Ruby:两次拯救相同的错误类型

Question

是否可以在 ruby​​ 中多次挽救相同的错误类型？我需要像这样使用 Koala facebook API 库:

begin
  # Try with user provided app token
  fb = Koala::Facebook::API.new(user_access_token)
  fb.put_connections(user_id, {}) # TODO
rescue AuthenticationError
  # User access token has expired or is fake
  fb = Koala::Facebook::API.new(APP_FB_TOKEN)
  fb.put_connections(user_id, {}) # TODO
rescue AuthenticationError
  # User hasn't authed the app on facebook
  puts "Could not authenticate"
  next
rescue => e
  puts "Error when posting to facebook"
  puts e.message
  next
end

如果没有办法两次挽救同一个错误，是否有更好的推理方法？

Answer 1

您应该将其重构为两个单独的方法 - 一个处理异常的“安全”authenticate 方法，和一个引发异常的“不安全”authenticate! 方法。 authenticate 应该根据 authenticate!

来定义

下面是一个如何执行此操作的示例，其中包含重试实现。

编辑:重构使重试独立于 authenticate 方法。

def authenticate!
  fb = Koala::Facebook::API.new(user_access_token)
  fb.put_connections(user_id.to_s, )
end

def authenticate
  authenticate!
rescue => e
  warn "Error when posting to facebook: #{e.message}"
end

# @param [Integer] num_retries number of times to try code
def with_retries(num_retries=2)
  yield
rescue AuthenticationError
  # User hasn't authed the app on facebook
  puts "Could not authenticate"
  # Retry up to twice
  (num_retries-=1) < 1 ? raise : retry
end

# Authenticate safely, retrying up to 2 times
with_retries(2) { authenticate }

# Authenticate unsafely, retrying up to 3 times
with_retries(2) { authenticate! }