alteracoes_frequency.rb

# Module Frequency
# A small dsl written in ruby to work with frequency events (never, sometimes, always..)
#
#
# Alteracoes: 
#  * removi "if block_given?" e passei &block como parametro para #execute_with_probability
#    para remover duplicacao
#  * mudei #correct_if_string
module Frequency
  NORMALLY  = 0.75
  SOMETIMES = 0.50
  RARELY    = 0.25
  
  # always do something
  # example:
  #   always { puts "ok"}
  def always(cond={})
    yield if block_given?
  end
  
  # normally (75%) do something,
  # see sometimes method
  # example:
  #   normally { puts "ok"}
  def normally(cond={}, &block)
    execute_with_probability(cond, NORMALLY, &block)
  end
  
  # sometimes (50%) do something
  # example:
  #   sometimes do
  #      # some code
  #   end
  # or adjusting the probability
  #   sometimes :with_probability => 0.12 do
  #     # some code
  #   end
  # you can use "12%" instead 0.12
  #   sometimes(:with_probability => '13.6%') { ... }
  def sometimes(cond={}, &block)
    execute_with_probability(cond, SOMETIMES, &block)
  end
  
  alias :maybe :sometimes
  
  # rarely (25%) do something,
  # see sometimes method
  # example:
  #   rarely { puts "ok"}
  def rarely(cond={}, &block)
    execute_with_probability(cond, RARELY, &block)
  end
  
  # never do something
  # example:
  #   never { puts "ok"}  
  def never(cond={})
  end
  
  private
  def execute_with_probability(conditions,default)
    rate = conditions[:with_probability] || default
    rate = Float(rate) rescue correct_if_string(rate)
    raise "probability must be [0..100]%" unless 0 <= rate && rate <= 1 
    yield if Kernel.rand < rate
  end
  
  def correct_if_string(rate)
    rate.to_f / 100
  end
end