AttrSetting

Why use AttrSetting?

Imagine having a class definition similar to this one:

class Configuration
  attr_accessor :send_email

  def initialize
    @send_email = true
  end

  def send_email?
    send_email
  end
end

The class defines a Configuration object that contains a setting for whether the application should send an email. The send_email setting defaults to true.

There is a lot of repitition of "send_email" in this class definition. Any changes to this setting, be it a rename or deletion, requires changing multiple lines of code spread out over the class definition.

AttrSetting DRYs up this definition in a clear, concise way:

class Configuration
  extend AttrSetting

  attr_setting :send_email, true
end

No more repitition. Only one line of code to change.

Installation

Add this line to your application's Gemfile:

gem 'attr_setting'

And then execute:

$ bundle

Or install it yourself as:

$ gem install attr_setting

Usage

attr_setting provides enhanced functionality to Ruby's attr_accessor.

To use, require the library and extend the module:

require 'attr_setting'

class Config
  extend AttrSetting
end

A monkeypatch is available to auto-extend AttrSetting for use in all Module and Class definitions:

require 'attr_setting/core_ext/module'

attr_setting adds default values to attr_accessor in the form of a second argument or block:

require 'attr_setting'

class Config
  extend AttrSetting

  attr_setting :foo, 'Second argument'
  attr_setting(:bar) { 'Block' }
end

config = Config.new
config.foo          # => 'Second argument'
config.bar          # => 'Block'

The block is evaluated in the context of the object:

require 'attr_setting'

class Config
  extend AttrSetting

  attr_setting :foo, 'Foo value'
  attr_setting(:bar) { foo }
end

config = Config.new
config.foo          # => 'Foo value'
config.bar          # => 'Foo value'

The block is lazily evaluated:

require 'attr_setting'

class Config
  extend AttrSetting

  attr_setting :foo
  attr_setting(:bar) { foo }
end

config = Config.new
config.foo = 'New value'
config.bar               # => 'New value'

attr_setting also adds a couple other features besides default values for attr_accessor.

It adds a predicate method:

require 'attr_setting'

class Config
  extend AttrSetting

  attr_setting :foo
end

config = Config.new
config.foo?             # => false
config.foo = :something
config.foo?             # => true

It adds a bang method to reset values to their defaults:

require 'attr_setting'

class Config
  extend AttrSetting

  attr_setting :foo, 'Default'
end

config = Config.new
config.foo               # => 'Default'
config.foo = 'New value'
config.foo               # => 'New value'
config.foo!
config.foo               # => 'Default'

It treats getters with an argument as setters:

require 'attr_setting'

class Config
  extend AttrSetting

  attr_setting :foo
end

config = Config.new
config.foo('New value')
config.foo              # => 'New value'

Development

After checking out the repo, run bin/setup to install dependencies. Then, 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.

Contributing

1. Fork it ( https://github.com/[my-github-username]/attr_setting/fork )
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