I will present at JFokus

A few weeks ago I noted that Sun in Sweden announced on the JavaForum meetup that they were going to have a full day Java conference in January. This conference is called JFokus and will have 4 different tracks with 4 speakers on each track. I will feature in one of these tracks, talking about testing Java code with JRuby and RSpec, and also how to build a DSL for doing database integration testing using Ruby. I believe it will be very interesting, and the rest of the day looks incredible nice too.

So, if you're in Sweden, Jan 30:th, look into it!

More information can be found at the official site: http://www.jfokus.se/.

Profile support in JRuby trunk

As noted a few posts ago, Sandbox has been ported and run in JRuby. You did need to use a special version, only available from a branch in the JRuby source tree. But now this support has been added to trunk. This means you can check out the latest version of JRuby trunk, gem install javasand, and everything will work.

For more info, see my previous post on this: here.

A Personal blog

Due to lots and lots and lots of stuff happening in my life right now, I haven't had the time to write anything substantial here in a while. Hopefully, this will change.

I have also decided to start a new blog, for more... personal musings. Books, music, movies. Stuff like that. Nothing that would interest the regular readers of this blog, probably. But anyway, here's the address: http://olabini.blogspot.com.

Ah, right: Have a merry christmas and a happy new year, everyone!

Another neat trick

Another sweet thing, that I've actually wondered idly about from time to time, is how you could get "provided?"-style parameters in Ruby. If you have used a language with this functionality, like Common Lisp for example, you know that this can be highly useful.

And just the other day, while reading Hal Fultons excellent (but poorly proof read) The Ruby Way (2nd ed) I found the way. Ergo, it looks like this:

def foo(bar, baz = (baz_provided=true; 42))
 p [bar,baz,baz_provided]
end

foo(13,47)
foo(13)
foo(13,42)

This will provide the output:

[13, 47, nil]
[13, 42, true]
[13, 42, nil]

which illustrates the usage pretty well. The magic, of course, lies in the fact that default parameters are evaluated, just the same as anything else. You could do some very crazy things inside that default value specification if you wanted. Anyway, just a nugget.

A very small Ruby method

I haven't had much time or inclination for blogging lately. Not much happening at the moment, actually. But I came up with one small thing I wanted to document. Just a practical thing for certain situations. Basically it's a with-method, that works fairly well. It's nothing magical and the trick is basic. It's more or less an alias, actually:

module Kernel
 def with(obj = nil, &block)
   (obj || self).instance_eval &block
 end
end

with("abc") do
 puts reverse
end

"abc".with do
 puts reverse
end

As you can see, insstance_eval can be used like JavaScript or VB's with. This is nice for the simple reason of documentation. I find this usage much easier to read and understand than most usages of instance_eval that I've seen.

So, that's it for today. I'll probably be back soon with some recent JRuby developments too.

The Curse of Camping: The story continued

It's time for another installment in the Camping saga. The last time I wrote about 1.5, and some things that didn't work properly in JRuby. This time, the announcement is once again this: Camping 1.5 works in JRuby. It works very well, actually. To show this, I will make it very easy for you to follow along in how to achieve it.

First, have JRuby installed, either from trunk or version 0.9.2 if that version has been released when you read this.

Secondly, gem install ActiveRecord, Camping and all their requirements.

Thirdly, gem install ActiveRecord-JDBC.

Fourth, put you MySQL JDBC driver on your classpath (or any other JDBC driver you care to use).

Download blog.rb from the Camping examples here. Modify it by adding the line

require 'jdbc_adapter'

after the other require's at the head of the file.

Finally, you need to create a database file, since JRuby doesn't support the standard choice of camping (which is SQLite3). To do this, create a file that's named (on Linux) $HOME/.campingrc, or on Win32 %APPDATA%/Campingrc. (%APPDATA% is on most Win32-boxes something like c:\Documents and Settings\olagus\Application Data). This file should contain your database definition in standard ActiveRecord fare. My example looks like this:

database:
 adapter: jdbc
 driver: com.mysql.jdbc.Driver
 url: jdbc:mysql://localhost:3306/blog
 username: blog
 password: blog

Of course, you should use your own individual settings and driver information.

Camping does only require that the database exists. It will add migrate the blog application automatically, and as soon as you've started the application by doing:

jruby $JRUBY_HOME/bin/camping blog.rb

it will listen on 3301 and be ready to serve an example blog application.

Have fun and enjoy!

Freaky freaky Sandbox has come to JRuby

I would like to announce the first release of JavaSand, which brings _why's spooky Sandbox to JRuby.

For those of you who hasn't played with Sandbox, it allows you to create a new area for executing Ruby where you have control on which classes are loaded and available. It's good for lots of things. It can be made very secure, for example. Or you can load several applications in different Sandboxes and they won't interfere with each other in any way.

Now, in MRI, this is done through some fairly involved swapping of symbol tables. In JRuby things are quite a lot easier. Actually, it's only a matter of loading the right classes and remove all methods not allowed.

So, how do you get to use sandbox from JRuby? First of all, you need a special JRuby, that can be checked out and compiled from svn://svn.codehaus.org/jruby/branches/sandbox. This functionality will come to regular JRuby to, but not until after 0.9.2 has been released. So, when you have this special version downloaded, you just install the RubyGem called javasand, and you're set to go. If you would like a fun example to try out, you can download sandbox_server directly from _why's code repository http://code.whytheluckystiff.net/svn/sandbox/trunk/bin/sandbox_server. To run it:

jruby -rubygems sandbox_server

and you can connect to your machine at port 5000, press enter, and you have an IRB session. Wow!

So, the project JavaSand is part of JRuby-extras and the source is in that repository, at RubyForge! Go ahead and test it now!