January 2018
Intermediate to advanced
856 pages
17h 17m
Chinese
Content preview from Python 技術手冊 第三版
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第 5 章 例外
為自訂例外使用多重繼承
每當你必須決定是要提出一個特定的標準例外，例如
AttributeError
，還是你在你模組中定義的一個自訂例外，
那就考慮這種多重繼承的做法，它能讓你兩者兼顧。請確
保你有在說明文件中清楚記載你模組的這個層面，因為這
個技巧並沒有廣泛被使用，你模組的使用者可能沒有如此
預期，除非你清楚且明確的記錄在文件中。
標準程式庫中所使用的其他例外
Python 標準程式庫中的許多模組都定義有它們自己的例外類別，它們與你
自己的模組可以定義的自訂例外類別有相同的效果。一般來說，這種標準
程式庫模組中的所有函式，除了標準階層架構（涵蓋於前面的「標準例外
類別」）中的例外，也可以提出這種類別的例外。舉例來說，在 v2 中，模
組
socket
提供了類別
socket.error
，它直接衍生自內建類別
Exception
，還
有
error
的數個子類別
sslerror
、
timeout
、
gaierror
與
herror
。
模組
socket
中的所有函式與方法，除了標準例外之外，也可以提出類別
socket.error
及其子類別的例外。我們會在本書其餘部分的各處涵蓋這種
例外類別的主要案例，在提供它們的標準程式庫模組的章節中。
錯誤檢查策略
支援例外的多數程式語言只會在少數情況下提出例外。Python 所強調的重
點則不同。Python 會在例外使得程式更為簡單而且更穩健的時候運用它
們，即使那會讓例外變得相當頻繁。
LBYL vs. EAFP
其他語言中一個常見的慣用語（idiom），有時叫做「
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I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.