September 2014
Intermediate to advanced
332 pages
6h 48m
Japanese
Content preview from Python文法詳解
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286
第 7 章 データ型とプロトコル
のように、インデックス値として浮動小数点数などを指定しても、エラーとならずに
sequence[0]
が実行されてしまうためです。
同様に、
bin()
や
hex()
など、整数のみが対象となる組み込み関数も、
__int__()
メソッドで
はなく、
__index__()
メソッドを使って整数値を取得します。
7.8.8
ハッシュ値
表
7-12
ハッシュ値
式 メソッド
map[obj], hash(obj) __hash___(self)
オブジェクトのハッシュ値を、整数値で返します。
__hash__()
を実装するオブジェクトはハッシュ可能と呼ばれ、以下の条件を満たさなければな
りません。
• 2
つのオブジェクトが
obj1 == obj2
なら、
hash(obj1) == hash(obj2)
が成立するように、
__eq__()
メソッドを実装しなければなりません。
•
オブジェクトのハッシュ値は、オブジェクトが作られてから削除されるまで、変化しては
なりません。
ハッシュ可能なオブジェクトは、辞書のキーや集合型の要素として登録できます。
7.8.9
文字列化・バイト列化
表
7-13
文字列化・バイト列化
式 メソッド
repr(obj) __repr__(self)
str(obj) __str__(self)
bytes(obj) __bytes__(self)
format(obj, 'format_spec') __format__(self, format_spec)
オブジェクトから、文字列やバイト列に変換する場合に呼び出されます。 ...
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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.