Collection

Type-checked set and array

The Collection library provides implementations of type-checked set and array classes.

Collections are constructed with a type parameter that controls the type of element that can be added to the collection.

type = String

array = Collection::Array.new(type)

array.add('something')

array.any? { |item| item == 'something' }
# => true

array.add(:not_a_string)
# => :not_a_string must be a String (ArgumentError)

type = String

cls = Collection::Array[type]

array = cls.new

items = ['something', 'something else']

array = Collection::Array(items)

items = ['something', 'something else']

cls = Collection::Set[String]

cls.build(items)

An instance implementation can be specified by passing it in a block to either its generic constructor or its coercion method.

cls = Collection::Array[String] do
  def underscore
    items.join('_')
  end
end

array = cls.new

array.add('something')
array.add('else')

array.underscore
# => something_else

items = ['something', 'else']

array = Collection::Array(items) do
  def underscore
    items.join('_')
  end
end

array.underscore
# => something_else

A collection defined by either the generic-style class definition or the coercion method creates a unique class in the Collection namespace.

Collection::Array[String]
# => Collection::Array::String

Collection::Array(['something', 'else']).class
# => Collection::Array::String

Once a dynamic collection class is defined, an attempt will not be made again to re-define it upon subsequent declarations.

The Collection::Set implements the same interface as the Collection::Array. The examples above apply equally to Collection::Set.

Collection::Set and Collection::Array implement Ruby's Enumerable module. The standard set of methods available on any Ruby enumerable are available to both Collection::Set and Collection::Array.

The collection library is released under the MIT License.