{"id":1960,"date":"2008-10-12T23:01:39","date_gmt":"2008-10-12T15:01:39","guid":{"rendered":"http:\/\/ihower.idv.tw\/blog\/?p=1960"},"modified":"2011-04-09T02:04:21","modified_gmt":"2011-04-08T18:04:21","slug":"object-oriented-programming-calisthenics","status":"publish","type":"post","link":"https:\/\/ihower.tw\/blog\/1960-object-oriented-programming-calisthenics","title":{"rendered":"\u7269\u4ef6\u5c0e\u5411\u7a0b\u5f0f\u7684\u4e5d\u500b\u9ad4\u64cd\u7df4\u7fd2"},"content":{"rendered":"

\u6700\u8fd1\u5728\u7ffb The ThoughtWorks Anthology<\/a>(\u77e5\u540d\u8edf\u9ad4\u9867\u554f\u516c\u53f8 Thoughtworks<\/a> \u51fa\u7684\u6587\u96c6)\uff0c\u88e1\u9762\u6709\u7bc7 Object Calisthenics \u883b\u6709\u610f\u601d\u7684\u3002<\/p>\n

\u597d\u7684\u7269\u4ef6\u5c0e\u5411\u8a2d\u8a08\u5f88\u96e3\uff0c\u6211\u5011\u90fd\u5f88\u540c\u610f\u4f55\u8b02\u597d\u7684\u8a2d\u8a08\u539f\u5247\uff1a\u9ad8\u5167\u805a\u529b(cohesion)\u3001\u4f4e\u8026\u5408(loose coupling)\u3001\u4e0d\u91cd\u8907\u7a0b\u5f0f(Don’t Repeat Yourselp)\u3001\u5c01\u88dd(encapsulation)\u3001\u53ef\u6e2c\u8a66\u6027\u3001\u6613\u95b1\u8b80\u6027\u7b49\u7b49\uff0c\u4f46\u662f\u5be6\u969b\u5beb\u7684\u6642\u5019\u537b\u4e0d\u5bb9\u6613\u5316\u8eab\u70ba\u4e00\u884c\u884c\u7684\u7a0b\u5f0f\u78bc\u3002\u9019\u7bc7\u4f5c\u8005\u5217\u4e86\u4e5d\u689d\u898f\u5247\uff0c\u4e26\u5efa\u8b70\u4f60\u7df4\u7fd2\u5beb\u500b\u5343\u884c\u7a0b\u5f0f\u56b4\u683c\u9075\u5b88\u770b\u770b\uff0c\u7528\u4ee5\u6539\u5584\u4f60\u7684OO\u5be6\u4f5c\u80fd\u529b\u3002<\/p>\n

\u521d\u6b21\u770b\u5230\u9019\u4e5d\u689d\u6642\u89ba\u5f97\u6709\u9ede\u8a87\u5f35\uff0c\u4f46\u5176\u5be6\u6fc3\u7e2e\u4e86\u4e0d\u5c11OO\u60f3\u6cd5\u5728\u88e1\u9762\uff0c\u5982\u679c\u6709\u95b1\u8b80\u904e\u91cd\u69cb\u6216\u7269\u4ef6\u5c0e\u5411\u8a2d\u8a08\u539f\u5247\u7b49\u6982\u5ff5\uff0c\u61c9\u8a72\u80fd\u5920\u806f\u60f3\u5230\u5f88\u591a\u6771\u897f\uff0c\u633a\u6709\u8da3\u7684\u3002<\/p>\n

1. \u6bcf\u500b\u51fd\u5f0f\u88e1\u9762\u53ea\u80fd\u6709\u4e00\u5c64\u7e2e\u6392\uff0c\u5982\u679c\u9700\u8981\u591a\u4e00\u5c64\uff0c\u8acb\u591a\u5beb\u4e00\u500b method \u53bb\u547c\u53eb\u3002<\/p><\/blockquote>\n

\u9019\u500b\u898f\u5247\u5176\u5be6\u5c31\u662f\u8981\u6c42\u56b4\u683c\u9075\u5b88 Compose Method<\/a>\uff1a\u5c07\u908f\u8f2f\u64cd\u4f5c\u8f49\u63db\u70ba\u7d30\u76ee\u7b49\u7d1a\u76f8\u540c\u7684\u6b65\u9a5f\uff0c\u907f\u514d\u904e\u6df1\u7684\u908f\u8f2f\u800c\u7121\u6cd5\u8fc5\u901f\u4e86\u89e3\uff0c\u76f8\u4fe1\u5927\u5bb6\u61c9\u8a72\u90fd\u6709\u770b(\u5beb)\u904eM\u578b\u7a0b\u5f0f<\/a>\u5427 :p<\/p>\n

2. \u4e0d\u8981\u4f7f\u7528\u5230 else \u9019\u500b\u95dc\u9375\u5b57\u3002<\/p><\/blockquote>\n

\u907f\u514d\u5beb\u51fa\u8907\u96dc\u7684 nested conditional \u7a0b\u5f0f\u3002\u4e0d\u8ad6\u662f”\u91cd\u69cb<\/a>“\u6216\u662f”\u91cd\u69cb\uff0d\u5411\u7bc4\u5f0f\u524d\u9032<\/a>“\u9019\u5169\u672c\u66f8\uff0c\u90fd\u6709\u5f88\u591a\u7bc7\u5e45\u82b1\u5728\u8a0e\u8ad6\u5982\u4f55\u7c21\u5316\u689d\u4ef6\u908f\u8f2f\uff0c\u4f5c\u6cd5\u5305\u62ec <\/p>\n

a. \u91cd\u69cb\u4e00\u66f8\u63d0\u5230\u7684 Replace Nested Conditional with Guard Clauses<\/a> \u65b9\u5f0f\uff0c\u76f4\u63a5\u4f7f\u7528 return \u8fd4\u56de\uff0c\u4e0d\u8981\u518d else \u4e86\u3002<\/p>\n

b. \u8acb\u611b\u7528 Ternary Operator\uff1a\u4e5f\u5c31\u662f boolean-expression ? expr1 : expr2\u3002\u5f88\u591a\u7c21\u55ae\u7684 if else \u90fd\u53ef\u4ee5\u7528 Ternary Operator \u7c21\u5316\u5230\u4e00\u884c\u4e00\u76ee\u4e86\u7136\u3002\u8209\u500b Ruby code \u4f8b\u5b50\uff1a<\/p>\n


\n if ( is_something )
\n \"foo\"
\n else
\n \"bar\"
\n end
\n<\/code>
\n\u5982\u679c\u6539\u6210\u4e09\u91cd\u64cd\u4f5c\u5b50\u5c31\u4fd0\u843d\u591a\u4e86\uff1a
\n
\n ( is_something )? \"foo\" : \"bar\"
\n<\/code><\/p>\n

\u53e6\u5916\u521d\u5fc3\u8005\u4e5f\u5e38\u5beb\u51fa\u6839\u672c\u4e0d\u9700\u8981 if else \u7684\u60c5\u6cc1\uff1a
\n
\ndef is_foobar
\n if ( a > 0 )
\n return true
\n else
\n return false
\n end
\nend
\n<\/code>
\n\u5176\u5be6\u53ea\u9700\u8981\u9019\u6a23\u5c31\u53ef\u4ee5\u4e86\uff1a
\n
\ndef is_foobar
\n ( a > 0 )
\nend
\n<\/code><\/p>\n

c. \u7b2c\u4e09\u62db\u8981\u5148\u5ff5\u9ede\u66f8\uff0c\u8acb\u5584\u7528\u7269\u4ef6\u5c0e\u5411\u7684\u591a\u578b(polymorphism)\u80fd\u529b\uff0c\u8acb\u53c3\u8003\u8a2d\u8a08\u6a21\u5f0f\u7684 Strategy pattern<\/a> \u6216\u91cd\u69cb\u7684 Replace Conditional with Polymorphism<\/a><\/p>\n

<\/p>\n

3. \u6240\u6709\u57fa\u672c\u578b\u5225\u90fd\u5305\u88dd\u6210\u7269\u4ef6 <\/p><\/blockquote>\n

\u5982\u679c\u4f60\u8981\u7528\u5230 integer \u6216 string \u7b49\u57fa\u672c\u578b\u5225\uff0c\u8acb\u591a\u7528\u4e00\u5c64\u5e36\u6709\u610f\u7fa9 Class \u5305\u88dd\u8d77\u4f86\u3002\u4f8b\u5982\u5728\u50b3\u905e “\u5e74” \u8ddf “\u6708” \u7684\u53c3\u6578\u6642\uff0c\u4e0d\u8981\u53ea\u7528 integer \u50b3\u905e\u54ea\u4e00\u5e74\u54ea\u4e00\u500b\u6708\uff0c\u800c\u662f\u7528\u500b Date \u7269\u4ef6\u5305\u88dd\u8d77\u4f86\u3002<\/p>\n

\u70ba\u4ec0\u9ebc\u5462? \u900f\u904e\u9019\u7a2e\u5c0f\u578b\u7269\u4ef6\uff0c\u6211\u5011\u53ef\u4ee5\u5beb\u51fa\u8f03\u5bb9\u6613\u7dad\u8b77\u7684\u7a0b\u5f0f\uff0c\u4e00\u770b\u5c31\u61c2\u90a3\u500b integer \u4ee3\u8868\u7684\u610f\u7fa9\u662f\u4ec0\u9ebc\u3002\u800c\u4e14\u53ea\u7528\u57fa\u672c\u578b\u5225\uff0c\u7de8\u8b6f\u5668\u4e5f\u7121\u6cd5\u5e6b\u52a9(\u5075\u6e2c)\u4f60\u5beb\u51fa\u4f60\u771f\u6b63\u60f3\u8981\u7684\u6b63\u78ba”\u8a9e\u610f”\u3002\u53e6\u5916\u4e00\u500b\u5c0f\u578b\u7269\u4ef6\u597d\u8655\u662f\u63d0\u4f9b\u4e86\u5f88\u597d\u7684\u653e method \u7684\u5730\u65b9\uff0c\u4f8b\u5982\u5728\u9019\u65b9\u9762 Ruby \u5c31\u505a\u7684\u5f88\u597d\uff0c\u56e0\u70ba\u6240\u6709\u6771\u897f\u90fd\u662f\u7269\u4ef6\uff0c\u6240\u4ee5\u751a\u81f3\u662f integer \u6216 string \u90fd\u53ef\u4ee5\u76f4\u63a5\u6709\u81ea\u5df1\u7684\u57fa\u672c\u64cd\u4f5c\uff0c\u4f8b\u5982\uff1a
\n
\n-123456.abs # 123456
\n\"FOObar\".downcase # \"foobar\"\u3002
\nTime.now.year # 2008
\n<\/code><\/p>\n

4. \u6bcf\u4e00\u884c\u53ea\u80fd\u51fa\u73fe dot \u4e00\u6b21(\u5373\u6bcf\u884c\u53ea\u80fd\u547c\u53eb\u4e00\u6b21 method)<\/p><\/blockquote>\n

\u9019\u898f\u5247\u5c0d Ruby \u53ef\u80fd\u592a\u56b4\u683c\u4e86…XD \u898f\u5247\u7684\u76ee\u7684\u662f\u8981\u6e1b\u5c11\u8026\u5408\uff0c\u907f\u514d\u7834\u58de\u5c01\u88dd\u539f\u5247\uff1a\u4f60\u53ea\u80fd\u73a9\u4f60\u7684\u73a9\u5177\uff0c\u800c\u4e0d\u662f\u73a9\u5177\u7684\u73a9\u5177\u3002\u7d30\u7bc0\u8acb\u627e The Law of Demeter (“\u53ea\u5c0d\u4f60\u7684\u670b\u53cb\u8aaa\u8a71”)\uff0c\u5f15\u7528 Qing \u9577\u8f29\u7684\u6f2b\u8ac7\u7a0b\u5f0f\u78bc\u7684\u76f8\u4f9d\u6027<\/a>\uff1a”\u5728\u9075\u5b88\u6240\u8b02\u7684Law of Demeter\u6642\uff0c\u5728\u67d0\u4e00\u7269\u4ef6\u7684\u67d0\u4e00\u51fd\u5f0f\u4e2d\u6240\u80fd\u547c\u53eb\u51fd\u5f0f\u7684\u5c0d\u8c61\u662f\u53d7\u9650\u5236\u7684\uff0c\u5b83\u53ea\u80fd\u662f\uff1a\u8a72\u7269\u4ef6\u672c\u8eab\u3001\u50b3\u5165\u8a72\u51fd\u5f0f\u7684\u5f15\u6578\u3001\u5728\u8a72\u51fd\u5f0f\u4e2d\u6240\u7522\u751f\u7684\u7269\u4ef6\u3001\u4ee5\u53ca\u8a72\u7269\u4ef6\u7684\u8cc7\u6599\u6210\u54e1\u3002\u5f88\u660e\u986f\u7684\uff0c\u4f60\u4e0d\u80fd\u5728\u6b64\u51fd\u5f0f\u4e2d\u547c\u53eb\u5176\u4ed6\u51fd\u5f0f\u6240\u56de\u50b3\u7269\u4ef6\u7684\u51fd\u5f0f\uff0c\u56e0\u70ba\u5176\u4ed6\u51fd\u5f0f\u6240\u56de\u50b3\u7684\u7269\u4ef6\uff0c\u4e26\u4e0d\u5728\u4e0a\u8ff0\u7684\u5c0d\u8c61\u4e4b\u4e2d\u3002<\/p>\n

5. \u4e0d\u8981\u7e2e\u5beb\u540d\u7a31 <\/p><\/blockquote>\n

\u6211\u8d85\u611b\u9019\u500b\u898f\u5247\uff0c\u6bcf\u6b21\u770b\u5230\u6709\u4eba\u7528\u7e2e\u5beb\u4e82\u53d6 method name \u6216 variable name\uff0c\u5c31\u89ba\u5f97\u5f88\u6293\u72c2\u3002\u5373\u4f7f\u7528 full name \u6703\u9577\u4e86\u9ede\uff0c\u4f46\u662f\u6211\u5be7\u9858\u4e00\u770b\u5c31\u61c2\u800c\u4e0d\u662f\u73a9\u731c\u8b0e(\u4f8b what’s sm? short_message? smart_phone? single_machine?)\u3002\u5373\u4f7f\u7528\u66ab\u6642\u8b8a\u6578\u6211\u4e5f\u89ba\u5f97\u61c9\u8a72\u597d\u597d\u547d\u540d\uff0c\u800c\u4e0d\u662f\u53ea\u7528\u4e00\u500b “t”\u3002\u6211\u81ea\u5df1\u5728 Textmate \u7684\u7d93\u9a57\u662f\u53ea\u8981\u6309 Esc \u5c31\u53ef\u4ee5\u81ea\u52d5\u6bd4\u5c0d\u51fa\u4f60\u8981\u7684 full name\uff0c\u5f9e\u4f86\u90fd\u4e0d\u89ba\u5f97\u6253\u5b8c\u6574\u540d\u7a31\u6703\u5f88\u8f9b\u82e6\u3002<\/p>\n

\u5982\u679c\u4f60\u771f\u7684\u89ba\u5f97\u592a\u9577\uff0c\u5c31\u61c9\u8a72\u597d\u597d\u91cd\u65b0\u601d\u8003\uff1a\u662f\u4e0d\u662f\u9019\u500b method \u653e\u932f class \u4e86? (\u653e\u5230\u5225\u7684 class \u4e4b\u4e0b\u4e5f\u8a31\u4e0d\u9700\u8981\u9019\u9ebc\u9577\u5c31\u53ef\u4ee5\u77e5\u9053\u4f5c\u7528)\u3002\u53e6\u4e00\u500b\u53d6\u540d\u5e38\u72af\u7684\u932f\u8aa4\u662f\u4e0d\u9700\u8981\u91cd\u8907 context (\u8a9e\u5883)\uff1a\u4f8b\u5982\u4e00\u500b\u53eb Order Class\uff0c\u5b83\u7684 method name \u5c31\u4e0d\u9700\u8981\u547d\u540d\u70ba ship_order (\u5373@order.ship_order)\uff0c\u53ea\u9700\u8981\u53d6\u540d ship (\u5373@order.ship)\u5c31\u597d\u4e86\u3002<\/p>\n

6. \u4fdd\u6301\u6771\u897f\u8f15\u8584<\/p><\/blockquote>\n

class \u4e0d\u8d85\u904e50\u884c\uff0c\u6bcf\u500b package \u4e0d\u8d85\u904e10\u500b\u6a94\u6848\u300250\u884c\u7684\u7a0b\u5f0f\u4e0d\u6703\u8d85\u904e\u4e00\u500b\u87a2\u5e55\uff0c\u9019\u6a23\u87a2\u5e55\u4e0d\u7528\u6372\u5c31\u53ef\u4ee5\u4e00\u6383\u800c\u904e\u3002\u9019\u500b\u6311\u6230\u5728\u65bc\u4f60\u8981\u52aa\u529b\u53bb grouping \u6709\u5171\u901a logical sense \u7684\u6771\u897f\u3002<\/p>\n

7. \u4e0d\u8981\u7528\u4efb\u4f55\u4e00\u500b\u542b\u8d85\u904e\u5169\u500b instance \u8b8a\u6578\u7684 class <\/p><\/blockquote>\n

\u9019\u5927\u6982\u662f\u6700\u96e3\u7684\u7df4\u7fd2\u4e86\uff0c\u4f5c\u8005\u8a8d\u70ba\u7576\u4e00\u500b Class \u8655\u7406\u8d85\u904e\u4e00\u500b state variable \u6642\uff0c\u5c31\u61c9\u8a72\u53e6\u5efa\u4e00\u500b\u65b0\u7684 class \u5206\u89e3\u53ca\u5305\u88dd\u8d77\u4f86\u3002\u5be6\u969b\u7684\u4f5c\u6cd5\u6211\u60f3\u53ef\u4ee5\u53c3\u8003\u91cd\u69cb\u7684 Extract Class<\/a> \u65b9\u6cd5\u3002<\/p>\n

8. \u4f7f\u7528\u7b2c\u4e00\u7d1a collections<\/p><\/blockquote>\n

\u4efb\u4f55\u5305\u542b collection \u7684\u985e\u5225\u5c31\u4e0d\u61c9\u8a72\u518d\u542b\u6709\u5225\u7684\u8b8a\u6578\uff0c\u4e5f\u5c31\u662f\u4f60\u61c9\u8a72\u628a collection \u7576\u505a\u4e00\u500b\u5f88\u57fa\u672c\u7684\u985e\u5225\u4f86\u4f7f\u7528\u3002<\/p>\n

9. \u4e0d\u8981\u4f7f\u7528\u4efb\u4f55 getters\/setters\/properties<\/p><\/blockquote>\n

\u76ee\u6a19\u662f\u8981\u7df4\u7fd2 “Tell, don’t ask” \u539f\u5247\uff0c\u4f60\u61c9\u8a72\u76e1\u91cf\u544a\u8a34\u7269\u4ef6\u4f60\u60f3\u8981\u4ec0\u9ebc(tell)\uff0c\u800c\u4e0d\u662f\u53bb\u554f(ask)\u7269\u4ef6\u7684\u72c0\u614b\uff0c\u7136\u5f8c\u505a\u6c7a\u5b9a\uff0c\u518d\u544a\u8a34\u7269\u4ef6\u505a\u4ec0\u9ebc\u3002\u66f4\u8a73\u7d30\u53ef\u4ee5\u770b\u770b The Pragmatic Bookshelf \u7684 Tell, Don’t Ask<\/a> \u4e00\u6587 (\u9019\u7bc7\u4e5f\u6709\u63d0\u5230Law of Demeter)\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"

\u6700\u8fd1\u5728\u7ffb The ThoughtWorks Anthology(\u77e5\u540d\u8edf\u9ad4\u9867\u554f\u516c\u53f8 Thoughtworks \u51fa … <\/p>\n

\u95b1\u8b80\u5168\u6587\u3008\u7269\u4ef6\u5c0e\u5411\u7a0b\u5f0f\u7684\u4e5d\u500b\u9ad4\u64cd\u7df4\u7fd2\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":[51,5,31],"tags":[],"class_list":["post-1960","post","type-post","status-publish","format-standard","hentry","category-agile","category-programming","category-ruby","entry"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_shortlink":"https:\/\/wp.me\/p1q6tG-vC","jetpack_sharing_enabled":true,"jetpack_likes_enabled":true,"_links":{"self":[{"href":"https:\/\/ihower.tw\/blog\/wp-json\/wp\/v2\/posts\/1960","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=1960"}],"version-history":[{"count":39,"href":"https:\/\/ihower.tw\/blog\/wp-json\/wp\/v2\/posts\/1960\/revisions"}],"predecessor-version":[{"id":5556,"href":"https:\/\/ihower.tw\/blog\/wp-json\/wp\/v2\/posts\/1960\/revisions\/5556"}],"wp:attachment":[{"href":"https:\/\/ihower.tw\/blog\/wp-json\/wp\/v2\/media?parent=1960"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ihower.tw\/blog\/wp-json\/wp\/v2\/categories?post=1960"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ihower.tw\/blog\/wp-json\/wp\/v2\/tags?post=1960"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}