def config(name)
      config = configs.select {|config| config.name == name.to_s }.first
      raise "No such config #{name}, available configs are #{configs.map {|c| c.name}.join(', ')}" if config.nil?
      yield config if block_given?
      config
    end
def config(name)
      config = configs.select {|config| config.name == name.to_s }.first
      raise "No such config #{name}, available configs are #{configs.map {|c| c.name}.join(', ')}" if config.nil?
      yield config if block_given?
      config
    end
Return a specific build configuration.

 @note an exception is raised if no configuration matches the specified name.

 @param [String] name of a configuration to return

 @return [BuildConfiguration] a specific build configuration that
   matches the specified name.