class RSpec::Core::Configuration

def self.add_setting(name, opts={})
  raise "Use the instance add_setting method if you want to set a default" if opts.has_key?(:default)
  if opts[:alias]
    RSpec.warn_deprecation <<-MESSAGE
lias option to add_setting is deprecated. Use :alias_with on the original setting instead.
 from #{caller(0)[4]}
E
    alias_method name, opts[:alias]
    alias_method "#{name}=", "#{opts[:alias]}="
    define_predicate_for name
  else
    attr_writer name
    eval <<-CODE
      def #{name}
        value_for(#{name.inspect}, defined?(@#{name}) ? @#{name} : nil)
      end
    CODE
    define_predicate_for name
  end
  if opts[:alias_with]
    [opts[:alias_with]].flatten.each do |alias_name|
      alias_method alias_name, name
      alias_method "#{alias_name}=", "#{name}="
      define_predicate_for alias_name
    end
  end
end