This gem provide attr_required and attr_optional like attr_accessor.

REQUIRED and OPTIONAL are common terminology in RFCs, and used for protocol parameters. This gem helps RFC library developers to define which parameters (attributes in Ruby world) are REQUIRED and which are OPTIONAL. It might be also helpful for other developers.

I've developed this gem to use for rack-oauth2, a Rack-based OAuth 2.0 library.


gem install attr_required


# Attributes Definitions

require 'attr_required'
require 'attr_optional'

class A
  include AttrRequired, AttrOptional
  attr_required :required_a
  attr_optional :optional_a

class B < A
  attr_required :required_b
  attr_optional :optional_b

# Class Methods

A.required_attributes #=> [:required_a]
B.required_attributes #=> [:required_a, :required_b]
A.optional_attributes #=> [:optional_a]
B.optional_attributes #=> [:optional_a, :optional_b]

A.attr_required?(:required_a) #=> true
B.attr_optional?(:optional_b) #=> true

# Instance Methods

@a =
@b =

@a.required_attributes #=> [:required_a]
@b.required_attributes #=> [:required_a, :required_b]
@a.optional_attributes #=> [:optional_a]
@b.optional_attributes #=> [:optional_a, :optional_b]

@a.attr_required?(:required_a) #=> true
@a.attr_optional?(:optiona_a)  #=> true

@a.attr_missing? #=> true
@a.attr_missing  #=> [:required_a]
@a.attr_missing! #=> raise AttrRequired::AttrMissing
@a.required_a = "foo"
@a.attr_missing? #=> false
@a.attr_missing  #=> []
@a.attr_missing! #=> do nothing

Check spec/attr_(required|optional).rb for more details.

Note on Patches/Pull Requests

  • Fork the project.

  • Make your feature addition or bug fix.

  • Add tests for it. This is important so I don't break it in a future version unintentionally.

  • Commit, do not mess with rakefile, version, or history. (if you want to have your own version, that is fine but bump version in a commit by itself I can ignore when I pull)

  • Send me a pull request. Bonus points for topic branches.


Copyright © 2010 nov matake. See LICENSE for details.