Configatron

Configatron makes configuring your applications and scripts incredibly easy. No longer is a there a need to use constants or global variables. Now you can use a simple and painless system to configure your life. And, because it's all Ruby, you can do any crazy thing you would like to!

One of the more important changes to V3 is that it now resembles more a Hash style interface. You can use [], fetch, each, etc... Actually the hash notation is a bit more robust since the dot notation won't work for a few property names (a few public methods from Configatron::Store itself).

Installation

Add this line to your application's Gemfile:

gem 'configatron'

And then execute:

$ bundle

Or install it yourself as:

$ gem install configatron --pre

Usage

Once installed you just need to require it:

require 'configatron'

Simple

configatron.email = 'me@example.com'
configatron.database.url = "postgres://localhost/foo"

Now, anywhere in your code you can do the following:

configatron.email # => "me@example.com"
configatron.database.url # => "postgres://localhost/foo"

Voila! Simple as can be.

Now you're saying, what if I want to have a 'default' set of options, but then override them later, based on other information? Simple again. Let's use our above example. We've configured our database.url option to be postgres://localhost/foo. The problem with that is that is our production database url, not our development url. Fair enough, all you have to do is redeclare it:

configatron.database.url = "postgres://localhost/foo_development"

becomes:

configatron.email # => "me@example.com"
configatron.database.url # => "postgres://localhost/foo_development"

Notice how our other configuration parameters haven't changed? Cool, eh?

Hash/YAML

You can configure Configatron from a hash as well (this is particularly useful if you'd like to have configuration files):

configatron.configure_from_hash(email: {pop: {address: 'pop.example.com', port: 110}}, smtp: {address: 'smtp.example.com'})

configatron.email.pop.address # => 'pop.example.com'
configatron.email.pop.port # => 110
# and so on...

Method vs hash access

As a note, method (configatron.foo) access will be shadowed by public methods defined on the configatron object. (The configatron object descends from BasicObject and adds a few methods to resemble the Hash API and to play nice with puts, so it should have a pretty bare set of methods.)

If you need to use keys that are themselves method names, you can just use hash access (configatron['foo']).

Namespaces

The question that should be on your lips is what I need to have namespaced configuration parameters. It's easy! Configatron allows you to create namespaces.

configatron.website_url = "http://www.example.com"
configatron.email.pop.address = "pop.example.com"
configatron.email.pop.port = 110
configatron.email.smtp.address = "smtp.example.com"
configatron.email.smtp.port = 25

configatron.to_h # => {:website_url=>"http://www.example.com", :email=>{:pop=>{:address=>"pop.example.com", :port=>110}, :smtp=>{:address=>"smtp.example.com", :port=>25}}}

Configatron allows you to nest namespaces to your hearts content! Just keep going, it's that easy.

Of course you can update a single parameter n levels deep as well:

configatron.email.pop.address = "pop2.example.com"

configatron.email.pop.address # => "pop2.example.com"
configatron.email.smtp.address # => "smtp.example.com"

Configatron will also let you use a block to clean up your configuration. For example the following two ways of setting values are equivalent:

configatron.email.pop.address = "pop.example.com"
configatron.email.pop.port = 110

configatron.email.pop do |pop|
  pop.address = "pop.example.com"
  pop.port = 110
end

Temp Configurations

Sometimes in testing, or other situations, you want to temporarily change some settings. You can do this with the temp method (only available on the top-level configatron RootStore):

configatron.one = 1
configatron.letters.a = 'A'
configatron.letters.b = 'B'
configatron.temp do
  configatron.letters.b = 'bb'
  configatron.letters.c = 'c'
  configatron.one # => 1
  configatron.letters.a # => 'A'
  configatron.letters.b # => 'bb'
  configatron.letters.c # => 'c'
end
configatron.one # => 1
configatron.letters.a # => 'A'
configatron.letters.b # => 'B'
configatron.letters.c # => {}

Delayed and Dynamic Configurations

There are times when you want to refer to one configuration setting in another configuration setting. Let's look at a fairly contrived example:

configatron.memcached.servers = ['127.0.0.1:11211']
configatron.page_caching.servers = configatron.memcached.servers
configatron.object_caching.servers = configatron.memcached.servers

if Rails.env == 'production'
  configatron.memcached.servers = ['192.168.0.1:11211']
  configatron.page_caching.servers = configatron.memcached.servers
  configatron.object_caching.servers = configatron.memcached.servers
elsif Rails.env == 'staging'
  configatron.memcached.servers = ['192.168.0.2:11211']
  configatron.page_caching.servers = configatron.memcached.servers
  configatron.object_caching.servers = configatron.memcached.servers
end

Now, we could've written that slightly differently, but it helps to illustrate the point. With Configatron you can create Delayed and Dynamic settings.

Delayed

With Delayed settings execution of the setting doesn't happen until the first time it is executed.

configatron.memcached.servers = ['127.0.0.1:11211']
configatron.page_caching.servers = Configatron::Delayed.new {configatron.memcached.servers}
configatron.object_caching.servers = Configatron::Delayed.new {configatron.memcached.servers}

if Rails.env == 'production'
  configatron.memcached.servers = ['192.168.0.1:11211']
elsif Rails.env == 'staging'
  configatron.memcached.servers = ['192.168.0.2:11211']
end

Execution occurs once and after that the result of that execution is returned. So in our case the first time someone calls the setting configatron.page_caching.servers it will find the configatron.memcached.servers setting and return that. After that point if the configatron.memcached.servers setting is changed, the original settings are returned by configatron.page_caching.servers.

Dynamic

Dynamic settings are very similar to Delayed settings, but with one big difference. Every time you call a Dynamic setting is executed. Take this example:

configatron.current.time = Configatron::Dynamic.new {Time.now}

Each time you call configatron.current.time it will return a new value to you. While this seems a bit useless, it is pretty useful if you have ever changing configurations.

Reseting Configurations

In some testing scenarios, it can be helpful to restore Configatron to its default state. This can be done with:

configatron.reset!

Checking keys

Even if parameters haven't been set, you can still call them, but you'll get a Configatron::Store object back. You can use .has_key? to determine if a key already exists.

configatron.i.dont.has_key?(:exist) # => false

(key)!

You can also append a ! to the end of any key. If the key exists it will return it, otherwise it will raise a Configatron::UndefinedKeyError.

configatron.a.b = 'B'
configatron.a.b # => 'B'
configatron.a.b! # => 'B'
configatron.a.b.c! # => raise Configratron::UndefinedKeyError

Kernel

The configatron "helper" method is stored in the Kernel module. You can opt-out of this global monkey-patching by requiring configatron/core rather than configatron. You'll have to set up your own Configatron::RootStore object.

Example:

require 'configatron/core'

store = Configatron::RootStore.new
store.foo = 'FOO'

store.to_h #= {foo: 'FOO'}

Locking

Once you have setup all of your configurations you can call the lock! method to lock your settings and raise an error should anyone try to change settings or access an unset setting later.