OpenStruct

An OpenStruct is a data structure, similar to a Hash, that allows the definition of arbitrary attributes with their accompanying values. This is accomplished by using Ruby's metaprogramming to define methods on the class itself.

The ostruct library comes pre-packaged with Ruby. No installation is necessary.

  require "ostruct"

  person = OpenStruct.new
  person.name = "John Smith"
  person.age  = 70

  person.name      # => "John Smith"
  person.age       # => 70
  person.address   # => nil

An OpenStruct employs a Hash internally to store the attributes and values and can even be initialized with one:

  australia = OpenStruct.new(:country => "Australia", :capital => "Canberra")
    # => #<OpenStruct country="Australia", capital="Canberra">

Hash keys with spaces or characters that could normally not be used for method calls (e.g. ()[]*) will not be immediately available on the OpenStruct object as a method for retrieval or assignment, but can still be reached through the Object#send method.

  measurements = OpenStruct.new("length (in inches)" => 24)
  measurements.send("length (in inches)")   # => 24

  message = OpenStruct.new(:queued? => true)
  message.queued?                           # => true
  message.send("queued?=", false)
  message.queued?                           # => false

Removing the presence of an attribute requires the execution of the delete_field method as setting the property value to +nil+ will not remove the attribute.

  first_pet  = OpenStruct.new(:name => "Rowdy", :owner => "John Smith")
  second_pet = OpenStruct.new(:name => "Rowdy")

  first_pet.owner = nil
  first_pet                 # => #<OpenStruct name="Rowdy", owner=nil>
  first_pet == second_pet   # => false

  first_pet.delete_field(:owner)
  first_pet                 # => #<OpenStruct name="Rowdy">
  first_pet == second_pet   # => true

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 rubygems.org.

Bug reports and pull requests are welcome on GitHub at https://github.com/ruby/ostruct.

The gem is available as open source under the terms of the 2-Clause BSD License.