TinyStruct

Often we want simple Ruby classes that follow the pattern of accepting data as arguments to the initializer and storing them as attr_readers. For example:

class User
  attr_reader :name, :email

  def initialize(name, email)
    @name = name
    @email = email
  end

  def to_s
    "#{name} <#{email}>"
  end
end

user = User.new('Harry Potter', 'hpotter@hogwarts.edu')
# => #<User @name="Harry Potter" @email="hpotter@hogwarts.edu">

This is pretty common, and more or less resembles a struct and an associated initializer in many other languages (see initializer lists in C++ or case classes in Scala).

You could refactor the above to inherit from Ruby's own Struct class, as in:

class User < Struct.new(:name, :email)
  def to_s
    "#{name} <#{email}>"
  end
end

This totally works! Struct::new returns a class, from which User then inherits. This pattern is great because it encapsulates the initialization and enforces a certain consistency over the way objects are created within a codebase.

However, there is a certain amount of bloat that comes from using the Struct class. Ruby defines a number of enumerable and comparison methods to allow them to function more like structs in other languages. This is why we built TinyStruct, which is effectively the same thing as a Struct but it does much less:

• In Struct classes all parameters are optional, in TinyStruct they are all required (encouraging explicit values for each member).
• In Struct classes each parameter is accessible through an attr_accessor, in TinyStruct they are accessible through attr_readers (encouraging more data encapsulation).
• In Struct classes you can call all kinds of querying methods on the objects as if they were an enumerable of the various values they represent (e.g., to_a, to_h, size, [], values_at, etc.), in TinyStruct none of these methods are defined (minifying the surface area of the class to encourage explicit method definitions if necessary).

You can use TinyStruct in the exact same way that you could use Struct (by inheriting from an object returned by the ::new method.

Use Struct if you need the flexibility and extra query methods provided by the constructor. If not, consider using TinyStruct.

Add this line to your application's Gemfile:

gem 'tiny_struct'

And then execute:

$ bundle

Or install it yourself as:

$ gem install tiny_struct

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/CultureHQ/tiny_struct.

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