Ruby on Rails for Java Developers

Ruby on Rails for Java Developers

Ruby is a language. Rails is a framework. Ruby is beneficial to speed developer productivity. It's "dog-slow" but future versions should be faster. Ruby version 2.0 will be faster but right now 1.8.6 is available. JRuby, which is Ruby running a Java VM, is slower than Ruby. This session began by heavily going over the Ruby language. The presenter stressed how important it was to know Ruby rather than just Rails. He mentioned that Rails will make a developer very productive and can keep a developer from learning Ruby well. However, knowing Ruby is the key.

This session quickly covered language syntax using an interpreter. However, it was difficult to envision how a large project is written.

Part I (The Ruby Language)
Ruby is an open, open-source, elegant, object-oriented, and dynamic. Open meaning the entire language is available to you at all times. Can code in an "irb" shell. Presenter explained an experience porting a typical Java project that took months to code to Ruby in a weekend. Many Java code examples consisting of numerous lines of code were reduced by 80-90 percent. This is because Ruby is an implicit language rather than an explicit language. For example, if you create a class to access a database column, the methods to read, write, update, delete are already coded.

In terms of a language, Ruby supports collections, blocks, classes, objects, inheritance, require (i.e. import), case expression, looping, each, hashing. Flow can be controlled using if, while/until. The for loop is handled using ranges and steps. Ex. (1..5).each {|x| puts x*x} or ('A'..'I').step(2) {|x| print x}. Ruby also handles the case statement.

I'm not sure how this works but the rdoc and ri command will display language documentation (i.e. javadoc).

Here's an example to see Ruby within IRB, which I think is an interpreter:

$irb
irb(main):001:0> puts 'Hello, world!'
Hello, world!

irb(main):002:0> s = "Steve"

irb(main):003:0> puts "Hello, #{s}"
Hello, Steve

No compiling, jaring, etc...

Example of a class:
class Person
attr_accessor :firstname, :lastname
def fullname
"#{firstname} #{lastname}"
end
end

Ruby loads libraries directly. This is done with the "require" method. This is done in Java with the "import" statement, right. NO. The "import" statement is just an alias so you don't need to use the entire package.

Ruby has "introspection." Writing [String].instance_methods will return 142 methods that are available to a String. Ruby can handle overflow. You can set a variable as a number and it will be a "Fixnum", which is like a primitive int. If you make the number large enough, it will become a "Bignum", like a primitive long. Why doesn't Java do this? Because in 1995 when Java was trying to prove itself, speed was an issue and primitives were created. Ruby is type safe. C isn't. C says I know what I'm doing and the entire machine can pay.


Java program to print args:
public class PrintArgs {
public static void main(String[] args){

for (int n=0; n System.out.println(args[n]);
}
}

Ruby program to print args:
ARGV.each {|x| puts x}

Find all the numbers between 1-10 that are odd:
(1..10).find_all {|x| x%2 == 1}

Good URL's:
http://www.ruby-doc.org
http://www.ruby-doc.org/core
http://www.ruby-doc.org/stdlib
http://www.ruby-doc.org/docs/ProgrammingRuby/
http://api.rubyonrails.org/
http://rubyforge.org/
http://www.rubygarden.org/ruby?Irb/TipsAndTricks

Book "Rails for Java Developers" by Stuart Halloway (the presenter)

Part II - Rails
Rails is a full model-view-controller framework built in Ruby. It has a great out-of-box experience and supports a number of databases. By generating the framework, a number of functional components are created. Rails applies "Convention Over Configuration" and generates a lot of code. An example was shown coding a Person object with a first name, middle initial, and last name. It was just 3-5 lines of code. By generating the Rails framework, a web site was generated to display, modify, and update data in the database. From this point, Cascading Style Sheets are used to create an attractive web site.

The coding and scripting did not appear intuitive and was difficult to follow in just a few hour session. However, demonstrating how code often rewritten in data access objects is automatically generated in Rails was apparent. A Rails project can be "stubbed" by generating a project. This generates a mvc and helpers, along with database configuration files, test automation code, etc.

Getting started. How to generate a project:
- Install rails and pick a database.
- Run the following:
- rails yourapp
- script/generate scaffold ...
- script/server

To summarize practical thoughts on Ruby on Rails, this was a good session to understand the "hype" around Ruby on Rails. However, changing direction to complete projects in R on R rather than Java would require a much different set of skills. A tradeoff between less code and learning new skills would result. Plus, an understanding how a much more complicated project is written with R on R is still necessary. On the other hand, with Sun financing the JRuby language, and I think Microsoft funding Silverlight (need to confirm this), this is a language and framework worth following.