Stronger

Stronger is a basic run-time type-safety kit for Ruby, which introduces a couple of tools for simple run-time type checking.

There's nothing revolutionary here. Just a few convenient types and methods to ease the burden of the type-conscious rubyist.

gem install stronger and require 'stronger' in your code.

Stronger provides some type-checking wrappers around Ruby's Hash and Array classes, which help give you a bit of type-safety in the values you can expect from these collections.

Typed arrays check anything appended.

  arr = Stronger::TypedArray.new(Integer)
  arr.push 5

  arr.push 4 # raises TypeError

They also refuse to concatenate with other TypedArrays not of the same type.

Typed hashes check values added to ensure type.

  hash = Stronger::TypedHash.new(String)
  hash[:first] = 'Groovy'
  hash[2] = :woah_there # raises TypeError

Some class methods are provided in the PropertyDefinition module which allows you to define properties on classes. Properties are required by default, can be set via the constructor, the private set_properties method, or setters.

  class Person
    property :name, type: String
    property :phone_number, type: String, required: false
  end

  addr = AddressBookEntry.new(name: "Boris")
  addr.name #=> 'Boris'
  addr.name = 3 # Raises Stronger::InvalidProperty

Stronger has a very simple (and very dumb) concept of an Interface, which is just a list of methods objects must respond to encapsulated in an object. These Interface objects can be treated as types however, which makes duck-typing with Collections and Properties a lot nicer.

  AnimalInterface = Stronger::Interface.new(:move, :make_noise)

  class Dog
    def move
    end

    def make_noise
    end
  end

The AnimalInterface defined above can be used in place of classes for types in Stronger's properties and typed collections.

The Stronger::TypeChecking refinement provides a is_strong? method on Object which allows you to check types yourself. It behaves like is_a? but includes support for interface checking.

  use Stronger::TypeChecking

  BoatInterface = Stronger::Interface.new(:float)

  Object.new.is_strong?(Object) # => true
  Object.new.is_strong?(Boat) # => false

Fork and open a PR. Please include tests and ensure rake test runs.

See LICENSE