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
自訂的例外類別
你可以擴充任何的標準例外類別來定義你自己的例外類別。通常，這樣的
子類別除了加上一個 docstring 以外不會做任何事：
class InvalidAttribute(AttributeError):
"""Used to indicate attributes that could never be valid"""
任何空的類別或函式都應該有一個
docstring
，
而非
pass
如前面的「pass 述句」中所涵蓋的，你不需要一個
pass
述句來構成一個類別的主體，只要有 docstring（你應該永
遠都寫，以記載類別的用途）就足以讓 Python 滿意。所
有「空」類別（不管它們是不是例外類別）的最佳實務做
法，就跟所有「空」函式一樣，都是帶有一個 docstring，
而非
pass
述句。
根據
try/except
的語意，提出像
InvalidAttribute
這樣的自訂例外類別幾
乎等同於提出它的標準例外超類別
AttributeError
。處理
AttributeError
的
任何
except
子句也都能處理
InvalidAttribute
。此外，知道你自訂例外類
別
InvalidAttribute
的客戶端程式碼也能特別處理它，而不用應付不準備
處理的其他 AttributeError 情況。舉例來說：
class SomeFunkyClass(object):
"""much hypothetical functionality snipped"""
def ...
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I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
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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.