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TypedStruct

A Typed Struct is a lightweight data structure inspired by Dry Struct, which allows for reading and writing properties while making use of a flexible and powerful type checking system, which also incorporates Ruby's RBS for type definitions.

Example

require 'typed_struct' # unless using rails

User = TypedStruct.new name: String, # an instance of String
                       age: Integer, # an instance of Integer
                       username: /\w{4,}/, # must match given Regexp
                       rating: (0..5), # must be value from 0 to 5
                       type: "User", # must by a string with value "User"
                       interests: Rbs("Array[String]"), # an RBS generic type (an Array of Strings)
                       preferences: Rbs("{ opt_out_of_emails: bool, additional: untyped }") # RBS record type

clive = User.new name: "Clive",
                 age: 22,
                 interests: %w[surfing skiing],
                 preferences: { opt_out_of_emails: true, additional: { preferred_theme: :dark } },
                 type: "User",
                 rating: 4,
                 username: "cliveabc"

clive.age # 22
clive.age = '22' # => Error
clive.preferences = { "opt_out_of_emails" => true, "additional" => nil } # error - type mismatch, not Symbol keys
clive.freeze # no more changes can be made

Note that a TypedStruct inherits from Struct directly, so anything from Struct is also available in TypedStruct - see Struct docs for more info.

See RBS reference for more info on writing RBS types

Installation

Add this line to your application's Gemfile:

gem 'typed_struct'

And then execute:

$ bundle install

Or install it yourself as:

$ gem install typed_struct

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec 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 the created tag, and push the .gem file to rubygems.org.

Contributing

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

License

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