PrivateAttrs

Adds a few to Ruby's Clss object to allow for private attr readers/writers/accessors.

Installation

Add this line to your application's Gemfile:

gem 'private_attrs'

And then execute:

$ bundle

Or install it yourself as:

$ gem install private_attrs

Usage

Inside any class object you can now define private attr methods.

class Crocodile

  private_attr_reader :temper

  def intialize(temper)
    @temper = temper
  end
end

Crocodile.new('angry').temper # => NoMethodError "private method 'temper' called for ...

Why

In short, because existing patterns to do this are ugly. This particular pattern violates 'the scissor rule' of coding in that there is not a clear separation between public and private methods.

class Crocodile

  private

  attr_reader :temper

  public

  attr_reader :asleep

  def initialize(temper)
    @temper = temper
  end

  def bites?
    if angry? && !asleep?
  end

  private

  def angry?
    temper == 'angry'
  end

  def asleep?
    current_time = Time.now
    (current_time.hour >= 17) and (current_time.hour <= 21)
  end
end

This use case is better but still not ideal as we want all of our attrs methods definded at the top of any given class.

class Truck

  attr_reader :transmission_type
  attr_reader :weight

  def initialize(wheel_count:, transmission_type:, weight:)
    @wheel_count = wheel_count
    @transmission_type = transmission_type
    @weight =  weight
  end

  def oversized
    wheel_count > 4
  end

  def driver_must_shift?
    transmission_type == :manual
  end

  private

  attr_reader :wheel_count
end

Other patterns are even worse...

class Pet

  attr_accessor :species
  private :species
  private :species=

  attr_reader :hairy
  private :hairy

  def initialize(species, hairy)
    #...
  end
end

License

The gem is available as open source under the terms of the MIT License.