DefInitialize

Another approach to reduce initialization boilerplate

Installation

Add this line to your application's Gemfile:

gem 'def_initialize'

And then execute:

$ bundle

Or install it yourself as:

$ gem install def_initialize

Usage

class Employee
  include DefInitialize.with("name, uuid = SecureRandom.uuid, *params, age:, position: 'manager', **opts")
end

# is the same as:

class Employee
  def initialize(name, uuid = SecureRandom.uuid, *params, age:, position: 'manager', **opts)
    @name = name
    @uuid = uuid
    @params = params
    @age = age
    @position = position
    @opts = opts
  end

  private

  attr_reader :name, :uuid, :params, :age, :position, :opts
end

By convention, parameters starting with underscore symbol '_' are ignored:

class Point
  include DefInitialize.with("x, y, _c")
end

# transforms to:

class Point
  def initialize(x, y, _c) # Note that `_c` is still required to pass
    @x = x
    @y = y
  end

  private

  attr_reader :x, :y
end

DSL

Alternatively, you can extend a class with DefInitialize::DSL and use def_initialize method. Note, how close it looks to the native declaration!

class Base
  extend DefInitialize::DSL
end

class Circle < Base
  def_initialize("radius")
end

class Rectangle < Base
  def_initialize("length, width")
end

Access control

You can specify level of access for your readers and writers:

class Person < Base
  def_initialize("name", readers: :public, writers: :private)
end

# transforms to:

class Person
  def initialize(name)
    @name = name
  end

  attr_reader :name

  private

  attr_writer :name
end

Allowed values are :public, :private, :protected and nil. If value is nil, accessors won't be defined at all.

default value for readers is private, default value for writers is nil

What should I do in more complex cases?

Just write plain old def initialize.

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 tags, and push the .gem file to rubygems.org.

Contributing

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

License

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