Sketches of Configuration API

gistfile1.rb

class Thing
  include Configured
  
  setting :some_setting
  setting :other_setting
end

class Configuration
  def some_setting
    'foo'
  end
  
  def other_setting
    'bar'
  end
end

# Example 1: Configuring with explicit config object
config = Configuration.new
thing = Thing.new
thing.configure(config)
thing.some_setting # => 'foo'
thing.other_setting # => 'bar'

# Example 2: Configuring with default config object
thing = Thing.new
thing.configure # no arg. raises an error.

# add 'default' method to configuration object
class Configuration
  def default
    self.instance # or whatever means of getting an instance
  end
end

thing = Thing.new
thing.configure # uses Configuration.default

# Example 3: Get setting names
Thing.settings # => [:some_setting, :other_setting]

# Example 4: Get settings
thing = Thing.new
thing.settings # => { :some_setting => nil, :other_setting => nil }
thing.configure
thing.settings # => { :some_setting => 'foo', :other_setting => 'bar' }

# Example 5: Change the configuration source
class SomeConfiguration
  def other_setting
    'blah'
  end
end

class Thing
  include Configured
  configuration SomeConfiguration
  
  setting :some_setting
  setting :other_setting
end

thing = Thing.new
thing.configure
thing.other_setting # => 'blah'

# Example 6: Use the configuration API directly
class OtherConfiguration
  def other_setting
    'blaz'
  end
end

thing = Thing.new
config = OtherConfiguration.new # or whatever means of creating an instance
config.configure(thing)
thing.some_setting # => nil # provides (pushes) only those values it knows about
thing.other_setting # => 'blaz'

# Example 7: Errors when object cannot be completely configured when pulling settings from a configuration object
class FooConfiguration
  def some_setting
    'foo'
  end
end

class Thing
  include Configured
  configuration FooConfiguration
  
  setting :some_setting
  setting :other_setting
end

# Example 8: Configuring with explicit config object
thing = Thing.new
thing.configure
# => Configuration Error, "'other_setting' is not configured'