{"width":"100%","blog_title":"...ing logging 4.0","description":"\u96c6\u4e2d\u9023\u8f09\u300c\u30af\u30e9\u30b9\u9593\u4f9d\u5b58\u95a2\u4fc2\u306e\u9664\u53bb\u300d\u3092\u66f8\u3044\u3066\u3044\u3066\u601d\u3063\u305f\u3053\u3068\uff0e \u5171\u5909\u306e\u623b\u308a\u5024\u578b\u3092\u30b5\u30dd\u30fc\u30c8\u3057\u3066\u3044\u308bD\u8a00\u8a9e\u3067\u306f\uff0c\u6b21\u306e\u3088\u3046\u306b\uff1b class A {} class B : A {} class Foo { A hoge() { return new A; } } class Bar : Foo { B hoge() { return new B; } // override with covariant return type } \u623b\u308a\u5024\u578b\u304c\u7570\u306a\u308b Bar.hoge() \u3067 Foo.hoge() \u3092\u30aa\u30fc\u30d0\u30fc\u30e9\u30a4\u30c9\u3059\u308b\u3053\u3068\u304c\u8a31\u3055\u308c\u3066\u3044\u307e\u3059\uff0e \u300c\u305d\u308c\u306a\u3089\u300d\u3068\u601d\u3044\uff0c\u6b21\u306e\u30b3\u30fc\u30c9\u3092\u8a66\u3057\u3066\u307f\u307e\u3057\u305f\uff0e import s\u2026","height":"190","image_url":null,"provider_name":"Hatena Blog","author_name":"haru-s","published":"2007-06-28 15:53:06","url":"https://haru-s.hatenablog.com/entry/20070628/1183013586","author_url":"https://blog.hatena.ne.jp/haru-s/","html":"<iframe src=\"https://hatenablog-parts.com/embed?url=https%3A%2F%2Fharu-s.hatenablog.com%2Fentry%2F20070628%2F1183013586\" title=\" \u5171\u5909\u306e\u623b\u308a\u5024\u578b (Covariant Return Type) \u306e\u62e1\u5f35 - ...ing logging 4.0\" class=\"embed-card embed-blogcard\" scrolling=\"no\" frameborder=\"0\" style=\"display: block; width: 100%; height: 190px; max-width: 500px; margin: 10px 0px;\"></iframe>","provider_url":"https://hatena.blog","categories":["D\u8a00\u8a9e"],"version":"1.0","title":" \u5171\u5909\u306e\u623b\u308a\u5024\u578b (Covariant Return Type) \u306e\u62e1\u5f35","blog_url":"https://haru-s.hatenablog.com/","type":"rich"}