MyGem.configure block

We recently made some enhancements to Clearance. One of those was to replace a manual process of the developer setting constants in their Rails environment files with a configuration block that could be used in config/initializers/clearance.rb.

I liked the way Hoptoad does it and wanted to implement the same pattern:

HoptoadNotifier.configure do |config|
  config.api_key = 'your_key_here'
end

So let’s implement:

module Clearance
  class << self
    attr_accessor :configuration
  end

  def self.configure
    self.configuration ||= Configuration.new
    yield(configuration)
  end

  class Configuration
    attr_accessor :mailer_sender

    def initialize
      @mailer_sender = 'donotreply@example.com'
    end
  end
end

We have a configure class method that stores a Configuration object inside the Clearance module.

Anything application developers can set from their configure block is an attr_accessor on the Configuration class.

side note - I used the name mailer_sender to match the Devise API.

So now, we can have a config/initializers/clearance.rb:

Clearance.configure do |config|
  config.mailer_sender = 'donotreply@example.com'
end

Easy for the application developer to understand. Cleaner implementation internally:

Clearance.configuration.mailer_sender

As an added bonus, in the library’s tests, we can set configuration attributes without worrying about undefining constants:

Clearance.configuration.mailer_sender= 'new.email@example.com'

Yay.