Womb

Womb wraps around an object to present a chainable interface for defining objects. It also provides short aliases for longer method names and helpers to reduce boiler plate.

Usage

Once wrapped around an object, Womb stores all messages via method_missing and then sends them to the object when the birth method is called, returning the defined object.

require 'womb'

pi = 3.14

Circle = Womb[Class.new]
  .attr_reader(:radius)
  .define_method(:initialize) { |radius| @radius = radius }
  .define_method(:circumference) { 2 * pi * radius }
  .define_method(:area) { pi * radius ** 2 }
  .birth

Circle.new(3).area # 28.26

For shorthand, def and assign can be used as aliases for define_method and define_singleton_method respectively, and init can be used to create an initialize method that simply sets instance variables from it's arguments.

require 'git'

Repo = Womb[Class.new]
  .assign(:open) { |path| new(Git.open(path)) }
  .assign(:clone) { |url, path| new(Git.clone(url, path)) }
  .init(:git)
  .def(:checkout) { |branch| git.checkout(branch); self }
  .def(:branch) { |branch| git.branch(branch).checkout; self }
  .def(:add) { git.add(all: true); self }
  .def(:commit) { |message| git.commit(message); self }
  .def(:push) { git.push('origin', git.current_branch, force: true); self }
  .def(:ls) { add; git.ls_files.keys }
  .private
  .attr_reader(:git)
  .birth

Repo.open('../my_local_repo').add.commit('Updating with changes').push

An additional helper, send_to_singleton, can be used to send messages to the object's singleton class.

Matrix = Womb[Class.new]
  .init(:v1, :v2)
  .attr_reader(:v1, :v2)
  .send_to_singleton(:alias_method, :[], :new)
  .def(:determinant) { v1[0] * v2[1] - v2[0] * v1[1] }
  .birth

Matrix[[2, 2], [1, 3]].determinant # 4

If you prefer not to define a method with a block directly, it can defined as a lambda and passed in using the to_proc operator, &. The objects private state can still be accessed with instance variables.

move = ->(dist, angle) do
  angle = angle * Math::PI / 180
  @x += dist * Math.cos(angle)
  @y += dist * Math.sin(angle)
  puts self
  self
end

Turtle = Womb[Class.new]
  .init(:x, :y)
  .def(:move, &move)
  .def(:to_s) { "Turtle (#{@x.round}, #{@y.round})" }
  .birth

Turtle.new(0, 0).move(1, 0).move(2, 90)
# Turtle (1, 0)
# Turtle (1, 2)

Installation

Add your Gemfile:

gem 'womb'

Contributing

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request