Embrace Uncertainty

It was interesting.

"Embrace Uncertainty"

Merb will be merged into Ruby on Rails 3

Merb gets merged into Rails 3!

Merb Will Be Merged Into Rails 3.0

Malcolm Gladwell's articles

Someone gave me the links to interesting articles by Malcolm Gladwell.

All of them were very interesting.
But I list them in the order of the one that made me feel like putting on this blog the most to the one the least.

Million-Dollar Murray (Why problems like homelessness may be easier to solve than to manage.)

What we can learn from spaghetti sauce

The Uses of Adversity

The reason why I wanted to put the first one in this blog was the last section about air pollution. That gave me a new perspective and made me realize that by retrospective, in the past, I have observed a similar phenomenon.

The part of the second article, actually a talk, "people don't know what they want" is related to how we develop software in Agile way. It is based on a notion that the users don't know what they want. So we build software incrementally, showing it to the users as we go and deciding what to do next based on their reactions. That's all I wanted to say in this blog. The main theme of the talk is much beyond that, however, and that will heavily influence the way I view things from now on.

The third one gave me a new important perspective as well. I'm glad that I read it. But most probably it would have stayed as a bookmark instead of putting it in this blog if I didn't get its link with the other two.

Reflection on my life, of the result of the presidential election in United States

I felt the enthusiasm of the people while I was following the presidential election in United States last night.

I view Barack Obama as a human and his being a black person doesn't come to my mind. And following the election yesterday and listening to his speech after he became the next president of the United States, I felt that the people chose a person with a positive choice, not a compromise of choosing a person less evil than the other.

Despite of these facts, while I was in the bed afterward, I was reminded of my high school English class.

It was in a small city in a rather rural area of Japan and the majority of the people there spend their entire lives never seeing any foreigner and only speaking their dialect even only speaking the standard Japanese only occasionally. While I was a student very aware of human rights and social issues, those issues rarely came to people's mind.

One day, in one of the English classes, the teacher played a tape of Martin Luther Kings Jr.'s speech, "I have a dream". And he had a sincere conscience.

I am very graceful that he played the speech.

Quick note about Workling

I have found that when using Starling, setting "Workling::Remote.dispatcher = Workling::Remote::Runners::StarlingRunner.new" in environment.rb is not necessary because Workling checks the existence of Starling before any other gems or plugins such as Spawn.

I've found this by looking at the code vendor/plugins/workling/lib/workling.rb, self.default_runner, which was a point of failure at one execution.

self.default_runner takes care of setting it automatically.

The problem was that when it is set in environment.rb or even only in environments/development.rb, "rake spec" fails reading the setting for development environment in config/starling.yml. (Even when I explicitly set ENV["RAILS_ENV"] = "test".)

If another background process gem or plugin is used such as Spawn while Starling gem is still installed, Starling is still picked up. I think we can specify Spawn in environment.rb.

Or it would be ideal if only one background process gem/plugin installed out of Starling, Spawn, and Backgroundjob.

Election

I just write this quickly.

I have always been a supporter of proportional representation (I think that's what's called in English. I'm writing this quickly so I'm not verifying it because I'm extremely busy these days.).

By that way, the seats for the legislative (such as parliament) are allocated based on the percentage of the votes each party gets.

First of all, every vote counts.

Second, these days in much modern society, geographic location doesn't say much. People living in geographically distant places share the same opinion and concerns. People living in the same location don't share anything in common. That's common. Majority of the people live where they live because they found an apartment or a house there. Could have been just any other place. In a few kilometers apart, in one electoral district, the party you voted for wins and in another district, another party wins. Is there anything different between two districts? Not really.

If keeping representative from each district is important, at least have two houses in the parliament. One consists of the members of parliament elected from electoral districts and the other consists of the members of parliament elected by proportional representation.

I know many countries have been using proportional representation for a long time. So writing this blog entry doesn't mean to criticize anything anywhere. I'm just writing this to say that I'm supporting proportional representation. Also specifying any country doesn't go well with my blog's underlying philosophy of keeping it geographically neutral. (My blog is only for expressing my opinions or informing what I found.)

I will try to find a time in the future to elaborate this more, using more correct words. But I think the readers can get an idea by replacing words appropriately such as "member of parliament" to "senator", etc. Right now, I just wrote it very quickly because I don't have a time.

Basics of fundamentals

It is pathetic that I have to even write this in my blog.
And I have been certainly assuming that any reader of this blog understands this.
What I wrote in the past reflects it.

Here, I write it using simplest possible words.

--- Explanation that explains most what is observed is what is accepted.

-> There is an observed behaviour or phenomenon or artifact that exists. In order to explain it - why it happens or why it exists -, there is a theory. The theory that explains the behaviour or the phenomenon or the artifact best is what is widely accepted to be true. There is a verification process to back it up, often using statistics.

-> The main reason why there are many people who don't believe in religion is that what religion says conflict with what is observed. Simply being ignorant with what is observed or the facts doesn't justify that what a religion says is correct.

--- Separation of public affairs and religion.

-> It is essential and fundamental that politics and education are separate from religion. Any one religion shouldn't control or influence politics and education. It is essential in order to keep the civilization functional for all the human beings.

-> By knowing why and how a certain religion spread in a certain part of the world in the course of human history, we know that there is no reason why one religion should be allowed to control other people.

--- Basic human rights.

-> Nobody has a right to be over anybody else based on his/her belief. Every human being is equal and believing a certain religion doesn't give a person to be superior to other people.

-> Nobody should be discriminated based on his/her belief.

In addition to the above, I write some more regarding what I observed today at a public language school today.

--- Religion is created by human being as a part of its history.

-> Over the course of human activities in different regions of the world, a certain beliefs emerged with an influence from the environment where the people in the region were surrounded.

--- Religion was often spread for political reasons and what it says was often created because of the political reason as a part of human history.

--- It is not true that all the religions have a god.

--- It is not true that all the religions believe in the same god.

-> Many religions have multiple gods and the idea of the unique god is actually a minority. The reason why that idea is so well-known is that the group of people who believed in it conquered other parts of the world with force, military power, discrimination, and manipulations. For example, The majority of North and South America were conquered by military power and it was injustice. And early 20th century, the majority of the world was colonies of European countries. Simply conquering other countries doesn't justify that the god of conqueror's religion is same as the ones of other religions.

-> Many religions don't accept a notion that all the religions believe in the same god. It's simply a cultural insult. The culture is influenced by the environment where the people live in and there is no justification that a person in one culture says that his/her culture is better than the other.

At the end, I just write some of my opinions.

--- Believing in a religion doesn't make a person morally better.

-> It only gives an illusion to the person that he/she is superior.

After writing this, I still think that it's pathetic and sad that I have to even write this. I thought that these days, everybody understood human rights and democracy and that everybody understood basic human history.

Awareness of recycling

Yesterday, I had a chance to bring awareness of recycling without causing other people defensive.
But I missed the chance.
I regret it very much.

At a language course I'm taking, the teacher asked me what I never do as a part of an exercise to explain it in the language we are learning.
I could have said that I never throw metal cans in the garbage because it's important to recycle them.

I have been noticing that many students there are throwing them in the garbage can instead of in the box for recycling metal cans, probably because majority of the students are immigrants and they are not aware of the importance of recycling.
That bothers me a lot.

One day, I mentioned to one student that there is a box for recycling metal cans. She was very upset taking it as an accusation.
Because the box for recycling them is not located in that floor and it's only on the first floor, I made a proposal to the school to put one in each floor at least to make it easier for the students to recycle metal cans.

The school seems to be doing the best to recycle materials as much as they can.
With the constrain that the company working for them who collects papers collects only papers in the recycling bin in each class room enforcing us to put only papers in the recycling box and that the company working for them who collects metal cans only collects them from the box in downstairs, I noticed that a cleaning person picks metal cans from the garbage cans and separate them for recycling.
I appreciate the cleaning person's work very much.

At the same time, what I concern most is that those students recycle in other part of their lives outside the school settings. If they continue to throw recycling materials in the garbage, it is a huge amount of recycling materials thrown away, which is not good for environment.

So I want them to have an awareness of the importance of recycling.
And yesterday presented me a good chance to initiate to achieve it.
I hope there will be another chance.

Setting up GIT public repository

I found setting up GIT public repository by copying the Rail application to the origin server doesn't allow tags to be pushed.

This lists the steps I took to set up GIT public repository that allows tags (or all GIT objects, I think) to be pushed.

1. Create bare GIT repository from the Rails app I want to create a repository for.

$ git clone --bare rails_app rails_app.git

2. Make the repository to be sharable by GIT daemon just in case I want to do so.

$ touch rails_app.git/git-daemon-export-ok

3. Tar it and scp to the server where I want to have the public repository, which becomes the origin server.

$ tar cvfjp rails_app.git.tar.bz2 rails_app.git

$ scp rails_app.git.tar.bz2 @:~

4. In the origin server, add a new user called "git".

$ sudo adduser git

5. Change the shell for "git" to git-shell.

$ sudo vim /etc/passwd

git:x:1001:1001:,,,:/home/git:/usr/bin/git-shell

6. In the origin server, create git directory under /var.

$ sudo mkdir git

$ cd git

7. Untar the tar file.

$ sudo tar xvfjp ~/rails_app.git.tar.bz2

8. Change the owner of "git" directory to "git".

$ cd ..

$ sudo chown -R git:git git

Installing RMagick Ruby gem

Just for a record (because I forgot how when I had to do it again on another server):

* On Ubuntu Hardy:

   1. Install ImageMagick. 

      $ sudo aptitude install libmagick9-dev

      $ sudo aptitude install imagemagick

   2. Install RMagick gem. 

      $ sudo gem install rmagick

* On Mac OS X Leopard (with MacPort):

   1. Install ImageMagick. 

      $ sudo port install ImageMagick

   2. Install RMagick gem. 

      $ sudo gem install rmagick

RubyGems 1.2.0 is released

Just yesterday.
(Announce: RubyGems Release 1.2.0)

Get it by:

wget http://rubyforge.org/frs/download.php/38646/rubygems-1.2.0.tgz

The Wisdom of Crowds

There was an occasion that I mentioned "The Wisdom of Crowds" responding to the other person during a conversation today. I promised him to send a link to it. And this is what I found instead of just sending him a description in a bookstore site.

"The Wisdom of Crowds"

"Skinny Controller, Fat Model" best practice

My first impression about reading about it ("Skinny Controller, Fat Model") was that it is a basic of Object-Oriented Programming. If you are familiar with Object-Oriented Programming practices such as small method, refactoring, Design Patterns, your code naturally becomes what this article is proposing. Especially, my impression is that if you are doing Test/Behaviour-Driven Development, it is even difficult NOT to become as proposed.

What I liked about "Skinny Controller, Fat Model" is that it is explaining the best practice from the different perspective and with the simpler expression. You can reach the same code either following the basic Object-Oriented Programming practices or following "Skinny Controller, Fat Model".

Ultrasphinx setup part2

Regarding what I wrote about test database in section "4. Build index" in my previous post "Ultrasphinx setup", RSpec code would become like below.

I put this under spec/models accessing database. But for controller spec under spec/controllers, I mocked Ultrasphinx::Search so that the controller spec is not accessing database.

(Note: The line with "system(..)" is one line.
It is shown to be multiple lines because of the space.)

require File.dirname(__FILE__) + '/../spec_helper'

describe "Ultrasphinx sample" do
  fixtures :overviews

  before(:each) do
    system("cd #{RAILS_ROOT}; 
      rake ultrasphinx:index RAILS_ENV=\"test\"")
    system("cd #{RAILS_ROOT};
      rake ultrasphinx:daemon:start RAILS_ENV=\"test\"
        &> /dev/null")
  end

  after(:each) do
    system("cd #{RAILS_ROOT};
      rake ultrasphinx:daemon:stop RAILS_ENV=\"test\"
        &> /dev/null")
  end

  it "should find text with 'test'" do

    @search = Ultrasphinx::Search.new(:query => "test")
    @search.run

    @search.results.size.should == 2

  end

end

Ultrasphinx setup

It was more straightforward to figure it out than other things I have done in the past. But I just write the whole thing I did to set up Ultrasphinx.

1. Sphinx installation

$ wget http://www.sphinxsearch.com/downloads/sphinx-0.9.8-rc2.tar.gz

$ tar xvfzp sphinx-0.9.8-rc2.tar.gz

$ cd sphinx-0.9.8-rc2/

$ ./configure --prefix=/usr/local

$ make

$ sudo make install

2. Install Chronic
(Chronic is a natural language date/time parser written
in pure Ruby.)

$ sudo gem install chronic

3. Install Ultrasphinx plugin

$ cd RAILS_ROOT

$ svn export svn://rubyforge.org/var/svn/fauna/ultrasphinx
/trunk/vendor/plugins/ultrasphinx
(if GIT or other version control system is used.)

(Or if Subversion is used,
$ script/plugin install -x svn://rubyforge.org/var/svn/fauna/ultrasphinx
/trunk/vendor/plugins/ultrasphinx)

$ cp RAILS_ROOT/examples/default.base RAILS_ROOT/config/ultrasphinx/

Add is_indexed to the model: e.g.

class Overview 
  is_indexed :fields => [ 'title', 'description' ]
end

4. Build index

$ rake ultrasphinx:configure <= Generates development.conf

($ rake ultrasphinx:configure RAILS_ENV="test" <= Generates test.conf)

$ sudo ln -s /usr/local/mysql/lib /usr/local/mysql/lib/mysql
(Because "rake ultrasphinx:index" has an incorrect path "/usr/local/mysql/lib/mysql".
Otherwise, "rake ultrasphinx:index" fails.)

$ rake ultrasphinx:index <= For development database

($ rake ultrasphinx:index RAILS_ENV="test" <= For test database)
(Of course, in the Test::Unit or RSpec, test database is cleaned up every time so this has to be put inside Test or Spec.
i.e.
system("cd #{RAILS_ROOT}; rake ultrasphinx:index RAILS_ENV=\"test\"") )

5. Start/Stop daemon

$ rake ultrasphinx:daemon:start <= For development database

($ rake ultrasphinx:daemon:start RAILS_ENV="test" <= For test database)

- How to stop Ultrasphinx

$ rake ultrasphinx:daemon:stop

GIT

I have started using GIT recently. I like it very much.
In fact, within a day of starting using it, I switched all the current projects to it.

Git TextMate Bundle

Just for a record.

Git Bundle

Nginx and Ruby on Rails ssl_requirement

ssl_requirement plugin was causing infinitive loop.
It was because request.ssl? was always returning false in ensure_proper_protocol method inside SslRequirement.
Actually, request.ssl? method is checking the value of X-FORWARDED_PROTO.

So it turned out that you have to set X-FORWARDED_PROTO in Nginx's configuation file.
i.e.

server {
       location / {
                    proxy_set_header  X-FORWARDED_PROTO https;
       }
}

Growth hormone release in pulsatile pattern

I've just learned that the effect of growth hormone is bigger with the existence of the periods when it is not released. In that case the hormone release has a pattern of pulse.

Also I learned that it is more intertwined with other hormones than I had known before. But it makes sense.

Human body or any mammal's body is amazing in how it's functioning. On the way back home, I was looking at other people on the bus and thought that at each moment, inside their body, hormones and other chemicals are highly balanced. Of course, it has been one of the reasons why I respect each individual human and creature. I was reminded of that feeling strongly again today. I just wish all the individuals can achieve the best they can achieve.

Great Team Basketball

In NCAA Men's basketball tournament, Davidson University played great team basketball games. I just loved the way they played basketball.

Healthy snowboarding brand

After an "Event to build entrepreneurial software in 48 hours over a weekend", I got into a mindset to come up with a new brand a little bit.

That led me to come up with a way of snowboarding in a healthy athletic way.

Often times, many snowboarders are rude and aggressive and do stuff like smoking and drinking excessively.

But if you take snowboarding itself, it's a good sport requires whole body muscles. It has variety of movements - free riding, free styling in snow park, etc. It's challenging, which gives you positive attitude overcoming fear. It's outdoor, often breathing fresh air in the mountains. And on the top of the ski hills, you can see magnificent views, which refreshes your mind.

So I would package all these good features together and brand it as a healthy snowboarding. The image of that brand is like working out in the gym. You eat well with nutritious food and in the daily life, work out and tone up the muscles, in order to give you the best snowboarding performance. A friendly attitude toward other people has the high value. And you progressively improve various snowboarding skills, including free style moves.

Possibility of hydrogen production for hydrogen vehicle

After I wrote a blog entry, "Wind-powered generator on the top of the ski hills - Éoliennes sur le sommet des centres de ski", I was reminded that I live in a place with abundant electricity by hydroelectric energy production.

Then I thought of hydrogen vehicles. As far as I remember Iceland is the only country that can produce hydrogen from water by electrolysis using clean natural energy source, enough to support almost all the vehicles in the country. Maybe we can be next. With the combination with the electricity by wind-powered generator, maybe we have enough electricity needed to produce hydrogen.

REST for various scenarios

The purpose of the article is different but I read it in such a way to learn more about REST.

"Addressing Doubts about REST"

Also the comments are interesting.
And one of them "Resource transformations" is what I'm concerned with most now.

How to set up to access LDAP from Ruby on Rails

Note: This is for Mac OS X 10.5 Leopard. For other system, change the directory path appropriately.

1. Install OpenLDAP.

 1-1. Install Berkeley DB.
   (OpenLDAP requires this.)

   1-1-1. Download the source. db-4.5.20.tar.gz
     (OpenLDAP only works with the version up to 4.5.
      Don't download 4.6.)
     ("Berkeley DB 4.5.20.tar.gz, with AES encryption(8.9M)"
      in
      http://www.oracle.com/technology/software
      /products/berkeley-db/db/index.html)

   1-1-2. Unpack the tar.gz file. And build it.
     $ cd build_unix
     $ ../dist/make

   1-1-3. Install it.
     $ sudo make install

 1-2. Install OpenLDAP

   1-2-1. Set the environment variables.
     (See the message with "configure --help")            
     $ export CPPFLAGS="-I/usr/local/include"
     $ export LDFLAGS="-L/usr/local/lib"
     $ export LDFLAGS="-L/usr/local/BerkeleyDB.4.5/lib/"
     $ export CPPFLAGS="-I/usr/local/BerkeleyDB.4.5/include/"

   1-2-2. Build it.
     $ make depend
     $ sudo make
     (make has to be executed as root
      otherwise a permission error occurs.)

   1-2-3. Install it.
     $ sudo make install

   1-2-4. See doc/guide/admin/guide.html for how to use it.
     Especially, "2. A Quick-Start Guide".            

     e.g How to start it.
         $ su root -c /usr/local/libexec/slapd

2. Install ruby-activeldap Rails Plugin.
 (http://code.google.com/p/ruby-activeldap/)
 $ script/plugin install \
   http://ruby-activeldap.googlecode.com \
   /svn/trunk/rails/plugin/active_ldap

3. Install activeldap Ruby Gem.
 (ruby-activeldap Rails Plugin only generates
  scaffold model to access this gem.)

 $ sudo gem install activeldap

4. Install Ruby/LDAP.
 (activeldap is a wrapper for this.)

 4-1. Download the source. ruby-ldap-0.9.7.tar.gz
   (http://sourceforge.net/projects/ruby-ldap/)

 4-2. Unpack the tar.gz file. And build it.
   (See README file under the unpacked directory.)
   $ ruby extconf.rb --with-openldap2
   $ make

 4-3. Install it.
   $ sudo make install
   (It's installed under /Library/Ruby/Site/1.8)

Event to build entrepreneurial software in 48 hours over a weekend

Over the last weekend, I participated in an event to build software product in two days and present it to investors at the end.

My goal of participating the event was to work on Ruby on Rails development and to get familiar with local start-up scene because they are the ones who are using Ruby on Rails most.

Our team lead was very professional in skills, knowledge and the manner he conducted business throughout the project. I was able to enjoy the development fully.

During the event, series of experts in business, entrepreneurship, and technology visited each team and gave us advices. It was very interesting to see how the project was being shaped as a result of this interaction and how the direction changed along the way.

The presentations by investors and accounting professional, etc. at the beginning of the event were very informative also. And I was able to meet various technical people during the event.

My goal was more than fulfilled.

Article about Reality Driven Development

"Pragmatic is the new black - Reality Driven Development"

There is some truth in it.

RSpec Stories resources

I just put it in here because I refer to it often.

RSpec Stories resources.

By the way, one comment in David Chelimsky's blog entry in there has a link to a Story Editor using Prototype.

Éoliennes sur le sommet des centres de ski

Since I'm learning French, I try to write a blog entry in French as well.
This is about the idea of Wind-powered generator on the top of the ski hills, which I wrote on February 5th. Please correct it if you are familiar with French. My French is not good yet:

J'ai une idée de mettre des vent générateurs sur le sommet des centres de ski parce que souvent il vente très fort là. L'électrcité générée est utilizé pour l'ascenseurs.
(Corrigez les erreurs, SVP. Ça ne fait pas longtemps que j'apprends français.)

---

Mon ami a corrigé les fautes (Merci!):

J'ai eu une idée d'installer des éoliennes sur le somment des centres de ski car il vente très fort a ces endroits. L'électricité générée serait utilisées pour les remonte pente.

RSpec Stories

I like RSpec's new feature, RSpec Stories.
In the past, I saw Acceptance Test Cases written in plain text and the approach worked very well.

By the way, RSpec Stories is in English. And of course, all the programming languages use English for their keywords as far as I know. But I'm learning French now. And French speaking customers writing Stories in English doesn't seem to work well. And developers translating French to English introduces one more layer of indirection, which we want to avoid. I wonder if there is a solution to this problem. Maybe we can make a translator. It will be simple because it contains only RSpec stories keywords.

Experiment on Evolution

I have attended very interesting lecture at a local university.
I wish I had enough time to write down the verbs the speaker used to describe what three key figures in the lecture did.
But using my words instead, it was about - Darwin provoked the idea, Dallinger attempted to verify it experimentally, and D'Herelle established the way to experiment it.
Of course, not to mention, that uses life form whose reproduction cycle is very short so that you can observe its evolution.

D'Herelle is the start of Evolutionary medicine.
Evolutionary medicine is very interesting. Bacteriophage therapy makes sense though I acknowledge the points the speaker mentioned - it's alive so you don't necessarily know what would happen after the treatment is completed.

RSpec Rails screencast

"Story Runner top to bottom screencast"

It's very good and at the same time entertaining to follow as well.

Wind-powered generator on the top of the ski hills

Many times at the top of the ski hills and mountains, especially in the high mountains, wind blows very hard.

I have come up with the idea of putting a wind-powered generator on the top of a ski hill. It provides electricity for the lifts. And when the lifts are not used, the generated electricity can be put back to the power grid.

The Psychology of Risks

This is an article in "Communications of the ACM" magazine - January 2008 Volume 51, Number 1.

I just quote.

"The big difference seems to be this: In their personal lives, people tend to consciously and deliberately take risks - though often unaware of possibly serious consequences. When dealing with computer technology, people tend to take risks unconsciously and in some cases unwillingly."

Kent Beck on Implementation Patterns

"Kent Beck on Implementation Patterns"

I want to be in the environment where people understand what Kent says in this interview, where I can talk about it and where we can thrive for better together.

I like Spec::Rails from a different perspective as well

I like Behaviour-Driven Development very much. And that's my primary reason why I like RSpec.

I have another perspective as well about why I like Spec::Rails (RSpec for Rails). The specifications of Views are completely isolated from the Controllers and vice versa. This makes isolating and finding a problem much easier.

Also with the built-in Mock framework, Controller specifications and View specifications become more like Unit Tests (or Unit Specifications, I should say).

With stories to verify the interactions between two components acting as integration test/acceptance test, this approach is much closer to an effective software development dealing with the reality of software development such as frequent changes.

Bio-diesel hybrid car

I was listening to a radio and it was saying that electric cars were coming out.

I always thought that the next car I would buy is a hybrid car. But after hearing it, I felt like getting electric car instead when it comes out.

Also I have been wondering if they can produce hybrid car using bio-diesel. That is much cleaner than gasoline hybrid car. The source of fuel is clean because it's a plant. And the fuel itself is cleaner.

I want to work on contributing for cleaner energy source.

Installing MySQL driver gem

I have upgraded MySQL from 5.0.27, which I installed about a year ago when I bought MacBook, to 5.0.45 yesterday. The reason is that I learned from a MySQL users group meeting that there are lots of important fixes in the versions above 5.0.30.

In Ruby on Rails 2.0, it is recommended to install MySQL driver gem because the one that comes with Rails is not for production use. The gem command is described in config/database.yml.
i.e. On Mac OS X 10.5 Leopard,
sudo env ARCHFLAGS="-arch i386" gem install mysql -- --with-mysql-config=/usr/local/mysql/bin/mysql_config

Previously, installing MySQL driver gem had failed. I tried it again today now that I have the latest 5.0 version of MySQL. Then the installation was successful.

Ruby on Rails: Symbol#to_proc defined in ActiveSupport

I found it in a blog entry "An Introduction to Ruby's Enumerable Module"

It is interesting and I think I can describe it as very powerful.

Ruby on Rails 2.0: link_to for nested resources

If you specify nested resources in routes.rb such as

  map.resources :daily_contents do |daily_content|
    daily_content.resources :vocabularies   
  end

you have to specify a parameter for link_to like this:

  <% for vocabulary in @daily_content.vocabularies %>
    ..
    <%= link_to 'Show', [@daily_content, vocabulary] %>
  <% end %>

The generated URL is like this:

    http://localhost:3000/daily_contents/5/vocabularies/2

Moreover, if @daily_content.entities is just an array, which happens to contain an object of type, Vocabulary, the following works as well:

  <% for entity in @daily_content.entities %>
    ..
    <%= link_to 'Show', [@daily_content, entity] %>
  <% end %>

Again the generated URL is same as above like:

    http://localhost:3000/daily_contents/5/vocabularies/2