Lean::Attributes

Lean::Attributes is inspired by gems like Virtus or FastAttributes. It allows one to define typed attributes on arbitrary Ruby classes. Lean::Attributes aims to be roughly as fast as FastAttributes but has a few syntactical differences in addition to support for default values.

Status

Installation

Add this line to your Gemfile:

gem 'lean-attributes', '~> 0.2'

And then execute:

$ bundle

Or install it yourself with:

$ gem install lean-attributes

Usage

require 'lean-attributes'

class Book
  include Lean::Attributes

  attribute :title,     String
  attribute :name,      String
  attribute :pages,     Integer
  attribute :authors,   Array
  attribute :published, Date
  attribute :sold,      Time,     default: :time_now
  attribute :finished,  DateTime
  attribute :format,    Symbol,   default: :hardcover

  private

  def time_now
    Time.now.utc
  end
end

book = Book.new(
  title:      'There and Back Again',
  name:       'The Hobbit',
  pages:      '200',
  authors:    'Tolkien',
  published:  '1937-09-21',
)
book.finished = '1937-08-20 12:35'

book.format # => :hardcover
book.sold # => 2015-09-15 23:06:34 UTC
book # =>
# #<Book:0x007fcb7613b610
#   @authors=["Tolkien"],
#   @finished=
#     #<DateTime: 1937-08-20T12:35:00+00:00 ((2428766j,45300s,0n),+0s,2299161j)>,
#   @format=:hardcover,
#   @name="The Hobbit",
#   @pages=200,
#   @published=#<Date: 1937-09-21 ((2428798j,0s,0n),+0s,2299161j)>,
#   @sold=2015-09-15 23:06:34 UTC,
#   @title="There and Back Again">

Coercion

The coercion capabilities included in this gem are poor by design and will only handle trivial use cases. Whenever you set an attribute, generated coercion methods are called. You can override these methods to create your own coercion rules.

class ReadingProgress
  include Lean::Attributes

  attribute :current_page, Integer, default: 1

  private

  def coerce_current_page(value)
    value = begin
      value.to_i
    rescue NoMethodError
      1
    end

    value = 1 if value < 1
    value
  end
end

Another way to contain such behavior is to create a CurrentPage class to represent your attribute instead of an Integer. The power is yours.

Benchmarks

Lean::Attributes is meant to be relatively lightweight and fast.

FastAttributes: without values                          :  3499535.3 i/s
Lean::Attributes: without values                        :  3467944.9 i/s - 1.01x slower
Lean::Attributes: integer values for integer attributes :   151398.8 i/s - 23.11x slower
FastAttributes: integer values for integer attributes   :   140099.8 i/s - 24.98x slower
Lean::Attributes: string values for integer attributes  :   139070.9 i/s - 25.16x slower
FastAttributes: string values for integer attributes    :   124387.2 i/s - 28.13x slower
Virtus: integer values for integer attributes           :    36776.0 i/s - 95.16x slower
Attrio: integer values for integer attributes           :    19452.5 i/s - 179.90x slower
Virtus: without values                                  :    18184.8 i/s - 192.44x slower
Attrio: string values for integer attributes            :    17689.9 i/s - 197.83x slower
Attrio: without values                                  :    12769.1 i/s - 274.06x slower
Virtus: string values for integer attributes            :     5043.4 i/s - 693.88x slower

Versioning

Lean:Attributes uses Semantic Versioning 2.0.0

Contributing

Fork it ( https://github.com/lleolin/lean-attributes/fork )
Create your feature branch (git checkout -b my-new-feature)
Commit your changes (git commit -am 'Add some feature')
Push to the branch (git push origin my-new-feature)
Create new Pull Request