Vita Rara: A Life Uncommon -

Mark's [J]Ruby on Rails Notes

Mark — Wed, 20 Aug 2008 10:43:17 -0400

Using GoldSpike to run Ruby on Rails in Standalone Mode

When running Ruby on Rails in a war using the GoldSpike servlets and context-param jruby.standalone is set to true you will need to use the jruby-complete jar file. Rails requires Gems in order to boot strap. I found that using the jruby jar file caused Rails to fail in initializer.rb when it tried to require 'logger' which is included in the ActiveSupport gem.

Also be sure to copy your required gems into WEB-INF/gems.

[EDIT: Better yet use ruby gem install --install-dir WEB-INF/gems. ]

Model Auto Completer

Twitter: You've Added Meaning to My Life and Changed Me

Mark — Mon, 23 Jun 2008 10:18:28 -0400

This past weekend was an emotional roller coaster. It all started with a post on Twitter from Veronica:

Pass this around, if there's anyone you know that could be a liver donor to this little guy http://tinyurl.com/5zbtfu So sad.

I was checking my Twitter feed on my iPhone just before going to bed Friday night, after a long day of work and family. I read that tweet, followed the link, read the blog post about Wyatt's fight for life, put the phone on my night stand haunted. I couldn't get it out of my head. I couldn't pick up my phone and continue my life as I had before reading that tweet. I'm a new father, and I could only imagine being in the same situation and crying out for help. Echoing in my head was:

And whoever saves a life, it is considered as if he saved an entire world."

Oh Twitter... How Thou Hast Ruined Me

Mark — Thu, 12 Jun 2008 00:34:17 -0400

Sylva looked at my blog and pointed out I haven't posted in about two months. Since getting on Twitter and really starting to use it my blogging has evaporated. I didn't blog a lot before Twitter, but since Twitter I almost never blog.

So, what is it about Twitter that is so compelling for me? It's short. Posting is fast with Twhirl. I think well in short bursts. I don't feel compelled to develop a deeply thought out, well composed and edited blog post. In the past I've spent hours and hours writing blog posts on technical subjects. It takes a lot of time to get them right. Twitter is just so immediate.

It's a Boy: Ezra Isaac - April 7, 2008

Mark — Wed, 9 Apr 2008 09:52:36 -0400

Monday afternoon Ezra Isaac entered the world. My lovely wife Sylva did an amazing job. Ezra was born at home. Truly an amazing experience.

How I Got Over "import java.util.*;"

Mark — Tue, 11 Mar 2008 14:43:35 -0400

It's taken me years, but I finally got over import java.util.*;. First, I don't use an IDE. I know an IDE could manage my imports, but I'm not an IDE guy. So, for years I've managed my imports manually, or given up and done import java.util.* and felt guilty about it. Well, I'm over that, and I can give Groovy the credit. By default Groovy imports java.util.*. I've been using Groovy every day now for about a year and a half and the house is still standing, our code compiles, we haven't had name conflicts. Things work, and it's a lot easier.

I used to worry about name clashes and compilation speed, and other shiboleths spoken of around coder camp fires and in hushed tones. After all everyone "knows" that the * should be avoided. Well, I'm over it, import java.util.* is just fine with me. Now when I start a Java source file I almost always just add java.util.*.

Using Dynamic Method Invocation to "Script" Java

Mark — Tue, 26 Feb 2008 00:03:56 -0500

Although Java isn't thought of as a dynamic language now a days, what with Ruby and Groovy being all the rage, Java does have support for dynamic features. (See my previous blog post on the subject and the solution I came up with.)

A Use Case for Dynamic Java

Currently I'm wrapping about a hundred EJB 2.1 LocalHome classes in DAO's, and having them transform local EJB entities into POJO's. Much of the code is largely boiler plate. Actually it's mind numbingly boiler plate. Here's a sample of wrapping a finder:

What's Wrong with Java's Dynamic Dispatch or "How I Implemented sendMessage()"

Mark — Mon, 25 Feb 2008 23:33:24 -0500

(Related article using this technique to "script" some Java objects: article.)

The following code quickly illustrates an issue with the Reflection API's in the Java language. At run time finding methods on classes requires that the types passed to Class#findMethod() exactly match those found in the method declaration. The JavaDoc and language spec refers to these as the "formal parameter types".

The issue is, I have a method that takes an A, and I have an object of B that extends A. If you run the following code it will fail, being unable to find the method.

Closures and Bindings in Groovy

Mark — Fri, 8 Feb 2008 13:06:57 -0500

You can learn something every day. That's what is so nice about being a software developer.

Today I was looking at some Grails code, seeing how some of the metaprogramming features of Groovy are used in the framework. After poking around I decided to look at the ServicesGrailsPlugin to see how the automatic wiring of services was done, and ran across the following code:

def doWithSpring = {
  application.serviceClasses.each { serviceClass ->
      def scope = serviceClass.getPropertyValue("scope")

    "${serviceClass.fullName}ServiceClass"(MethodInvokingFactoryBean) {
      targetObject = ref("grailsApplication", true)read more

Yes the JVM is a Multi-Language Platform

Mark — Thu, 7 Feb 2008 11:52:50 -0500

Although talk about multiple languages running on the JVM has grown over the past few years, the reality of it really hit home with me this morning. I turned to one of my employees who has been doing JVM development for me since April of last year. The interesting thing is probably 95% of the JVM work he has done isn't in Java, it's in Groovy. Here's to the multi-language Java platform and a thank you to those developers who are making it a reality.

Ruby Metaprogramming: Declaratively Adding Methods to a Class

Mark — Sun, 27 Jan 2008 22:36:01 -0500

In this brief piece I will examine Ruby's support for metaprogramming and how to define class level methods that add instance methods to our class implementations at run time.

Over the past few months I've been learning Ruby on Rails. One of the most attractive features of Rails its declarative style of defining relationships and validations on models; and filters on actions.

A simple example of this declarative style:

class Party < ActiveRecord::Base
  has_many :addresses
end

This class defines a Party model that can have many addresses. The simple "has_many :addresses" declaration is a great example of the power of Ruby. This simple statement adds a number of methods to our Party class, and allows us to easily manage relationships between our parties and their addresses.