=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!
 
==Installation
 
Installation of Configatron is easy, as it is just a RubyGem:
 
  $ sudo gem install configatron
 
If you'd like to live on the bleedin' edge you can install the development version from GitHub:
 
  $ sudo gem install markbates-configatron --source=http://gems.github.com
 
Once installed you just need to require it:
 
  require 'configatron'
 
==Examples
 
===Simple
 
  configatron.email = 'me@example.com'
  configatron.database_url = "postgres://localhost/mack_framework_rocks"
 
Now, anywhere in your code you can do the following:
 
  configatron.email # => "me@example.com"
  configatron.database_url # => "postgres://localhost/mack_framework_rocks"
 
Viola! 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 <tt>database_url</tt> option to be <tt>postgres://localhost/mack_framework_rocks</tt>. 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/mack_framework_rocks_development"
 
becomes:
 
  configatron.email # => "me@example.com"
  configatron.database_url # => "postgres://localhost/mack_framework_rocks_development"
 
Notice how our other configuration parameters haven't changed? Cool, eh?
 
===Hash/YAML
 
You can configure configatron from a hash as well:
 
  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...
 
Notice how they're all namespaced for your as well. The same holds true for YAML files:
 
  configatron.configure_from_yaml('/path/to/file.yml')
 
===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.mackframework.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
 
becomes:
 
  configatron.email.pop.address # => "pop.example.com"
  configatron.email.smtp.address # => "smtp.example.com"
  configatron.website_url # => "http://www.mackframework.com"
 
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"
 
===Temp Configurations
 
Sometimes in testing, or other situations, you want to temporarily change some settings. You can do this with the <tt>temp</tt> method:
 
  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 # => nil
 
You can also pass in an optional Hash to the <tt>temp</tt>:
 
  configatron.one = 1
  configatron.letters.a = 'A'
  configatron.letters.b = 'B'
  configatron.temp(:letters => {:b => 'bb', :c => 'c'}) do
    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 # => nil
 
===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 <code>Delayed</code> and <code>Dynamic</code> settings. 
 
====Delayed
 
With <code>Delayed</code> 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 <code>configatron.page_caching.servers</code> it will find the <code>configatron.memcached.servers</code> setting and return that. After that point if the <code>configatron.memcached.servers</code> setting is changed, the original settings are returned by <code>configatron.page_caching.servers</code>.
 
====Dynamic
 
<code>Dynamic</code> settings are very similar to <code>Delayed</code> settings, but with one big difference. Every time you call a <code>Dynamic</code> setting is executed. Take this example:
 
  configatron.current.time = Configatron::Dynamic.new {Time.now}
 
Each time you call <code>configatron.current.time</code> it will return a new value to you. While this seems a bit useless, it is pretty useful if you have ever changing configurations.
 
===Misc.
 
Even if parameters haven't been set, you can still call them, but you'll get a <tt>Configatron::Store</tt> object back. The Configatron::Store class, however, will respond true to <tt>.nil?</tt> if there are no parameters configured on it.
 
  configatron.i.dont.exist.nil? # => true
  configatron.i.dont.exist # => Configatron::Store
 
If you want to get back an actual <tt>nil</tt> then you can use the <tt>retrieve</tt> method:
 
  configatron.i.do.exist = [:some, :array]
  configatron.i.dont.retrieve(:exist, nil) # => nil
  configatron.i.do.retrieve(:exist, :foo) # => [:some, :array]
 
You can set 'default' values for parameters. If there is already a setting, it won't be replaced. This is useful if you've already done your 'configuration' and you call a library, that needs to have parameters set. The library can set its defaults, without worrying that it might have overridden your custom settings.
 
  configatron.set_default(:name, 'Mark Bates')
  configatron.name # => 'Mark Bates'
  configatron.set_default(:name, 'Me')
  configatron.name # => 'Mark Bates'
 
Enjoy!
 
==Contact
 
Please mail bugs, suggestions and patches to "development@metabates.com":mailto:development@metabates.com
 
On the web at: "http://www.metabates.com":http://www.metabates.com