ruby script/plugin install git://github.com/lukeredpath/simpleconfig.git

Getting started
===============
The plugin comes with a rake task to get you up and running quickly, so start by running that.

$ rake simple_config:setup

This will create a config/settings folder and a blank settings file for each of the main Rails environments. It will also create a copy of the SimpleConfig initializer in config/initializers/configuration.rb.

Now, if you open up the configuration.rb initializer, you will see something like this:

SimpleConfig.for :application do

  # your app configuration here

  load File.join(RAILS_ROOT, 'config', "settings", "#{RAILS_ENV}.rb"), :if_exists? => true
  load File.join(RAILS_ROOT, 'config', "settings", "local.rb"),        :if_exists? => true

end

This is where you can set any configuration variables that are required across all Rails environments. The load method works just like Ruby’s built-in load method, except the contents of the file it loads are evaluated within the context of the SimpleConfig.for block. The :if_exists? flag, when set to true, means that the file will only be loaded if it exists, otherwise it will simply be ignored.

Variables can be overwritten, and are defined in the order that they are loaded, so you can set up default values in the above file and override them in the environment files.

As well as loading a settings file for your current Rails environment, a file called “local.rb” is loaded which is designed as a place for you to override variables specific to your own development environment—you can just keep a copy of this locally without having to check it into your version control system2.

Setting variables
=================
Setting variables is simple and will be familiar to anybody who has used Capistrano. Whether in your main SimpleConfig.for block in configuration.rb, or one of your external settings files, use the set method:

SimpleConfig.for :application do
  set :my_variable, 'hello world'
end

SimpleConfig also supports a form of namespacing that allows you to group logical sets of variables together:

SimpleConfig.for :application do
  group :awesome_stuff do
    set :my_variable, 'hello world'
  end
end

Both the set and load methods are available within group blocks and files loaded inside groups will be evaluated in the context of that group.

Whilst I’d recommend not nesting your groups more than one-level, there is no limit on how deep they can be nested.

Accessing your configuration
======================

SimpleConfig allows you set as many separate configurations as you like using the SimpleConfig.for method, which takes a symbol representing the configuration name, although most people will just create a single “application” config as above. To access this config from anywhere in your application, you can also use SimpleConfig.for method without a block, which always returns the named configuration object.

It is worth pointing out that SimpleConfig.for provides an almost singleton-style access to a particular named config. Calling SimpleConfig.for with a block a second time for a particular named configuration will simply extend the existing configuration, not overwrite it.

Once you have a reference to your configuration object, you can access variables using method access. Given the above example, :my_variable would be accessed in the following way:

config = SimpleConfig.for(:application)
config.my_variable # => "hello world"

Accessing grouped variables works as you would expect:

config = SimpleConfig.for(:application)
config.awesome_stuff.my_variable # => "hello world" 

Using your configuration in your Rails app
================================
The plugin provides a convenient mixin for your ApplicationController to make configuration access as simple as possible. Assuming a configuration called “application” (as in the above examples), it defines a config method which can be used in any of your controllers. It also defines this as a method as a view helper using the Rails helper_method macro so you can access configuration data in your views.

Note – there is no direct way of accessing your configuration variables in your models other than making a direct call to SimpleConfig.for. I’d recommend designing your models in such a way that configuration data can be passed into them at runtime as method arguments by your controller to avoid coupling your model to SimpleConfig.

To use the mixin, simply include it in your ApplicationController:

class ApplicationController < ActionController::Base
  include SimpleConfig::ControllerMixin
end

Then in your controllers:

class MyController < ApplicationController
  def index
    render :text => config.my_config_variable
  end
end

There is currently no advanced documentation for this plugin.