Top-down and Bottom-up programming illustrated by Mac OS X and Windows

Bottom-up programming starts by developing the data model before designing the user interface. Windows Start/Programs menu illustrates this approach. Since programs shortcuts are stored in the directory Programs the menu displays the content of this directory.

Windows XP Start menu

Top-down programming starts by designing the user interface before developing the data model. Mac OS X dock illustrates this approach. As it should be easy for a user to launch an application the dock displays big icons accessible in one click.

Mac OS X Dock

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Back to VIM for Ruby and Rails

I learned to use VIM at the university to administrate linux systems and to develop C++ apps. Then I moved to Java and I enjoyed using an IDE like Netbeans. When I started to play with Ruby and Rails I kept using Netbeans as my editor of choice as it plays very well with them.

As I was bored with “Up arrow key, End key, Enter key” instead of “O” to insert a new line above my cursor and I wanted to play again with this so old but still alive editor, I installed the plugins: rails.vim (just great), haml syntax highlight (I ♡ haml) and irblack color scheme (more Textmate like).

With rails.vim, you get just great shortcuts to browse your rails source file. Type :Rmodel your_model_name to edit your model source file — :Rcontroller, :Rview, :Rmigration, :Rjavascript, :Rstylesheet… work too! It also includes :A (jump to alternate file) and :R (jump to relative file) commands. :A switches between source code and corresponding spec file, :R jumps from model to migration file. The most amazing combo: :AV to open up the alternative file (your spec file usually) in a vertical split window.

I finish up with the two commands I learned to use and love.1) Type ma to “mark” your cursor position as ‘a’ then type 'a to get back to this position. 2) Use qa to record a macro in ‘a’, press q again to stop recording. Then @a to replay it. Using commands to jump to next word / end of line / next something character it can be much faster than making a substitution using regexp or so.

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How-to make the front mic working on Ubuntu 9.10 (Dell laptop: Intel Hda soundcard)

Ubuntu 9.10 comes with alsa 1.0.20 allowing the front mic to work on a Dell XPS M1530. From the Sound Preferences, select Microphone 2 then fire up a terminal, launch alsamixer -V capture and set the following options and enjoy!


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Ruby 1.9 faster than Ruby 1.8?

Today I ran the following script with Ruby 1.8 & Ruby 1.9 to compare their performances:

def bench
  start =
  1000000.times do
  puts - start

puts "Test 1: do things"
bench {
  i ||= 1
  i = i + 1 

puts "Test 2: \"stuff\""
bench {

puts "Test 3: 'stuff'"
bench {

puts "Test 4: :stuff"
bench {

Ruby 1.9 performances are promising:


Ruby 1.8 (sec)

Ruby 1.9 (sec)

Perf Increase
Test 1: do things



Test 2: "stuff"



Test 3: 'stuff'



Test 4: :stuff




So Ruby 1.9 is 3 to 5 times faster than Ruby 1.8 to run simple operations. I then checked with a small Rails app.

Once I got rubygem installed for Ruby 1.9, the gems I needed installed for Ruby 1.9, the plug-ins I use patched for Ruby 1.9, and my ruby code patched for Ruby 1.9, – yes, it was painful! – I fired: time spec spec

Ruby 1.8

$> time spec spec

Finished in 0.594813 seconds

44 examples, 0 failures
spec spec  2.49s user 0.79s system 93% cpu 3.522 total

Ruby 1.9

$> time spec spec

Finished in 0.625589223 seconds

44 examples, 0 failures
spec spec  8.74s user 0.32s system 93% cpu 9.648 total

Grrrr. Ruby 1.8 & 1.9 both pass the specs in ~0.60 second but Ruby 1.9 takes 8.74 seconds in total vs 2.49 seconds for Ruby 1.8. The same behavior occurs when running a Webrick server via script/server: Ruby 1.9 is 2 times slower than Ruby 1.8 to boot up the server and it handles the requests just as fast as Ruby 1.8.

Any Ruby guru to explain such deceiving results?

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How-to fix low volume on Ubuntu (Dell laptop: Intel Hda soundcard)

It took me a while to find a way to fix it as all the alsa-mixers where set at 100%. The solution: run alsamixer -D hw:0 to display a new mixer called “Front” set at 70% by default – shift it to 100% and you can now listen to music or watch a film at a comfortable level!
Ps: If anyone knows how to increase the internal mic input volume and/or make the front mic work on an Dell XPS M1530: I’m definitely interested!

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New rails plugin to find unused translations

A small while ago, I released with @lboix a simple rails plug-in that displays translations stored in your locale file but not called from your source code. It is called unused_translations and it is available on GitHub. I hope you’ll enjoy it!

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Make acts_as_versioned create new version on demand

I use acts_as_versioned to manage versions of Rails models. As I don’t want to create a new version of my document everytime I save it (to fix a typo for instance), I added a virtual attribute called save_with_revision to my model and put it into the definition of version_condition_met?.

attr_accessor :save_with_revision

def version_condition_met?
  @save_with_revision.to_s[/true|1/] != nil

Cool… except that it does not save intermediate updates into the **_versions table. Let say you create document version 1.0, then update it without creating a new version (from v1.1 to v1.4) and finally save a new version (v2.0); v1 will still be v1.0 and not v1.4.

To save intermediate updates into the **_versions table, just add to your model:

def after_update
  if !version_condition_met? && changed?

Hope it helps. :)
Anyone with a better solution?

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File versioning in Ruby on Rails with Paperclip & acts_as_versioned

This short tutorial shows you how to manage file versioning in Ruby on Rails by making Paperclip falling in love with acts_as_versioned. Paperclip & acts_as_versioned are plug-ins for Ruby on Rails: Paperclip manages file upload, acts_as_versioned enables models versioning.

Patch Paperclip

I patched Paperclip to keep old files when a new revision is saved. A fork of Paperclip adding the option keep_old_files to make Paperclip working with acts_as_versioned is available here: You can install it running:

script/plugin install pcreux_paperclip

Update your Paperclip + acts_as_versioned model

Just three things to do:

  1. update the url & path to store your files by ‘version’
  2. set the option keep_old_files to true when a new version get saved
  3. add the interpolation of :version
class Document < ActiveRecord::Base
  has_attached_file :attachment,
                    :url => "/system/attachments/:id/:version/:style/:basename.:extension",
                    :path => ":rails_root/public/system/attachments/:id/:version/:style/:basename.:extension",
                    :keep_old_files => :version_condition_met?
  Paperclip.interpolates :version do |attachement, style|

I hope it helps. :)

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Behavior Driven Development in a nutshell

A good development practice is to use automated tests to ensure the application works well and to facilitate refactoring. It is even better to write these unit tests before writing the code: this practice is called Test Driven Development (TDD) and it is a great way to check that the code is what it is excepted to be. Behavior Driven Development (BDD) goes a step further as you write specifications describing what the code does.

Behavior Driven Development is more about interactions with the application than just unit testing. It forces the developer to understand the responsibility of the method he is about to write. Using good tools, the specs written to test the application can be used as specifications.

Ruby BDD frameworks

RSpec is famous ruby BDD framework that plays with contexts and assertions. It is mainly used to describe the behavior of application code in specific contexts.

describe Calculator do
  context "switched on" do
    before(:all) do
      @calc =!

    it "should have a result equal to 0" do
      @calc.result.should equal(0)

These specifications are a good documentation for developers as they focus on the application code. Since BDD encourages collaboration between developers & non-technical participants, we need a tool describing the application at a higher level: Cucumber, to the rescue!

Cucumber permits to describe how the application should behave via user stories written down in a business-readable language. A scenario looks like that:

Given I am on the messages page
When I fill in new_message with "Hello"
  And I press "Send"
Then I should see "Message sent!"

These plain-text scenarios can be shared between developers and non-technical participants to validate the application behavior. Each step of this scenario is defined in Ruby to permits to run the scenario against the application and to generate a detailed development-status report.

BDD process

The focus of BDD is the language and interactions used in the process of software development. It implies outside-in development starting with User Interface definition to code development. Therefor, you create scenarios for the features you would like to develop and then follow the BDD process:

BDD process schema

  1. for each scenario describing a feature
  2. run the scenario – it fails (go red)
  3. define the first step – go red
  4. write down the application code getting the step to pass – go green
  5. refactor the code and repeat steps 4 & 5 for each step until…
  6. the scenario passes – go green
  7. refactor the application code

Once your done, you can move on to the next feature. :)

These scenarios drive the developer into the development process. It forces him to focus on writing down the test or application code to get the current step to pass, before moving on to the next step. The developer is also gratified every time a step passes and he knows with precision which features work.

I use Behavior Driven Development to develop Ruby on Rails applications. I work with non-technical participants on Cucumber scenario and I can give easily generate a project development status that shows working / pending / not-working scenarios. When switching to “development mode”, I just focus on getting the next step to pass – my mind is free of thoughts concerning the feature definition & application requirements. I usually get a step to pass in a couple of minute and everytime it occurs, it am gratified of seeing it going green. Finally, the refactor process occuring everytime a step or a scenario pass, the application design is constantly evolving to fit just the requirements: that is emergent design.

Many developers I talked with say that it is hard to write tests before writing the code. I think it is just hard to switch to this method. Try it and the coding process will look easier and your code will get better – just because you will specify before coding instead of doing both at the same time.

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Rubular — Regular expressions editing & testing made easy

If you use to spend ages building and testing regular expressions, you might be interested in the online expression editor Rubular. Rubular is a handy way to test ruby-based regular expressions as you write them.


Since the regular expression flavor used in Ruby is “Perl Style”, you can use this tool to test regular expressions written for PHP (preg function), Python, Javascript etc. Enjoy!

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  • Hi, my name is Philippe Creux.

    This blog is about Agile project management, Ruby programming and other cool things. I haven't published anything here since 2011. Find the latest and greatest on!