step:

$ configure; make; make install

Your First Ruby Program

Use your favorite text editor to create a file called ruby_hello.rb. Type this one line in the file:

puts 'Hello World!'

save the file and run it at the command line with the command:

$ ruby ruby_hello.rb
Hello World!

You can also run the ruby code directly from the command line with the -e switch, just like in perl:

$ ruby -e "puts 'Hello world'"

Or use irb, the ruby interactive shell:

$ irb
>> puts 'Hello World!'
Hello World!
=> nil

Going back to our text editor, let's add some comments. Ruby single line comments begin with a #. Everything on the line after the # is a comment:

# the classic first program

puts 'Hello World!' #print a greeting

Multi-line comments are rarely used in Ruby. Multi-line or block comments are delimited with '=begin' and '=end':

# the classic first program

puts 'Hello World!' #print a greeting

This ruby program is

© copyrighted by me, 2007.

Or it would be if there

weren't already millions

of other programs exactly

like it, many of which are

in the public domain already.

save the file and run it at the command line and you'll see the exact same result as before:

$ ruby ruby_hello.rb
Hello World!

So that's lesson one. Installing Ruby, writing and running the obligatory 'Hello World!' program to see if the installation went well. If you had any problems, check out the Ruby language page, or join the Ruby community and check in the mailing lists, chat rooms or with the local Ruby Users Group for help.

Tuesday, June 5, 2007

Ruby Yield

Yield is one of the most powerful concepts implemented in the Ruby programming language. Yield lets you branch from within a method and execute some external code, then return to the original code in the first method.

What's so special about yield in Ruby? You could get the same branch and return flow by just executing a method call in java, or a function call in C.

Heck, COBOL's PERFORM verb implements branch and return behavior. So what's up with yield?

Well, the behavior of what you branch to is set in stone with all those other techniques, but is undetermined until coded in Ruby. Yield is kind of like a place holder that says "I'm going to branch off and do something here, but I don't know what I'm going to do yet".

Maybe some examples will help make it more clear. Here is a Ruby method with some yields coded in it, then the code to invoke the method and the block of code to invoke when the yield is encountered:

def block1
puts "Start of block1..."
puts "End of block1."

block1 {puts "yielding..."}

Running this code would produce the following output:

Start of block1...
End of block1.

So block1 executes it's first line and prints "Start of block1...", then it executes the yields which branch to the block of code outside block1 but associated with it at run time, then comes back and prints "End of block1."

OK that's, fine but isn't that functionally the same as the following code:

def block2
puts "Start of block2..."
put_it("in put_it called method...")
put_it("still in put_it called method...")
puts "End of block2."

def put_it(text)
puts text


Running this second set of code produces the following:

Start of block2...
in put_it called method...
still in put_it called method...
End of block2.

For the most part, these are pretty much the same. However without having to redefine any methods I could immediately execute the block1 method with a different block associated with it. The yield would branch and execute this newly associated logic:

block1 {require 'time'

This produces the output:

Start of block1...
Tue, 05 Jun 2007 19:20:35 GMT
Tue, 05 Jun 2007 19:20:35 GMT
End of block1.

The hard coded function call in block2 forever ties the branching logic to the put_it function. To get different behavior you would need to either change the function call in block2 to call a different function, or change the behavior of the function put_it. This second way is brittle because it could break code elsewhere that calls put_it. The first is cumbersome and possibly brittle.

Ruby's yield is a wonderful construct.

What about when you don't want to branch, but want the other functionality in the block1 code to be executed? Can you just run the code without the associated block?

Let's see what happens. Running block1 without an attached block for the yield to associate to:


This produces the result:

Start of block1...
LocalJumpError: no block given
from :3:in 'block1'
from :7
from :0

We get a 'no block given' error at line 3 in method 'block1'. Line 3 is our first yield in the block1 method.

What to do?

We can wrap the yield in an if statement and check for the presence of a block using the block_given? conditional. It returns true if a block was given with the method call, or false if not.

For this example I'll use a slightly more idiomatic way of checking for the presence of a block in ruby:

def block3
puts "Start of block3..."
yield if block_given?
puts "End of block3."

now if we run the code with a block:

block3 { puts "yielding" }

or without:


It works both times producing:

Start of block3...
End of block3.


Start of block3...
End of block3.

This will make your methods less brittle and more agile.

Ruby's yield is worth getting to know. You can learn more here and here. Many of Ruby's built in methods contain yields that allow you to associate blocks with them producing added functionality at run time.

Monday, June 4, 2007

The Beauty of Ruby

The Beauty of Ruby

I've been working more and more with Ruby on Rails. I'm hoping to be able to work full time with it in the next few years, but for now I'll just have to keep sneaking it into some of the bigger things I get paid to do.

Its too bad because Rails and Ruby could really help some of the clients I work for. I really haven't been this excited about a programming language since I learned C back in the Eighties!

One of the main benefits of Ruby on Rails is how opinionated Rails is. Rails does not try to be everything to everyone. It is trying to meet most of the needs of the average web app, but not trying to give into everyone's slightest whim. The coding needed to provide for most of what you need will be simple and straightforward with Rails. If you want more esoteric fluff, you can use J2EE. There are plenty of alternative solutions, but if 8 out of 10 apps you write fit in the middle, why are you forced to carry the luggage and infrastructure to support those few times the exotic stuff is needed.

Working with Rails is like working with a framework that imposes the KISS principle on your apps. It really results in savings and efficiency.

As I've worked more with Rails, I've begun to truly appreciate Ruby. Like many people in the last few years I came to Ruby through Rails. I started using Ruby as just another language. Most of what you know in any given language is available in any other. The biggest differences are between the procedural and the object oriented languages, but you might be surprised and how similar even these are in practice. Take Java for example. It is a fairly object oriented language. Its not pure OO, and it doesn't claim to be. Java's basic types are not objects. You know strings, floats, characters, and such. However Java is a pretty good example of a modern OO language. However you'll notice that quite a bit of Java was written by people who think like procedural programmers. take a walk through Java's network classes and you'll see the same kind of coding I was doing back when I learned C in the 1980's.

I shouldn't complain because I certainly wouldn't have done a better job. Heck, I wouldn't have done nearly as good a job as the people at Sun did.


With Ruby everything is an object. You cannot cheat. You have to code in OO style. Better yet Ruby truly embraces its Object Oriented-ness! You often don't call a method on an object, the method invokes its own method on itself. For Java's class Math one of the methods is abs, a function that lets you compute the absolute value of a number. For example for an integer the function looks like:

Java code:

public final class Math {
public static int abs(int a);
public static long abs(long a);
public static float abs(float a);
public static double abs(double a);

You would use this method on an integer like this:

Java code:

public class MathExample{
public static void main(String[] args) {

int i = -7;
System.out.println("i is " + i);
System.out.println("" + i + " is " + Math.abs(i));

This is pretty standard stuff. It should be easy enough for any programmer to understand. For output you would get something like:

i is -7
|-7| is 7

What's not object oriented about that? Math is a class. abs is a method of class Math. Heck abs is even multiply defined so the same method can be applied to multiple data types! Math.abs() that is object oriented!

Yes it is.

So what's Ruby got?

Let's just look at How Ruby would do it first:

Ruby code:

puts 'i is ' + (-7).to_s
puts 'i is ' (-7.abs).to_s

The heart of that is when negative seven calls its method abs on itself

puts -7.abs

Yep, that's all folks. Remember Ruby is a pure object oriented language, so the integer '-7' is an object. The object '-7' is of type int and has a method called abs. -7 is calling its own method on itself! Lucky number seven.

The puts (for put string) looks like a normal function call with a function name followed by the object to perform the function on, but we could give objects a 'puts' themself method. You can see how we used the numeric object's 'to_s' method on itself to turn it into a string. The object that the puts function was operating on was not enclosed in parentheses as they are optional in ruby.

If you don't believe me, give it a try yourself. If you follow that link you will be on a site that lets you try out Ruby code at an irb prompt, thanks to Why the Lucky Stiff.

How does Ruby do it?

Well, lets look into the class definitions in the Ruby api and look up how abs is implemented in Ruby (remember Ruby is written is C):

* call-seq:
* fix.abs -> aFixnum
* Returns the absolute value of fix.
* -12345.abs #=> 12345
* 12345.abs #=> 12345

static VALUE
VALUE fix;
long i = FIX2LONG(fix);

if (i < 0) i = -i;

return LONG2NUM(i);

That's the implementation of the absolute value behavior for fixnums. All of Ruby's numeric types get an appropriate form of this behavior. Every numeric type in Ruby has the ability to calculate its own absolute value. As I use Ruby more and more, I am starting to truly appreciate the joys of object oriented programming.

There is truth in beauty.