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A Ruby class extension for binding initialize method args to instance vars.
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bin bundle gem teyu Aug 5, 2019
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A Ruby class extension for binding initialize method args to instance vars.
Inspired by attr_extras gem.

Teyu(手湯) is hand bath at Yugawara station.
I scratched this gem in Yugawara hot spring hotel.

Yugawara-machi | Yugawara station square maintenance construction was completed!


teyu_init defines initialize method and binds args to same name instance variables.

require 'teyu'

class Foo
  extend Teyu
  teyu_init :a, :b

  # Equal to...
  # def initialize(a, b)
  #   @a = a
  #   @b = b
  # end

class Bar
  extend Teyu
  teyu_init :c, :d!

  # def initialize(c, d:)
  #   @c = c
  #   @d = d
  # end

class Baz
  extend Teyu
  teyu_init :e, f: 'fff'

  # def initialize(e, f: 'fff')
  #   @e = e
  #   @f = f
  # end


Add this line to your application's Gemfile:

gem 'teyu'

And then execute:

$ bundle

Or install it yourself as:

$ gem install teyu


After checking out the repo, run bin/setup to install dependencies. Then, run rake test to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to


Bug reports and pull requests are welcome on GitHub at This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.


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

Code of Conduct

Everyone interacting in the Teyu project’s codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.

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