gistfile1.rb

require 'rubygems'
require 'benchmark'
require 'rulebook'

class Foo

  [:admin, :blah].each do |role|
    define_method "is_#{role}?" do
      true
    end 
  end 

end 

class Bar
  
  rule /is_(admin|blah)\?/ do |role|
    true
  end 

end 

class Baz
  
  def is_admin?
    true
  end 
  
  def is_blah?
    true
  end 
  
end 


class Quux
  
  [:admin, :blah].each do |role|
    eval <<-EOC
      def is_#{role}?
        true
      end 
    EOC
  end 

end 
    
foo = Foo.new
bar = Bar.new
baz = Baz.new
quux = Quux.new

puts "method defined with define_method:   #{Benchmark.realtime{100_000.times{foo.is_admin?}}}"
puts "method defined with rulebook:        #{Benchmark.realtime{100_000.times{bar.is_admin?}}}"
puts "method defined by hand (with def):   #{Benchmark.realtime{100_000.times{baz.is_admin?}}}"
puts "method defined with eval (with def): #{Benchmark.realtime{100_000.times{quux.is_admin?}}}"

# method defined with define_method:   0.0745489597320557
# method defined with rulebook:        1.54464817047119
# method defined by hand (with def):   0.0245590209960938
# method defined with eval (with def): 0.02919602394104

Hmm. I havn't had a chance to run benchmarks yet.

Maybe caching the rules would make a difference.. I'll work on this.
If you have any idea's, feel free to help out. It would be greatly appreciated.