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EnumeratedConstants

Emulate the handy enum seen in other programming languages

Installation

Add this line to your application's Gemfile:

gem 'enumerated_constants'

And then execute:

$ bundle

Or install it yourself as:

$ gem install enumerated_constants

Usage

Include EnumeratedConstants in a module that defines a set of related constants, e.g.

require 'enumerated_constants'

class User
  attr_accessor :role

  module Role
    extend EnumeratedConstants

    ADMIN   = 'admin'.freeze
    MANAGER = 'manager'.freeze
    GUEST   = 'guest'.freeze

    PRIVILEGED = [ADMIN, MANAGER].freeze
  end

  def validate_role!
    unless Role.include?(self.role)
      raise "Invalid role, expecting one of #{Role.all.join(', ')}"
    end
  end
end

Available methods

all

Return all constant values in the module that are not Arrays.

User::Role.all
# => ["admin", "manager", "guest"]

each

Iterate through each constant value returned by all

User::Role.each do |role|
  puts role
end
# "admin"
# "manager"
# "guest"

except

Return all constants values except for the ones passed in. Note, the arguments should be the name of the constants, not the constants' value.

User::Role.except(:guest)
# => ["admin", "manager"]

include?

Return true if the value passed in is a value of one of the constants in the module

User::Role.include?('guest')
# => true
User::Role.include?('hacker')
# => false

map

Map the values of the module to other values

User::Role.map { |role| "#{role} user" }
# => ["admin user", "manager user", "guest user"]

sample

Randomly select value(s) from the module

User::Role.sample
# => "guest"
User::Role.sample
# => "admin"
User::Role.sample(2)
# => ["manager", "admin"]

sort

Return the sorted constant values

User::Role.sort
# => ["admin", "guest", "manager"]

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. To release a new version, update the version number in version.rb, and then run bundle exec rake release to create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Contributing

  1. Fork it ( https://github.com/[my-github-username]/enumerated_constants/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