it's Valuable -- like attr_accessor on steriods

Take a look at the valuable library.

I recently worked on a Rails project where most of the domain-related data came from a HyperCube database, rather than a relational one. I have to admint, albeit begrudgingly, that it provided a lot of value. At the same time, incorporating non-relational data with Rails was at best incrediby painful.

One "feature" of the hypercube was that we didn't ever get a complete schema. Data was provided when it was available, and when it wasn't available, it just didn't exist. We needed a dry way to model the parts of the data we were using. We also wanted to be able to transparently ignore any other data that might unexpectedly appear. Finally, for my own sanity, I wanted it to feel as much like a rails model as possible.

Goals:

• dry class decorators
• generate getters and setters for each attribute
• generate a class-level list of the attributes we handled
• provide an instance-level attribute hash like Rails 
• optionally provide type casting ( '3' + '3' is not the same as 3+3)
  
• allow default values

From the Readme, Here's an example of its usage. I'm having an odd issue with blogger, so excuse the inheritance symbol:

class BaseballPlayer : Valuable::Base

  has_value :at_bats, :klass => Integer

  has_value :hits, :klass => Integer

  has_value :jersey, :klass => Jersey, :default => 'unknown'

  has_value :league, :default => 'unknown'

  has_value :name

  has_collection :teammates

  def roi

    hits/at_bats.to_f if hits && at_bats

  end

end

class Jersey : String

  def initialize(object)

    super "Jersey Number #{object}"

  end

end

>> joe = BaseballPlayer.new(:name => 'Joe', :hits => 5, :at_bats => 20)

>> joe.at_bats

=> 20

>> joe.league

=> 'unknown'

>> joe.roi

=> 0.25

>> joe.at_bats = nil

>> joe.roi

=> nil

>> joe.teammates

=> []

>> joe.jersey

=> 'unknown'

>> joe.jersey = 20

>> 'Jersey Number 20'

This has also come in handy with the Flix4r code I've been writing... more about that soon.