matching.rb

class Base
  DEFAULT_PROC = -> () {}
  
  def initialize(api_key, connection_class = External::Service, builder = -> (klass, key) { klass.new(key) })
    @api_key = api_key
    @builder = builder
    @connection_class = connection_class
  end
  
  def execute(&block)
    begin
      [:ok, yield(connection)]
    rescue Service::Error => e
      [:err, e.message]
    end
  end
  
  private
  
  def connection
    @builder.call(@connection_class, @api_key)
  end
end

class Finder < Base
  def query(endpoint)
    key, value = execute { |connection| connection.get(endpoint) }
    case [key, value.class]
    when [:ok, Hash]    then value['response']
    when [:err, String] then value
    else raise 'something happened I dont understand'
    end
  end
end


# Finder.new('my key').query('/double/rainbow') #=> "OMG IN THE SKY"