Playing with structs and Enumerable.find

struct_and_find.rb

class SampleContracts
  BASE_PATH = "downloads/sample_contracts/"

  Contract = Struct.new(:type, :name, :title) do
    # Struct responds to .call so it can be used for Enumerable.find(ifnone)
    def self.call
      new
    end

    # By adding this method we get a struct that plays nicely with destructuring
    alias_method :to_ary, :to_a

    def filename
      "#{title}.pdf"
    end

    def path
      File.join(BASE_PATH, filename)
    end
  end

  ALL = [
    Contract.new(:boat, "Boat", "Boat Rental Agreement"),
    Contract.new(:rv, "RV", "RV Rental Agreement"),
    Contract.new(:home, "Home", "Home Rental Agreement"),
    Contract.new(:atv, "ATV", "ATV Rental Agreement"),
    Contract.new(:snowmobile, "Snowmobile", "Snowmobile Rental Agreement"),
    Contract.new(:personal_watercraft, "Personal Watercraft", "Watercraft Rental Agreement")
  ]

  def self.all
    ALL
  end

  def self.new_contract
    Contract.new
  end

  def self.each(&block)
    all.each(&block)
  end

  def self.types
    all.map(&:type)
  end

  def self.names
    all.map(&:name)
  end

  def self.titles
    all.map(&:title)
  end

  def self.find(type)
    all.find(Contract){ |contract| contract.type == type }
  end

  def self.alt_find(type)
    # Anything that responds to .call - like a method object
    all.find(method(:new_contract)){ |contract| contract.type == type }
  end

  def self.path_for(type)
    find(type).path
  end
end


puts SampleContracts.all
#<struct SampleContracts::Contract type=:boat, title="Boat Rental Agreement">
#<struct SampleContracts::Contract type=:rv, title="RV Rental Agreement">
#<struct SampleContracts::Contract type=:home, title="Home Rental Agreement">
#<struct SampleContracts::Contract type=:atv, title="ATV Rental Agreement">
#<struct SampleContracts::Contract type=:snowmobile, title="Snowmobile Rental Agreement">
#<struct SampleContracts::Contract type=:personal_watercraft, title="Watercraft Rental Agreement">

puts SampleContracts.titles
# Boat Rental Agreement
# RV Rental Agreement
# Home Rental Agreement
# ATV Rental Agreement
# Snowmobile Rental Agreement
# Watercraft Rental Agreement

SampleContracts.each do |contract|
  puts contract.type
end
# boat
# rv
# home
# atv
# snowmobile
# personal_watercraft

SampleContracts.each do |(type, name, title)|
  puts "#{type}, #{name}, #{title}"
end
# boat, Boat, Boat Rental Agreement
# rv, RV, RV Rental Agreement
# home, Home, Home Rental Agreement
# atv, ATV, ATV Rental Agreement
# snowmobile, Snowmobile, Snowmobile Rental Agreement
# personal_watercraft, Personal Watercraft, Watercraft Rental Agreement

puts SampleContracts.find(:boat)
#<struct SampleContracts::Contract type=:boat, title="Boat Rental Agreement">

puts SampleContracts.alt_find(:boat)
#<struct SampleContracts::Contract type=:boat, title="Boat Rental Agreement">

puts SampleContracts.find(:missing)
#<struct SampleContracts::Contract type=nil, title=nil>

puts SampleContracts.alt_find(:missing)
#<struct SampleContracts::Contract type=nil, title=nil>

puts SampleContracts.path_for(:home)
# downloads/sample_contracts/Home Rental Agreement.pdf