Scoped Struct: Feel the Tingle

posted by pete on January 29th, 2008

Unspace’s own Mike Ferrier has a gem announcement to make. Scoped Struct is a delicious morsel of meta-programming magic designed to help you organize the functionality of Ruby classes. You can now provide access to a group of related methods using association-style syntax.

Mike uses the example of a class representing an NFL player to illustrate the concept. In a vanilla class, you might see:

class Player
  def fumbles_dropped; end
  def fumbles_lost; end
  def fumbles_recovered; end
  def passes_attempted; end
  def passes_completed; end
  def passes_incomplete; end
  def pass_completion_percentage; end
end

However, with scoped_struct, you could re-organize like this:

class Player
  scope :fumbles do
    def dropped; end
    def lost; end
    def recovered; end
  end
  scope :passes do
    def attempted; end
    def completed; end
    def incomplete; end
    def completion_percentage; end
  end
end

You can then access your methods like this:

my_player.passes.attempted
my_player.passes.completed
my_player.fumbles.recovered

Pretty neat, huh? It’s just a gem install scoped_struct away.

8 Responses to “Scoped Struct: Feel the Tingle”

  1. John Philip Green Says:
    January 30th, 2008 at 02:34 PM

    Very cute. Never seen this before.

  2. Anonymous coward Says:
    February 5th, 2008 at 01:26 PM

    Great job deleting the negative comments

  3. Jerome Says:
    February 6th, 2008 at 03:41 PM

    What about ostruct objects containing ostruct objects ?

  4. Matt Says:
    February 6th, 2008 at 05:08 PM

    law of demeter anyone?

  5. Tim H. Says:
    February 6th, 2008 at 05:41 PM

    This violates several OO principles. Follow the discussion on the TorRor group:

    http://groups.google.com/group/torror/browse_thread/thread/9ad31a8a3f43ff45 http://groups.google.com/group/torror/browse_thread/thread/4fd39630ef6a1334

  6. John T Says:
    February 9th, 2008 at 09:37 PM

    Thanks for the nice piece. It’s too bad there are those who seem to get stuck on the examples and those who think CS discipline doesn’t grow or adapt to circumstances and that exceptions never arise. Too bad there are those who get caught up and miss simply appreciating someone’s effort and generosity. Thanks again.

  7. Joel Says:
    February 21st, 2008 at 04:09 AM

    Your OO violation has been reported!

    :)

    I really like it!!!

  8. Reg Braithwaite Says:
    December 24th, 2008 at 12:31 PM

    “This violates several OO principles.” => Translation to English: “This slaughters several OO sacred cows.”

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