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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.

Installation

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

Usage

  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. <code>()[]*</code>) 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

Development

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.

Contributing

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

License

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