Ruby, Sequel and Trees

While working on some tree structure a couple of unit tests failed, when creating some form of summary of said tree structure. First of all here’s a condensed form of the code:

require 'sequel'

DB = Sequel.sqlite
DB.create_table :items do
  primary_key :id
  String :name
  String :foo, :default => 'NOT SET'
  Integer :item_id
end

class Item < Sequel::Model
  one_to_many :items
  def summary
    if items.empty?
      return [ { self.name => self.foo } ]
    else
      items.inject( [] ){ | r, sub_res | r << sub_res.summary }
    end
  end
end

r1 = Item.create :name => 'R1'
r2 = Item.create :name => 'R2'

r1.add_item r2
r2.foo = 'Ding'
#r2.save

[ r1, r2 ].each{ |i|
  puts "Item    : #{ i.id }"
  puts "Direct Foo: #{ i.foo.inspect }"
  puts "Summary   : #{ i.summary.inspect }"
  puts
}

Notice, that I’ve commented out saving r2. The output is:

Item    : 1
Direct Foo: "NOT SET"
Summary   : [[{"R2"=>"NOT SET"}]]

Item    : 2
Direct Foo: "Ding"
Summary   : [{"R2"=>"Ding"}]

What I didn’t expect – and why the unit tests failed – is the ‘NOT SET’ in the r1 summary.

One way to end up with what I originally expected is to save r2. Another way is to set r2.foo before adding r1 to r1:

r2.foo = 'Ding'
r1.add_item r2

How ever I’m still not sure whether this is intended behaviour and why it should behave like this. (If it is, I’d like to know why.)
What do you think?

Sinatra and reloading

Since its 0.9.2 release on 18th of May 2009, Sinatra doesn’t automatically reload files anymore – not even in development mode.

To achieve this use ’shotgun’

sudo gem install shotgun

and then start the server using:

shotgun <your_applicationname>.rb

The effect is essentially the same (apart from avoiding the issues the ‘traditional’ way of reloading apparently had – which is why it was removed). 

Thanks for pointing this out in this thread @ rubyforen.de.

A Pure Ruby Readline

 

As found on Github via RubyCorner on DEV_MEM.dump_to(:blog) – Multimedia systems blog.

For all of those who a running Ruby on a Windows machine (known not to be the ideal place to use the readline library) or on some flavour of Unix (where the library might not be available, at least not from scratch), there is now a pure Ruby implementation available: The pure Ruby readline on Github.

Euruko 2009 – back from Barcelona

These two days with Ruby enthusiasts form all over the world not just Europe was great. Nicely located at citilab, with very good public transportation to the city centre of Barcelona, there was enough space inside as well as out side the building to talk to the other attendees, just relax in the sun or work with the notebook. Two wi-fi networks inside and outside the building could deal well with all the notebooks and mobile phones connected to it. This worked very good indeed.

The presentations I liked most where the ones introducing really exciting and new stuff. First and foremost there’s Rhodes, which enables the creation of native mobile applications with Ruby and HTML. And of course Matz’ keynote was very entertaining as well. More really new stuff was about Adhearsion a way to build voice enabled application with Ruby (and Rails). Then some of the presentations were a really good show. Most notably Javier’s talk about gosu, a framework for games and Pablo’s presentation about Archaeopteryx which was probably the loudest presentation I’ve ever heard.

The only thing that was a tad bit disturbing for me was that I didn’t have one of the mobile microphones available and was kind of stuck behind the table as well as the phones themselves, as they seemed to go silent now and then. Aslak dealt with this best I think, repeatedly saying “Hello?” directly into the microphone whenever it went silent.

I think this year was the first time Twitter was heavily used during Euruko, reusing a bot made for Scotland on Rails. and this helped enhancing the communication and connecting people even more than in previous years. A special “Thank you” to all for the other attendees who gave me direct feedback about the presentation as well as the corresponding discussion about it, including but not limited to: Andrew Miller, Tim Becker, Mike Just, Dave Frey. Thanks a lot, indeed.

More summaries are available from Javier and Tomasz. 

Next year Euruko will take place in Krakow, Poland and I’m already looking forward to going there.

Euruko 2009

Over at euruko.org the registration is now open. The conference is on the 9. & 10. of May 2009 in Barcelona, Spain. It seems they collected quite a few exciting talks – and mine.

Really looking forward to going there.

Ruby 1.9.1 & Installing It Parallel To 1.8

Ruby 1.9.1 has just been released.

And just as a reminder: Dave Thomas describes how to install and run Ruby 1.9 in parallel to 1.8 – as well has giving some information about what has changed.

Ruby And Rails In Munich

The Ruby & Rails people in Munich will meet on Thursday 13^th November 2008 19:00 (CET) at the traditional place, the “Augustiner am Dom”. It’s also entered to the Ruby on Rails UG Wiki. Also see the German rubyforen site.

Things We Do, But Shouldn’t

I regularly fire up the same applications: TextMate, a browser or two, mail programs, iTunes, a shell, irb and others. Now, while Quicksilver is excellent for firing up applications (and a lot of other things), I’d still be busy typing and/or mouse-pointing and clicking. And doing that is boring, cumbersome and not what I like to do anyway. I shouldn’t (have to) do it. And, in fact, I don’t. A little bit of Ruby code will do it:

#!/usr/bin/ruby
%w( <full_application_paths_go_here> ).each{ | app | system "open #{app} &" }

Replace <full_application_paths_go_here> with a list of space-delimited full application paths, save it into a file (in ~/bin presumably), make it executable and there you go. Actually, the language doesn’t matter at all here. The only thing that does matter is to fire up the applications.

Starting all most used applications is now just a few key strokes away. There’s certainly a very similar way to do this on other *nix OSes and Windows.

Citation of the Day

In his keynote this morning David Heinemeier-Hansson described legacy software as ‘a thing of the past, we don’t like’. For now that’s my favourite quotation of this RailsConfEurope.

Other than that: Roderick van Domburg of Nedforce gave interesting hints at a metric reporting tool for Rails and Saikuro, a cyclomatic complexity analyzer written in Ruby.

Rails Time Again

A year has passed and it’s Rails time again: I’ll be at RailsConf Europe in Berlin next week. Actually I’ll be in Berlin on Sunday already. So if any of you Rails and Ruby folks likes to have a beer or something, just drop me an e-mail.

Ruby in Munich

It’s time for a new Ruby (and Rails) meeting in Munich. We’ll meet on Wednesday 9th of April starting at 19:00 (CEST) in the Pizzeria Michelangelo.

If youre’ coming, please answer via e-mail or comment by Tuesday (08.04.2008) 12:00 CEST (in order to make a reservation for enough tables). 

Possible topics are: A short report from Euruko2008 which happened in Prague in late March, actually any other Ruby related topics.

Euruko 2008

Euruko 2008 is in Prague this year. Here’s the Euruko 2008 website where you can register, submit a proposal for a talk etc. Matz will be there. And of course a few other guys. Including me  

One week with Leopard

The (at the time of this writing) new Mac OS X 10.5 Leopard is now installed on my MacBook for a week. Time enough to find the way through a few of the new features. Time Machine is of course an easy way for backing up the system.

Anyway, to me Spaces (virtual desktops) are a lot more important, since I missed this feature before. Of course there was VirtueDesktops (which even featured desktop switching via the motion sensors). However with Spaces you can assign an application to a certain Space.

Terminal now comes with tabs instead of many windows, which also helps keeping the desktops clean. And last but not least Mac OS X now also includes Subversion, Ruby and of course Ruby on Rails, including – but not limited to – gems and Rake.

Only issue: The background image of the login screen needs to be replaced. In case you also like another picture, LoginWindow Manager might be useful for you.

Euruko 2007 in Vienna, Austria

Wow, there are already 46 registrations for the European Ruby Conference, and 9 people who “might come”. That’s great, as we were already at the capacity for the room with that number last year. Obviously Ruby gained quite a bit of interest within the last year. Apparently it was a Good Thing to have a larger room this year: The room can take 100 people “easily” and 170 “squeezed in” (hope I got the translation right).

Currently there are already 19 people willing to give at least one talk, some even offered giving two. So there’s no problem filing to full days with interesting stuff about what’s going on in the Ruby world. I really looking forward to this, especially the Koichi’s talk about YARV and Ruby 1.9.1. How exciting is that? And then there’s something about Ragel, a state machine compiler. And, doing test automation myself, of course I’m interested in the talks about automation. These are going to be exciting days.

All that for a conference fee of just about 20 Euro.

Euruko – Location & Date

After a few weeks of struggling to find a location we finally found a place. In fact we also found a new date:

Euruko 2007 will be located in Vienna, Austria on Saturday & Sunday 10^th and 11^th November 2007.

This was also announced on ruby-talk as well as the Euruko wiki … and a few other places.
If you’re planning to attend or to give a presentation, please use the wiki to register.

European Ruby Conference – Another Step

We’ve now set up a Basecamp. Contact me with any requests for a login, if you’re interested to help getting the conference organised.
And if you couldn’t remember a single additional login, why not letting us know by commenting here or sending me an e-mail?  May be you have an idea about a talk you’d like to hear or, dare I mention it, a presentation you’d like to give.

The EURUKO is not a commercial conference, it’s meant to follow the Open Source spirit: If you like to contribute – well – do it.

EURUKO 2007 – Take two

Summary form the EURUKO 2007 planning meeting:

1. Location: Very very likely to be Munich, Germany
2. Date: Very likely to be the 10./11. or 17./18. November 2007
3. Improved organisation compared to last year.
4. Ideas for keynotes, precise location and more.

Stay tuned for more later.