# ExEnum
[](https://travis-ci.org/efcasado/exenum)[](https://coveralls.io/github/efcasado/exenum?branch=master)[](https://hex.pm/packages/exenum)
**ExEnum** is a simple [enumeration](https://en.wikipedia.org/wiki/Enumeration)
library for Elixir.
## Usage
Just add the following line to your Elixir module and you are ready to go.
```elixir
use ExEnum, from: [ ... ]
```
By adding the above line to your module, it will automatically acquire the
following functionality:
- Ability to list all the values in the enumeration
- Ability to check if an arbitrary value belongs to the enumeration
- Ability to access a value from the enumeration via a dedicated accessor
function
- Ability to list all the keys that can be used to access each of the
enumeration values
This functionality is realised by means of the following functions: **values/0**,
**is_valid?/1**, **from_value/1**, **keys/0** and **\<key>/0**. Note that your module will have as many
**\<key>/0** functions as enumeration values in the `use ExEnum, from: [ ... ]`
clause.
## Example(s)
```elixir
defmodule Planet do
use ExEnum, from: [
"MERCURY",
"VENUS",
"EARTH",
"MARS",
"JUPITER",
"SATURN",
"URANUS",
"NEPTUNE"
]
end
Planet._MERCURY
# => "MERCURY"
Planet.values
# => ["MERCURY", "VENUS", "EARTH", "MARS", "JUPITER",
# "SATURN", "URANUS", "NEPTUNE"]
Planet.keys
# => [:_MERCURY, :_VENUS, :_EARTH, :_MARS, :_JUPITER,
# :SATURN, :_URANUS, :_NEPTUNE]
Planet.is_valid?("PLUTO")
# => false
Planet.from_value("EARTH")
# => "EARTH"
Planet.is_valid?("PLUTO")
# => nil
```
```elixir
defmodule Direction do
use ExEnum, from: [
{:north, 1},
{:east, 2},
{:south, 3},
{:west, 4}
]
end
Direction.north
# => 1
Direction.values
# => [1, 2, 3, 4]
Direction.keys
# => [:north, :east, :south, :west]
Direction.is_valid?(:north_east)
# => false
Direction.from_value(:north_east)
# => nil
Direction.from_value(:north)
# => 1
```
## Installation
If [available in Hex](https://hex.pm/docs/publish), the package can be installed as:
1. Add ExEnum to your list of dependencies in `mix.exs`:
def deps do
[{:exenum, "~> 0.0.1"}]
end
2. Ensure ExEnum is started before your application:
def application do
[applications: [:exenum]]
end
## Author(s)
- Enrique Fernandez `<efcasado(at)gmail.com>`
## License
> The MIT License (MIT)
>
> Copyright (c) 2016, Enrique Fernandez
>
> Permission is hereby granted, free of charge, to any person obtaining a copy
> of this software and associated documentation files (the "Software"), to deal
> in the Software without restriction, including without limitation the rights
> to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
> copies of the Software, and to permit persons to whom the Software is
> furnished to do so, subject to the following conditions:
>
> The above copyright notice and this permission notice shall be included in
> all copies or substantial portions of the Software.
>
> THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
> AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
> OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
> THE SOFTWARE.
