March 2018
Beginner to intermediate
624 pages
16h 10m
Japanese
Content preview from Head First Python 第2版 ―頭とからだで覚えるPythonの基本
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.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.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.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.
__init__
は魔法
324
8
章
あの時は、すべてのダンダーを無視するように言いました。ここでその理由を明らかにし
ましょう。ダンダーはクラスの標準的な振る舞いにアクセスできるようにするものです。
オーバーライドしない限り、この標準的な振る舞いはクラス
object
で実装されていま
す。
object
クラスはインタプリタに組み込まれているので、他のすべてのクラス（自分の
書いたクラスも含む）は自動的に
object
クラスを継承します。これは
OOP
用語で言うと、
object
が提供するダンダーメソッドをクラスでそのまま利用したり、または（独自の実装
を提供することで）必要に応じてオーバーライドできるということです。
必要がなければ、
object
メソッドをオーバーライドしなくても構いません。しかし、例
えばクラスから生成したオブジェクトを等価演算子（
==
）と一緒に使う場合の動作を指定し
たい場合には、
__eq__
メソッドの独自のコードを書きます。オブジェクトを大なり演算子
（
>
）と一緒に使う場合の動作を指定したい場合には、
__ge__
メソッドをオーバーライドし
ます。また、オブジェクトに関連する属性を初期化したいときには、
__init__
メソッドを
使います。
object
が提供するダンダーはとても便利で、特殊メソッドと呼ばれます。
つまり、下のような
def
行を使ってクラスでメソッドを定義すると、クラスから新たな
オブジェクトを生成するたびにインタプリタはこの
__init__
メソッドを呼び出します。
この
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Read now
Unlock full access
More than 5,000 organizations count on O’Reilly
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
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.
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.