{"id":23493,"date":"2017-03-08T12:50:54","date_gmt":"2017-03-08T03:50:54","guid":{"rendered":"http:\/\/arison.jp\/blog\/?p=23493"},"modified":"2018-07-20T00:26:57","modified_gmt":"2018-07-19T15:26:57","slug":"null-and-antony-hoare","status":"publish","type":"post","link":"https:\/\/arison.jp\/blog\/2017\/03\/08\/null-and-antony-hoare\/","title":{"rendered":"Null \u3092\u7523\u307f\u51fa\u3057\u305f\u30a2\u30f3\u30c8\u30cb\u30fc\u30fb\u30db\u30fc\u30a2\u6c0f"},"content":{"rendered":"<p>1\u304b\u30899\u306e\u6570\u5b57\u3092\u767a\u898b\u3057\u305f\u30a2\u30e9\u30d3\u30a2\u4eba\u3002<br \/>\n0\u3092\u767a\u898b\u3057\u305f\u30a4\u30f3\u30c9\u4eba\u3002<br \/>\nNull \u3092\u7523\u307f\u51fa\u3057\u305f\u30a2\u30f3\u30c8\u30cb\u30fc\u30fb\u30db\u30fc\u30a2\u6c0f\u3002<\/p>\n<p>Null \u306e\u5b58\u5728\u306b\u5f8c\u6094\u3057\u3066\u3044\u308b\u30db\u30fc\u30a2\u6c0f\u3002<br \/>\n\u7bb1\u306e\u4e2d\u306e\u30ea\u30f3\u30b4\u306e\u6570\u3092\u8abf\u3079\u305f\u3068\u304d\u306b\u3001\u30ea\u30f3\u30b4\u304c0\u500b\u306a\u306e\u3068\u7bb1\u304c\u306a\u3044(Null)\u306f\u9055\u3046\u3053\u3068\u3060\u3051\u3069\u3055\u3002<br \/>\n\u300c\uff76\uff9e\uff82\u300d\u3068\u6bb4\u308a\u305f\u304f\u306a\u308b<br \/>\n<!--more--><\/p>\n<p>1\u304b\u30899\u306e\u6570\u5b57\u3092\u767a\u898b\u3057\u305f\u30a2\u30e9\u30d3\u30a2\u4eba\u3001\u307e\u305a\u3001\u6570\u5b57\u3092\u767a\u898b\u3057\u305f\u3053\u3068\u304c\u3059\u3054\u3044\u3068\u601d\u3046\u3002<br \/>\n\u3053\u308c\u304c\u306a\u3044\u3068\u6570\u3048\u308b\u3053\u3068\u3059\u3089\u51fa\u6765\u306a\u304b\u3063\u305f\u308f\u3051\u3060\u3057\u306d\u3002<br \/>\n\u307e\u3042\u3001\u3067\u3082\u3001\u6570\u3048\u308b\u3053\u3068\u51fa\u6765\u306a\u3044\u3068\u4e0d\u4fbf\u3060\u3057\u3001\u30a2\u30e9\u30d3\u30a2\u4eba\u3067\u306f\u306a\u304f\u3066\u3082\u4ed6\u306e\u8ab0\u304b\u304c\u898b\u3064\u3051\u308b\u3053\u3068\u306f\u51fa\u6765\u305f\u3093\u3060\u308d\u3046\u306d\u3002<\/p>\n<p>\u3067\u30010\u3092\u767a\u898b\u3057\u305f\u30a4\u30f3\u30c9\u4eba\u3002<br \/>\n0\uff1d\u7121\u3068\u3044\u3046\u610f\u5473\u3067\u306f\u3001\u7121\u3044\u3082\u306e\u306b\u6c17\u304c\u3064\u304f\u306e\u306f\u30a4\u30f3\u30c9\u4eba\u3063\u307d\u3044\u3002<br \/>\n\u30a4\u30f3\u30c9\u4eba\u3068\u3044\u3046\u3088\u308a\u306f\u3001\u6771\u6d0b\u3068\u3044\u3046\u304b\u4ecf\u6559\u3068\u3044\u3046\u304b\u30fb\u30fb\u30fb<br \/>\n\u7121\u3068\u304b\u7a7a\u3068\u304b\u3044\u3046\u3082\u306e\u3001\u76ee\u306b\u898b\u3048\u306a\u3044\u3082\u306e\u3001\u5b58\u5728\u3057\u306a\u3044\u3082\u306e\u306b\u7740\u76ee\u3057\u3066\u3044\u308b\u3068\u3044\u3046\u70b9\u3067\u306f\u30a4\u30f3\u30c9\u4eba\u306f\u6d41\u77f3\u3063\u3066\u3053\u3068\u306a\u3093\u3060\u308d\u3046\u306a\u3002<\/p>\n<p>\u3067\u3001\u3055\u3089\u306bNull\u3002<br \/>\n\u8ab0\u304c\u767a\u898b\u3057\u305f\u304b\u81ea\u5206\u306f\u6700\u8fd1\u307e\u3067\u77e5\u3089\u306a\u304b\u3063\u305f\u3093\u3060\u3051\u3069\u3001\u30a2\u30f3\u30c8\u30cb\u30fc\u30fb\u30db\u30fc\u30a2\u6c0f\u304c\u8a95\u751f\u3055\u305b\u305f\u3089\u3057\u3044\u3002<br \/>\n\u30c1\u30e3\u30fc\u30eb\u30ba\u30fb\u30a2\u30f3\u30c8\u30cb\u30fc\u30fb\u30ea\u30c1\u30e3\u30fc\u30c9\u30fb\u30db\u30fc\u30a2\uff08Charles Antony Richard Hoare\uff09\u6c0f\u306f\u30af\u30a4\u30c3\u30af\u30bd\u30fc\u30c8\u3067\u3082\u6709\u540d\u306a\u65b9\u3002<br \/>\n26\u6b73\u3067\u30af\u30a4\u30c3\u30af\u30bd\u30fc\u30c8\u3092\u958b\u767a\u3057\u305f\u4eba\u306a\u3093\u3060\u304b\u3089\u3001\u534a\u7aef\u306a\u3044\u3002<\/p>\n<p>\u3053\u3093\u306a\u540d\u8a00\u3082\u6b8b\u3057\u3066\u3044\u308b\u3002<\/p>\n<blockquote><p>\u300c\u30bd\u30d5\u30c8\u30a6\u30a7\u30a2\u3092\u8a2d\u8a08\u3059\u308b\u306b\u306f\u30012\u901a\u308a\u306e\u65b9\u6cd5\u304c\u3042\u308b\u3002<br \/>\n1\u3064\u306f\u3001\u3068\u3066\u3082\u30b7\u30f3\u30d7\u30eb\u306b\u8a2d\u8a08\u3057\u3066\u3001\u660e\u3089\u304b\u306b\u6b20\u9665\u304c\u306a\u3044\u3088\u3046\u306b\u3059\u308b\u3053\u3068\u3002<br \/>\n\u3082\u30461\u3064\u306f\u3001\u3068\u3066\u3082\u8907\u96d1\u306b\u8a2d\u8a08\u3057\u3066\u660e\u3089\u304b\u306a\u6b20\u9665\u304c\u306a\u3044\u3088\u3046\u306b\u3059\u308b\u3053\u3068\u3060\u3002\u524d\u8005\u306e\u65b9\u304c\u306f\u308b\u304b\u306b\u56f0\u96e3\u3067\u3042\u308b\u3002\u300d<\/p><\/blockquote>\n<p>\u3067\u3001\u30a2\u30f3\u30c8\u30cb\u30fc\u30fb\u30db\u30fc\u30a2\u6c0f\u306fNull\u3092\u7523\u3093\u3060\u3053\u3068\u306b\u3064\u3044\u3066\u5f8c\u6094\u3092\u3057\u3066\u3044\u308b\u3002<\/p>\n<blockquote><p>\u305d\u308c\u306f10\u5104\u30c9\u30eb\u306b\u3082\u76f8\u5f53\u3059\u308b\u79c1\u306e\u8aa4\u308a\u3060\u3002<br \/>\nnull\u53c2\u7167\u3092\u767a\u660e\u3057\u305f\u306e\u306f1965\u5e74\u306e\u3053\u3068\u3060\u3063\u305f\u3002<br \/>\n\u5f53\u6642\u3001\u79c1\u306f\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u6307\u5411\u8a00\u8a9e (ALGOL W) \u306b\u304a\u3051\u308b\u53c2\u7167\u306e\u305f\u3081\u306e\u5305\u62ec\u7684\u578b\u30b7\u30b9\u30c6\u30e0\u3092\u8a2d\u8a08\u3057\u3066\u3044\u305f\u3002<br \/>\n\u76ee\u6a19\u306f\u3001\u30b3\u30f3\u30d1\u30a4\u30e9\u3067\u306e\u81ea\u52d5\u30c1\u30a7\u30c3\u30af\u3067\u5168\u3066\u306e\u53c2\u7167\u304c\u5b8c\u5168\u306b\u5b89\u5168\u3067\u3042\u308b\u3053\u3068\u3092\u4fdd\u8a3c\u3059\u308b\u3053\u3068\u3060\u3063\u305f\u3002<br \/>\n\u3057\u304b\u3057\u3001\u79c1\u306f\u5358\u306b\u305d\u308c\u304c\u5bb9\u6613\u3060\u3068\u3044\u3046\u3060\u3051\u3067\u3001\u7121\u52b9\u306a\u53c2\u7167\u3092\u542b\u3081\u308b\u8a98\u60d1\u306b\u62b5\u6297\u3067\u304d\u306a\u304b\u3063\u305f\u3002<br \/>\n\u3053\u308c\u306f\u3001\u5f8c\u306b\u6570\u3048\u5207\u308c\u306a\u3044\u904e\u3061\u3001\u8106\u5f31\u6027\u3001\u30b7\u30b9\u30c6\u30e0\u30af\u30e9\u30c3\u30b7\u30e5\u3092\u5f15\u304d\u8d77\u3053\u3057\u3001\u904e\u53bb40\u5e74\u9593\u306710\u5104\u30c9\u30eb\u76f8\u5f53\u306e\u82e6\u75db\u3068\u640d\u5bb3\u3092\u5f15\u304d\u8d77\u3053\u3057\u305f\u3068\u307f\u3089\u308c\u308b\u3002<\/p><\/blockquote>\n<p>\u539f\u6587\u306f\u3053\u3061\u3089<\/p>\n<blockquote><p>I call it my billion-dollar mistake.<br \/>\n It was the invention of the null reference in 1965.<br \/>\n At that time, I was designing the first comprehensive type system for references in an object oriented language (ALGOL W).<br \/>\n My goal was to ensure that all use of references should be absolutely safe, with checking performed automatically by the compiler.<br \/>\n But I couldn&#8217;t resist the temptation to put in a null reference, simply because it was so easy to implement.<br \/>\n This has led to innumerable errors, vulnerabilities, and system crashes, which have probably caused a billion dollars of pain and damage in the last forty years.\n<\/p><\/blockquote>\n<p>Null\u30820\u3082\u5b58\u5728\u3057\u306a\u3044\u3001\u306a\u3044\u3068\u3044\u3046\u3053\u3068\u3067\u306f\u540c\u3058\u610f\u5473\u306a\u3093\u3060\u3051\u3069\u3001\u81ea\u5206\u306f\u3053\u3046\u7406\u89e3\u3057\u3066\u3044\u308b\u3002<\/p>\n<p>\u7bb1\u306e\u4e2d\u306e\u30ea\u30f3\u30b4\u306e\u6570\u3092\u8abf\u3079\u305f\u3044\u3068\u304d\u306b\u3001<br \/>\n\u30ea\u30f3\u30b4\u304c\u306a\u3044\u306e\u306f0\u500b<br \/>\n\u7bb1\u81ea\u4f53\u304c\u306a\u3044\u306e\u304cNull\u3002<\/p>\n<p>\u5927\u4f53\u305d\u3093\u306a\u611f\u3058\u3067\u3001\u4ed6\u306e\u4eba\u306b\u3082\u8aac\u660e\u3092\u3057\u3066\u3044\u308b\u3002<\/p>\n<p>\u3067\u3082\u3001\u3060\u3044\u305f\u3044\u3001\u306c\u308b\u307d\u3063\u3066\u3044\u3063\u305f\u3089\u3001<\/p>\n<hr \/>\n<pre>\r\n\u2227\uff3f\u2227\r\n\uff08\u3000\u00b4\u2200\uff40\uff09\uff1c \u306c\u308b\u307d\r\n<\/pre>\n<hr \/>\n<pre>\r\n\uff08\u3000\u30fb\u2200\u30fb\uff09\u3000\u3000\u3000|\u3000|\u3000\uff76\uff9e\uff6f\r\n\u3068\u3000\u3000\u3000\u3000\uff09\u3000 \u3000 |\u3000|\r\n\uff39\u3000\/\u30ce\u3000\u3000\u3000 \u4eba\r\n\/\u3000\uff09\u3000 \u3000 &lt; \u3000&gt;__\u039b\u2229\r\n\uff3f\/\u3057'\u3000\uff0f\uff0f. \uff36\uff40\u0414\u00b4\uff09\/ \u2190&gt;&gt;1\r\n\uff08\uff3f\u30d5\u5f61\u3000\u3000\u3000\u3000\u3000 \u3000\u3000\/\r\n<\/pre>\n<hr \/>\n<p>\u300c\uff76\uff9e\uff82\u300d\u3068\u6bb4\u308a\u305f\u304f\u306a\u308b<\/p>\n<blockquote class=\"twitter-tweet\" data-width=\"500\" data-dnt=\"true\">\n<p lang=\"ja\" dir=\"ltr\">1\u304b\u30899\u306e\u6570\u5b57\u3092\u767a\u898b\u3057\u305f\u30a2\u30e9\u30d3\u30a2\u4eba\u30020\u3092\u767a\u898b\u3057\u305f\u30a4\u30f3\u30c9\u4eba\u3002Null \u3092\u7523\u307f\u51fa\u3057\u305f\u30a2\u30f3\u30c8\u30cb\u30fc\u30fb\u30db\u30fc\u30a2\u6c0f\u3002<br \/>Null \u306e\u5b58\u5728\u306b\u5f8c\u6094\u3057\u3066\u3044\u308b\u30db\u30fc\u30a2\u6c0f\u3002<br \/>\u7bb1\u306e\u4e2d\u306e\u30ea\u30f3\u30b4\u306e\u6570\u3092\u8abf\u3079\u305f\u3068\u304d\u306b\u3001\u30ea\u30f3\u30b4\u304c0\u500b\u306a\u306e\u3068\u7bb1\u304c\u306a\u3044(Null)\u306f\u9055\u3046\u3053\u3068\u3060\u3051\u3069\u3055\u3002\u300c\uff76\uff9e\uff82\u300d\u3068\u6bb4\u308a\u305f\u304f\u306a\u308b\u3002<br \/> <a href=\"https:\/\/twitter.com\/hashtag\/Null?src=hash&amp;ref_src=twsrc%5Etfw\">#Null<\/a><\/p>\n<p>&mdash; \u30a2\u30ea\u30bd\u30f3 (@arisonjp) <a href=\"https:\/\/twitter.com\/arisonjp\/status\/839322266374582273?ref_src=twsrc%5Etfw\">March 8, 2017<\/a><\/p><\/blockquote>\n<p><script async src=\"https:\/\/platform.twitter.com\/widgets.js\" charset=\"utf-8\"><\/script><\/p>\n","protected":false},"excerpt":{"rendered":"<p>1\u304b\u30899\u306e\u6570\u5b57\u3092\u767a\u898b\u3057\u305f\u30a2\u30e9\u30d3\u30a2\u4eba\u3002 0\u3092\u767a\u898b\u3057\u305f\u30a4\u30f3\u30c9\u4eba\u3002 Null \u3092\u7523\u307f\u51fa\u3057\u305f\u30a2\u30f3\u30c8\u30cb\u30fc\u30fb\u30db\u30fc\u30a2\u6c0f\u3002 Null \u306e\u5b58\u5728\u306b\u5f8c\u6094\u3057\u3066\u3044\u308b\u30db\u30fc\u30a2\u6c0f\u3002 \u7bb1\u306e\u4e2d\u306e\u30ea\u30f3\u30b4\u306e\u6570\u3092\u8abf\u3079\u305f\u3068\u304d\u306b\u3001\u30ea\u30f3\u30b4\u304c0\u500b\u306a\u306e\u3068\u7bb1\u304c\u306a\u3044(Null [&hellip;]<\/p>\n","protected":false},"author":2,"featured_media":24193,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[6,4],"tags":[24,832],"class_list":["post-23493","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-programming","category-diary","tag-person","tag-quotes"],"_links":{"self":[{"href":"https:\/\/arison.jp\/blog\/wp-json\/wp\/v2\/posts\/23493","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/arison.jp\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/arison.jp\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/arison.jp\/blog\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/arison.jp\/blog\/wp-json\/wp\/v2\/comments?post=23493"}],"version-history":[{"count":2,"href":"https:\/\/arison.jp\/blog\/wp-json\/wp\/v2\/posts\/23493\/revisions"}],"predecessor-version":[{"id":29023,"href":"https:\/\/arison.jp\/blog\/wp-json\/wp\/v2\/posts\/23493\/revisions\/29023"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/arison.jp\/blog\/wp-json\/wp\/v2\/media\/24193"}],"wp:attachment":[{"href":"https:\/\/arison.jp\/blog\/wp-json\/wp\/v2\/media?parent=23493"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/arison.jp\/blog\/wp-json\/wp\/v2\/categories?post=23493"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/arison.jp\/blog\/wp-json\/wp\/v2\/tags?post=23493"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}