{"id":1697,"date":"2008-02-09T06:49:26","date_gmt":"2008-02-08T22:49:26","guid":{"rendered":"http:\/\/ihower.idv.tw\/blog\/archives\/1697"},"modified":"2011-04-09T02:16:48","modified_gmt":"2011-04-08T18:16:48","slug":"ruby-singleton-class","status":"publish","type":"post","link":"https:\/\/ihower.tw\/blog\/1697-ruby-singleton-class","title":{"rendered":"\u4e00\u4e9b Ruby Dynamic Features \u8a18\u4e8b (2) singleton class"},"content":{"rendered":"<p>\u5728Ruby\u4e2d\uff0csingleton method\u6307\u7684\u662f\u53ea\u6709\u8a72\u7269\u4ef6\u624d\u6709\u7684\u65b9\u6cd5\uff0c\u800c\u52a0\u5728 Class object \u4e0a\u7684 singleton method \u4e5f\u5c31\u8b8a\u6210\u4e86 class method\u3002<\/p>\n<p><!--more--><\/p>\n<p>\u5047\u8a2d\u76ee\u524d\u6709\u4ee5\u4e0b\u7684\u7a0b\u5f0f\u78bc:<\/p>\n<pre>\r\n class Dragon\r\n end\r\n dran = Dragon.new\r\n<\/pre>\n<h2>\u6211\u60f3\u5b9a\u7fa9\u7269\u4ef6\u65b9\u6cd5 dran.foo<\/h2>\n<pre>\r\n#\u6cd5\u4e00\r\nclass Dragon\r\n    def n\r\n        puts \"nnn\"\r\n    end\r\nend\r\n#\u6cd5\u4e8c\r\nDragon.class_eval do\r\n    def foo\r\n        puts \"bar\"\r\n    end\r\nend\r\n<\/pre>\n<h2>\u6211\u60f3\u5b9a\u7fa9\u53ea\u6709\u9019\u500b\u7269\u4ef6\u624d\u6709\u7684\u65b9\u6cd5 dran.foo (\u53eb\u505a singleton method)<\/h2>\n<pre>\r\n#\u6cd5\u4e00\r\nclass &lt;&lt; dran \r\n    def foo\r\n        puts \"bar\"\r\n    end\r\nend\r\ndrag.foo\r\n\r\n#\u6cd5\u4e8c\r\ndrgn.instance_eval do\r\n    def foo\r\n        puts \"bar\"\r\n    end\r\nend\r\n\r\n#\u6cd5\u4e09\r\ndef dran.foo\r\n    puts \"bar\"\r\nend\r\n<\/pre>\n<h2>\u6211\u60f3\u5b9a\u7fa9\u985e\u5225\u65b9\u6cd5 Dragon.foo (class methods) <\/h2>\n<pre>\r\n#\u6cd5\u4e00\r\nclass &lt;&lt; Dragon\r\n    def foo\r\n        puts \"bar\"\r\n    end\r\nend\r\n\r\n#\u6cd5\u4e8c\r\nclass Dragon\r\n    def self.foo\r\n        puts \"bar\"\r\n    end\r\nend\r\n\r\n#\u6cd5\u4e09\r\nclass Dragon\r\n    class &lt;&lt; self\r\n        def foo\r\n            puts \"bar\"\r\n        end\r\n     end\r\nend\r\n\r\n#\u6cd5\u56db\r\nDragon.instance_eval\r\n    def foo\r\n     puts \"bar\"\r\n    end\r\nend\r\n\r\n#\u6cd5\u4e94\r\n\r\nDragon.class_eval do # \u9019\u88e1\u6539\u7528 instance_eval \u4e5f\u53ef\u4ee5\u8036(why?)\r\n  def self.foo\r\n    puts \"bar\"\r\n  end\r\nend\r\n\r\n<\/pre>\n","protected":false},"excerpt":{"rendered":"<p>\u5728Ruby\u4e2d\uff0csingleton method\u6307\u7684\u662f\u53ea\u6709\u8a72\u7269\u4ef6\u624d\u6709\u7684\u65b9\u6cd5\uff0c\u800c\u52a0\u5728 Class object \u4e0a &hellip; <\/p>\n<p class=\"link-more\"><a href=\"https:\/\/ihower.tw\/blog\/1697-ruby-singleton-class\" class=\"more-link\">\u95b1\u8b80\u5168\u6587<span class=\"screen-reader-text\">\u3008\u4e00\u4e9b Ruby Dynamic Features \u8a18\u4e8b (2) singleton class\u3009<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[5,31],"tags":[],"class_list":["post-1697","post","type-post","status-publish","format-standard","hentry","category-programming","category-ruby","entry"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_shortlink":"https:\/\/wp.me\/p1q6tG-rn","jetpack_sharing_enabled":true,"jetpack_likes_enabled":true,"_links":{"self":[{"href":"https:\/\/ihower.tw\/blog\/wp-json\/wp\/v2\/posts\/1697","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ihower.tw\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ihower.tw\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ihower.tw\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/ihower.tw\/blog\/wp-json\/wp\/v2\/comments?post=1697"}],"version-history":[{"count":2,"href":"https:\/\/ihower.tw\/blog\/wp-json\/wp\/v2\/posts\/1697\/revisions"}],"predecessor-version":[{"id":5586,"href":"https:\/\/ihower.tw\/blog\/wp-json\/wp\/v2\/posts\/1697\/revisions\/5586"}],"wp:attachment":[{"href":"https:\/\/ihower.tw\/blog\/wp-json\/wp\/v2\/media?parent=1697"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ihower.tw\/blog\/wp-json\/wp\/v2\/categories?post=1697"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ihower.tw\/blog\/wp-json\/wp\/v2\/tags?post=1697"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}