rufus-decision¶ ↑

getting it¶ ↑

gem install rufus-decision

blog posts¶ ↑

jmettraux.wordpress.com/2009/04/25/rufus-decision-11-ruby-decision-tables/

jmettraux.wordpress.com/2010/02/17/ruote-and-decision-tables/

usage¶ ↑

More info at rufus.rubyforge.org/rufus-decision/Rufus/Decision/Table.html but here is a recap.

An example where a few rules determine which salesperson should interact with a customer with given characteristics.

require 'rubygems'
require 'rufus/decision'

TABLE = Rufus::Decision::Table.new(%{
  in:age,in:trait,out:salesperson

  18..35,,adeslky
  25..35,,bronco
  36..50,,espadas
  51..78,,thorsten
  44..120,,ojiisan

  25..35,rich,kerfelden
  ,cheerful,swanson
  ,maniac,korolev
})

# Given a customer (a Hash instance directly, for
# convenience), returns the name of the first
# corresponding salesman.
#
def determine_salesperson (customer)

  TABLE.transform(customer)["salesperson"]
end

puts determine_salesperson(
  "age" => 72) # => thorsten

puts determine_salesperson(
  "age" => 25, "trait" => "rich") # => adeslky

puts determine_salesperson(
  "age" => 23, "trait" => "cheerful") # => adeslky

puts determine_salesperson(
  "age" => 25, "trait" => "maniac") # => adeslky

puts determine_salesperson(
  "age" => 44, "trait" => "maniac") # => espadas

More at Rufus::Decision::Table

Note that you can use a CSV table served over HTTP like in :

require 'rubygems'
require 'rufus/decision'

TABLE = Rufus::DecisionTable.new(
  'http://spreadsheets.google.com/pub?key=pCkopoeZwCNsMWOVeDjR1TQ&output=csv')

# the CSV is :
#
# in:weather,in:month,out:take_umbrella?
#
# raining,,yes
# sunny,,no
# cloudy,june,yes
# cloudy,may,yes
# cloudy,,no

def take_umbrella? (weather, month=nil)
  h = TABLE.transform('weather' => weather, 'month' => month)
  h['take_umbrella?'] == 'yes'
end

puts take_umbrella?('cloudy', 'june')
  # => true

puts take_umbrella?('sunny', 'june')
  # => false

In this example, the CSV table is the direction CSV representation of the Google spreadsheet at : spreadsheets.google.com/pub?key=pCkopoeZwCNsMWOVeDjR1TQ

WARNING though : use at your own risk. CSV loaded from untrusted locations may contain harmful code. The rufus-decision gem has an abstract tree checker integrated, it will check all the CSVs that contain calls in Ruby and raise a security error when possibly harmful code is spotted. Bullet vs Armor. Be warned.

web demo¶ ↑

There is a small demo of an input table + a decision table. You can run it by doing :

gem install sinatra
git clone git://github.com/jmettraux/rufus-decision.git
cd rufus-decision
ruby demo/start.rb

and then point your browser to localhost:4567/

uninstalling it¶ ↑

gem uninstall rufus-decision

dependencies¶ ↑

The gem ‘rufus-dollar’ (rufus.rubyforge.org/rufus-dollar) and the ‘rufus-treechecker’ gem (rufus.rubyforge.org/rufus-treechecker).

mailing list¶ ↑

On the rufus-ruby list :

groups.google.com/group/rufus-ruby

irc¶ ↑

irc.freenode.net #ruote

issue tracker¶ ↑

github.com/jmettraux/rufus-decision/issues

source¶ ↑

github.com/jmettraux/rufus-decision

git clone git://github.com/jmettraux/rufus-decision.git

author¶ ↑

John Mettraux, jmettraux@gmail.com jmettraux.wordpress.com

the rest of Rufus¶ ↑

rufus.rubyforge.org

license¶ ↑

MIT

qnm/rufus-decision