payments_importer.rb

module ChurnLogger
  # include Loggable
  alias info puts
  alias error puts

  def perform_with_log(*args)
    info 'starting new payments importing'
    perform_without_log(*args)
  rescue => exception
    error exception.to_s
  ensure
    info 'finished import new payments'
  end

  def churns_with_log
    churns_without_log.tap do |churns|
      if churns.empty?
        info 'no churn to verify payment'
      else
        info "#{churns.count} churns to verify payment"
      end
    end
  end

  def churns_to_save_with_log
    churns_to_save_without_log.tap do |churns_to_save|
      if churns_to_save.empty?
        info "no new paid churns were identified"
      else
        info "#{churns_to_save.count} paid churns were identified"
      end
    end
  end

  def self.append_features(mod)
    super
    mod.class_eval do
      ChurnLogger.instance_methods.grep(/(.*)_with_log$/) do
        alias_method "#{$1}_without_log", $1
        alias_method $1, "#{$1}_with_log"
      end
    end
  end

end

class PaymentsImporterStub

  def perform(params={})
    churns
    churns_to_save
    # raise "AAAAA"
  end

  def churns
    []
  end

  def churns_to_save
    %w(1 2 3)
  end

  include ChurnLogger
end


class PaymentsImporter

  def churns; Churn.not_paid; end

  def entries 
    Acme::Database.execute(Query.for :new_payments, :churns => churns)
  end

  def paid_churns
    entries.map { |entry| entry[:payment_id] }
  end

  def churns_to_save
    churns.select do |churn|
      paid_churns.any? { |payment_id| payment_id == churn.payment_id }
    end
  end

  def perform(params={})
    churns_to_save.each(&:mark_as_paid!) unless churns.empty?
  end

  include ChurnLogger
end


puts "--- PaymentsImporterStub ---"
PaymentsImporterStub.new.perform() # => ["1", "2", "3"]
puts "--- PaymentsImporter ---"
PaymentsImporter.new.perform() # => nil
# >> --- PaymentsImporterStub ---
# >> starting new payments importing
# >> no churn to verify payment
# >> 3 paid churns were identified
# >> finished import new payments
# >> --- PaymentsImporter ---
# >> starting new payments importing
# >> uninitialized constant PaymentsImporter::Churn
# >> finished import new payments