{"id":1898,"date":"2009-01-03T00:25:49","date_gmt":"2009-01-02T16:25:49","guid":{"rendered":"http:\/\/ihower.idv.tw\/blog\/?p=1898"},"modified":"2015-09-05T10:46:16","modified_gmt":"2015-09-05T02:46:16","slug":"practices-of-an-agile-developer-4-programming","status":"publish","type":"post","link":"https:\/\/ihower.tw\/blog\/1898-practices-of-an-agile-developer-4-programming","title":{"rendered":"\u5be6\u6230\u654f\u6377\u958b\u767c Practices of an Agile Developer (4) \u7a0b\u5f0f\u7bc7"},"content":{"rendered":"<p>\u8d81\u8457\u65b0\u5e74\u9023\u7e8c\u5047\u671f\uff0c\u7d42\u65bc\u628a\u9019\u4e00\u7ae0\u5ff5\u5b8c\u4e86\uff1a\u96a8\u8457\u958b\u767c\u7684\u9032\u5c55\uff0c\u7a0b\u5f0f\u9010\u6f38\u8b8a\u5f97\u602a\u7378\u3002\u9019\u7ae0\u8ac7\u5e7e\u500b\u91cd\u9ede\u5e6b\u52a9\u4f60\u8b93\u7a0b\u5f0f\u5bb9\u6613\u4e86\u89e3\u3001\u64f4\u5145\u53ca\u7dad\u8b77\u3002<\/p>\n<h3>Program Intently and Expressively (\u5beb\u6e05\u695a\u4e86\u89e3\u7684\u7a0b\u5f0f)<\/h3>\n<p>\u53b2\u5bb3\u7684\u7a0b\u5f0f\u662f\u6c92\u6709\u4eba\u53ef\u4ee5\u770b\u61c2\u7684\u7a0b\u5f0f\uff1f\u7a0b\u5f0f\u7684\u53ef\u95b1\u8b80\u6027\u6bd4\u5beb\u5f97\u65b9\u4fbf\u9084\u91cd\u8981\uff0c\u5beb\u53ea\u6703\u5beb\u4e00\u904d\uff0c\u770b\u537b\u6703\u770b\u5f88\u591a\u6b21\u3002\u5f88\u591a\u6642\u5019\u6703\u6709\u6a5f\u6703\u8981\u4fee Bugs \u6216\u662f\u65b0\u589e\u529f\u80fd\uff0c\u9019\u6642\u641e\u61c2\u672c\u4f86\u7684\u7a0b\u5f0f\u5e38\u5e38\u662f\u4e00\u958b\u59cb\u6700\u56f0\u96e3\u7684\u5730\u65b9\uff0c\u5982\u679c\u4e00\u958b\u59cb\u5beb\u7684\u4eba\u5c31\u4ee5\u53ef\u8b80\u6027\u70ba\u91cd\u8981\u76ee\u6a19\uff0c\u90a3\u4f60\u5c31\u6703\u8f15\u9b06\u7684\u591a\u3002<\/p>\n<p>\u8209\u500b\u6211\u81ea\u5df1\u5e38\u898b\u7684\u4f8b\u5b50\u5c31\u662f Magic Number\uff0c\u5f88\u591a\u4eba\u559c\u6b61\u662f\u4e00\u500b\u6578\u5b57\u4f86\u4ee3\u8868 Type code\u3002\u4f8b\u5982 1 \u4ee3\u8868 foo\u30012 \u4ee3\u8868 bar\u30013\u4ee3\u8868&#8230;etc\uff0c\u7136\u5f8c\u7a0b\u5f0f\u88e1\u9762\u5c31\u76f4\u63a5\u5beb 1, 2, 3\u3002\u65b9\u4fbf\u662f\u65b9\u4fbf\uff0c\u4f46\u662f\u6c92\u591a\u4e45\u5c31\u6703\u5fd8\u8a18\u9019\u500b 1,2,3 \u5404\u4ee3\u8868\u4ec0\u9ebc\u610f\u7fa9\u3002\u6700\u7c21\u55ae\u7684\u89e3\u6c7a\u624b\u6cd5\u5c31\u662f\u8acb\u6539\u7528\u5b57\u4e32 constant \u8655\u7406\uff0c\u6216\u8005\u662f\u7528 class \u4f86\u8868\u793a type\u3002<\/p>\n<p>\u900f\u904e\u7a0b\u5f0f\u8a9e\u8a00\u672c\u8eab\u7684\u7279\u8272\u53ef\u4ee5\u5beb\u51fa\u66f4\u6709\u8868\u9054\u529b\u7684\u7a0b\u5f0f\uff0c\u51fd\u6578\u540d\u7a31\u61c9\u8a72\u50b3\u9054\u51fa\u610f\u5716\u3001\u53c3\u6578\u540d\u7a31\u61c9\u8a72\u8868\u9054\u51fa\u4ed6\u5011\u7684\u7528\u9014\uff0c\u5beb\u51fa\u597d\u95b1\u8b80\u7684\u7a0b\u5f0f\u6211\u5011\u53ef\u4ee5\u907f\u514d\u5f88\u591a\u4e0d\u5fc5\u8981\u7684\u8a3b\u89e3\u8ddf\u8aaa\u660e\u6587\u4ef6\u3002\u4e00\u4e9b\u4f60\u89ba\u5f97\u660e\u986f\u7c21\u55ae\u7684\u5730\u65b9\uff0c\u4e0d\u4e00\u5b9a\u5c0d\u5225\u4eba\u4e5f\u662f\u5982\u6b64\u660e\u986f\uff0c\u751a\u81f3\u662f\u5e7e\u500b\u6708\u5f8c\u7684\u4f60\u81ea\u5df1\u3002\u8acb\u60f3\u60f3\u770b\u5e7e\u500b\u6708\u5f8c\u81ea\u5df1\u4f86\u770b\u9084\u6703\u770b\u5f97\u61c2\u55ce?<\/p>\n<h3>Communicate in Code (\u5beb\u51fa\u53ef\u4ee5\u95b1\u8b80\u7684\u7a0b\u5f0f)<\/h3>\n<p>\u6211\u5011\u90fd\u8a0e\u53ad\u5beb\u6587\u4ef6\u7684\u4e00\u5927\u7406\u7531\u662f\uff1a\u6240\u8b02\u7684\u6587\u4ef6\u8ddf\u7a0b\u5f0f\u78bc\u5e38\u662f\u5206\u958b\u7684\u5169\u78bc\u5b50\u4e8b\uff0c\u56e0\u6b64\u5f88\u96e3\u8b93\u6587\u4ef6\u8ddf\u7684\u4e0a\u7a0b\u5f0f\u7684\u66f4\u65b0\uff0c\u6700\u7d42\u8b8a\u5f97\u96e3\u4ee5\u7dad\u8b77\u3002\u56e0\u6b64\u6700\u597d\u7684\u5beb\u6587\u4ef6\u65b9\u5f0f\uff0c\u5c31\u662f\u900f\u904e\u7a0b\u5f0f\u672c\u8eab\u548c\u7a0b\u5f0f\u4e2d\u7684\u8a3b\u89e3\u3002<\/p>\n<p>\u8a3b\u89e3\u662f\u7528\u4f86\u5beb\u76ee\u7684\u3001\u9650\u5236\u689d\u4ef6\u8ddf\u9810\u671f\u7d50\u679c\u7b49\uff0c\u800c\u4e0d\u662f\u5beb\u51fa\u4ee5\u4e0b\u9019\u4e9b\u7a0b\u5f0f\u4e00\u884c\u884c\u6703\u505a\u4e9b\u4ec0\u9ebc(\u8acb\u4e0d\u8981\u62ff\u8a3b\u89e3\u518d\u5beb\u4e00\u6b21\u7a0b\u5f0f\u78bc\u5728\u5beb\u7684\u4e8b\u60c5)\u3002\u4e00\u500b\u7c21\u55ae\u7684\u5224\u65b7\u65b9\u5f0f\u662f\uff1a\u5beb\u5728\u51fd\u5f0f &#8220;\u88e1\u9762&#8221; \u7684\u8a3b\u89e3\u591a\u534a\u662f\u4e0d\u9700\u8981\u7684 (\u5c24\u5176\u662f\u8a3b\u89e3\u5beb what? \u800c\u4e0d\u662f\u8a3b\u89e3 why?)\u3002\u5728\u91cd\u69cb\u4e00\u66f8\u66f4\u76f4\u8a00\u56de\u7b54\u54ea\u88e1\u9700\u8981\u91cd\u69cb\uff1f\u90a3\u5c31\u662f\u6709\u8a3b\u89e3\u7684\u5730\u65b9\uff1a\u5982\u679c\u7a0b\u5f0f\u78bc\u524d\u65b9\u6709\u4e00\u884c\u8a3b\u91cb\uff0c\u5c31\u662f\u5728\u63d0\u9192\u4f60\uff0c\u53ef\u4ee5\u5c07\u9019\u6bb5\u7a0b\u5f0f\u78bc\u66ff\u63db\u6210\u4e00\u500b\u51fd\u5f0f\uff0c\u800c\u4e14\u53ef\u4ee5\u5728\u8a3b\u91cb\u7684\u57fa\u790e\u4e0a\u7d66\u9019\u500b\u51fd\u5f0f\u547d\u540d\u3002<\/p>\n<p>\u4f60\u8981\u505a\u7684\u4e8b\u60c5\u61c9\u8a72\u662f\u8b93 source code \u672c\u8eab\u5bb9\u6613\u4e86\u89e3\uff0c\u800c\u4e0d\u662f\u900f\u904e\u8a3b\u89e3\u3002\u900f\u904e\u6b63\u78ba\u7684\u8b8a\u6578\u547d\u540d\u3001\u597d\u7684\u7a7a\u767d\u9593\u9694\u3001\u908f\u8f2f\u5206\u96e2\u6e05\u695a\u7684\u57f7\u884c\u8def\u5f91\u7b49\u624b\u6cd5\uff0c\u6211\u5011\u5f88\u5c11\u9700\u8981\u5728\u51fd\u5f0f\u88e1\u9762\u8a3b\u660e\u9019\u4e9b\u7a0b\u5f0f\u5728\u505a\u4ec0\u9ebc\uff0c\u6211\u81ea\u5df1\u7684\u7d93\u9a57\u9664\u975e\u662f\u6709\u53c3\u8003\u5916\u90e8\u7684\u7a0b\u5f0f\u78bc\u6216\u8907\u96dc\u6f14\u7b97\u6cd5\uff0c\u6211\u6703\u591a\u8a3b\u660e\u53c3\u8003\u4f86\u6e90(\u7db2\u5740)\u3002\u5426\u5247\u6c92\u6709\u5fc5\u8981\u7684\u8a3b\u89e3\u5c0d\u6211\u4f86\u8aaa\u5c31\u50cf\u566a\u97f3\u4e00\u6a23\uff0c\u59a8\u7919\u95b1\u8b80\u3002<\/p>\n<p>\u8b8a\u6578\u8ddf\u51fd\u5f0f\u7684\u547d\u540d\u662f\u4ef6\u975e\u5e38\u91cd\u8981\u7684\u4e8b\u60c5\uff0c\u6709\u610f\u7fa9\u7684\u547d\u540d\u53ef\u4ee5\u50b3\u9054\u51fa\u7a0b\u5f0f\u600e\u9ebc\u9032\u884c\uff0c\u6211\u8209\u500b Rails \u4f8b\u5b50\uff1a<\/p>\n<p><code><\/p>\n<pre>\np = Post.find(param[:id])\nif p\n   p.destroy\nelse\n   p = Post.new( param[:post] )\n   p.save\nend\n<\/pre>\n<p><\/code><br \/>\n\u53ef\u4ee5\u6539\u5beb\u6210\u4ee5\u4e0b\u9019\u6a23\u5177\u6709\u6e05\u695a\u610f\u542b\uff1a<br \/>\n<code><\/p>\n<pre>\nexisted_post = Post.find(param[:id])\nif existed_post\n  existed_post.destroy\nelse\n  new_post = Post.new( param[:post] )\n  new_post.save\nend\n<\/pre>\n<p><\/code><\/p>\n<p>\u6709\u4e00\u7a2e Job security \u7684\u65b9\u5f0f\u5c31\u662f\u628a\u7a0b\u5f0f\u4e2d\u6240\u6709\u7684\u8b8a\u6578\u540d\u7a31\u90fd\u4ee3\u63db\u6210\u4e82\u78bc\uff0c\u4fdd\u8b49\u62ff\u5230\u7684\u4eba\u8d85\u7d1a\u96e3\u770b\u5f97\u61c2\u3002\u9019\u5c31\u662f\u70ba\u4ec0\u9ebc\u624b\u5de5\u6253\u9020\u7684\u7a0b\u5f0f\u78bc\u6709\u5176\u4e0d\u53ef\u53d6\u4ee3\u7684\u91cd\u8981\u6027\uff0c\u53ea\u8981\u62ff\u5230\u6574\u5408\u578b IDE \u50cf\u662f Dreamweaver \u7522\u751f\u51fa\u4f86\u7684 HTML\/CSS code \u90fd\u5f88\u60f3\u6bba\u4eba\uff0c\u56e0\u70ba\u88e1\u9762\u7684\u8b8a\u6578\u90fd\u662f\u7de8\u865f\u7522\u751f\u51fa\u4f86\u7684\uff0c\u6839\u672c\u6c92\u8fa6\u6cd5\u95b1\u8b80\u53ca\u64f4\u5145\u3002<\/p>\n<p>\u53e6\u5916\u5c31\u662f\u5927\u5bb6\u5f88\u559c\u6b61\u7528\u7e2e\u5beb\uff0c\u9019\u5728\u6211\u4e4b\u524d\u5beb\u7684\u6587\u7ae0 <a href=\"\/blog\/archives\/1960\">\u7269\u4ef6\u5c0e\u5411\u7a0b\u5f0f\u7684\u4e5d\u500b\u9ad4\u64cd\u7df4\u7fd2 <\/a>\u4e5f\u6709\u63d0\u5230\uff0c\u9019\u4e9b\u53ea\u6709\u4e00\u500b\u5b57\u6bcd\u7684\u66ab\u6642\u8b8a\u6578\u4e26\u6c92\u6709\u8fa6\u6cd5\u50b3\u9054\u51fa\u4efb\u4f55\u53ef\u4ee5\u5e6b\u52a9\u4e86\u89e3\u7684\u8cc7\u8a0a\u3002<\/p>\n<p>Class, module, method \u524d\u9762\u662f\u500b\u5beb\u8a3b\u89e3\u7684\u597d\u5730\u65b9\uff0c\u800c\u4e14\u6bcf\u500b\u8a9e\u8a00\u90fd\u6709\u5de5\u5177(\u4f8b\u5982 RDoc, Javadoc&#8230; \u7b49)\u53ef\u4ee5\u5e6b\u5fd9\u5f9e\u7a0b\u5f0f\u78bc\u4e2d\u6574\u7406\u51fa\u597d\u770b\u7684\u7d14\u6587\u4ef6\uff0c\u9019\u4e9b\u8aaa\u660e\u901a\u5e38\u6709\uff1a<\/p>\n<ul>\n<li>Purpose \u76ee\u7684<\/li>\n<li>Requirements(pre-conditions) \u9810\u671f\u7684\u8f38\u5165\u662f\u4ec0\u9ebc<\/li>\n<li>Promises(post-conditions) \u4ec0\u9ebc\u6a23\u7684\u8f38\u5165\uff0c\u6703\u6709\u4ec0\u9ebc\u6a23\u7684\u9810\u671f\u8f38\u51fa<\/li>\n<li>Exceptions: \u6709\u54ea\u4e9b\u4f8b\u5916(exceptions)\u60c5\u6cc1<\/li>\n<\/ul>\n<p>\u9019\u4e9b\u8aaa\u660e\u53ef\u4ee5\u5e6b\u52a9\u6211\u5011\u7531\u5927\u5c40\u89c0\u4e86\u89e3\u7a0b\u5f0f\u662f\u600e\u9ebc\u904b\u4f5c\u7684\uff0c\u800c\u4e0d\u9700\u8981\u4ed4\u7d30\u770b\u5176\u4e2d\u6bcf\u500b method\u3002<br \/>\n<!--more--><\/p>\n<h3>Actively Evaluate Trade-Offs (\u7a4d\u6975\u5730\u8a55\u4f30 Trade-offs)<\/h3>\n<p>\u6548\u80fd\u5f88\u91cd\u8981\uff0c\u4f46\u662f\u5982\u679c Performance \u5df2\u7d93\u9054\u5230\u5408\u7406\u8981\u6c42\u4e86\uff0c\u8acb\u4e5f\u8003\u616e\u5be6\u505a\u65b9\u4e0d\u65b9\u4fbf\u3001\u82b1\u8cbb\u7684\u6210\u672c\u8ddf\u6642\u9593\uff0c\u800c\u4e0d\u662f\u53ea\u60f3&#8221;\u66f4\u5feb\u4e00\u9ede&#8221;\u4e86\u3002\u5929\u5e95\u4e0b\u6c92\u6709\u5b8c\u7f8e\u7684\u89e3\u6c7a\u65b9\u6848\uff0c\u4e00\u5207\u90fd\u6709 trade-off\uff0c\u5982\u679c\u6c92\u8fa6\u6cd5\u505a\u6c7a\u5b9a\uff0c\u8acb\u53bb\u554f\u91d1\u4e3b\u3002<\/p>\n<p>\u9019\u88e1\u7684\u540d\u8a00\u8b66\u53e5\u9084\u662f\u90a3\u53e5\u8001\u8a71\uff1aPremature optimization is the root of all evil.<\/p>\n<h3>Code in Increments (\u905e\u589e\u5f0f\u5beb\u7a0b\u5f0f)<\/h3>\n<p>\u5beb\u7a0b\u5f0f\u7684 edit\/build\/test \u9031\u671f\u8981\u77ed\uff0c\u52a0\u4e0a\u4e0d\u65b7\u7684\u91cd\u69cb\u6539\u9032\uff0c\u624d\u6703\u5beb\u51fa\u5bb9\u6613\u95b1\u8b80\u3001\u5bb9\u6613\u6e2c\u8a66\u7684\u5c0f\u51fd\u5f0f\u548c\u9ad8\u5167\u805a\u529b\u7684\u985e\u5225\uff0c\u800c\u4e0d\u662f\u4e00\u5927\u6cb1\u8907\u96dc\u7121\u6cd5\u638c\u63e1\u7684\u7a0b\u5f0f\u3002<\/p>\n<h3>Keep It Simple (\u4fdd\u6301\u7cbe\u5de7)<\/h3>\n<p>\u7576\u5b78\u5230\u65b0\u7684 Patterns\u3001Principles \u6216\u6280\u8853\u6642\uff0c\u8acb\u62b5\u64cb\u4f4f\u904e\u5ea6\u8a2d\u8a08\u548c\u904e\u5ea6\u8907\u96dc\u5316\u7a0b\u5f0f\u78bc\u7684\u58d3\u529b\u3002\u4f8b\u5982\u5728\u5b78 GoF \u66f8\u7684\u6642\u5019\uff0c\u5f88\u591a\u4eba\u5e38\u6703\u904e\u5ea6\u5957\u7528\u5176\u4e2d\u7684\u6a23\u5f0f\uff0c\u800c\u9020\u6210\u904e\u5ea6\u8a2d\u8a08\u3002\u76e1\u91cf\u767c\u5c55\u51fa\u6700\u7c21\u660e\u7684\u89e3\u6c7a\u65b9\u6848\uff0c\u4efb\u4f55\u7b28\u86cb\u90fd\u6709\u8fa6\u6cd5\u628a\u7a0b\u5f0f\u5beb\u7684\u66f4\u5927\u66f4\u8907\u96dc\u66f4\u66b4\u529b\u3002<\/p>\n<p>\u5c0d Simplicity \u6982\u5ff5\u6709\u8208\u8da3\u7684\u670b\u53cb\uff0c\u6211\u63a8\u85a6\u53ef\u4ee5\u53bb\u7ffb\u7ffb\u9019\u672c\u66f8<br \/>\n<a href=\"http:\/\/www.books.com.tw\/exep\/assp.php\/ihower\/exep\/prod\/booksfile.php?item=0010358782\">\u7c21\u55ae\u7684\u6cd5\u5247<\/a>\u3002<\/p>\n<h3>Write Cohesive Code (\u9ad8\u5167\u805a\u529b\u7684\u7a0b\u5f0f)<\/h3>\n<p>\u5167\u805a\u529b\u4e00\u7a2e\u8a55\u4f30\u5143\u4ef6\u88e1\u9762\u7684\u529f\u80fd\u76f8\u95dc\u5ea6\u9ad8\u4f4e\u7684\u6982\u5ff5\u3002\u5982\u4f55\u7d44\u7e54\u5143\u4ef6 (\u4f8b\u5982\u8981\u5beb\u4e00\u6bb5\u65b0\u7a0b\u5f0f\uff0c\u7b2c\u4e00\u4ef6\u4e8b\u5c31\u662f\u6c7a\u5b9a\u8981\u628a\u9019\u6bb5\u7a0b\u5f0f\u653e\u5728\u54ea\u88e1) \u6703\u9020\u6210\u751f\u7522\u529b\u548c\u7dad\u8b77\u4e0a\u7684\u91cd\u5927\u7684\u5f71\u97ff\u3002\u4e00\u500b\u5143\u4ef6(component)\u4e2d\u7684\u985e\u5225\u61c9\u8a72\u662f\u8981\u9ad8\u5ea6\u76f8\u95dc\u7684\u3001\u4e00\u500b\u985e\u5225\u4e2d\u7684\u51fd\u5f0f\u61c9\u8a72\u662f\u8981\u9ad8\u5ea6\u76f8\u95dc\u7684\u3002<\/p>\n<p>\u70ba\u4ec0\u9ebc\u5167\u805a\u529b\u91cd\u8981\uff1f\u56e0\u70ba\u6211\u5011\u90fd\u5e0c\u671b\u8edf\u9ad4\u80fd\u5920\u5bb9\u6613\u88ab\u4fee\u6539\uff0c\u4e00\u65e6\u9700\u8981\u4fee\u6539\uff0c\u6211\u5011\u5e0c\u671b\u80fd\u5920\u8df3\u5230\u7a0b\u5f0f\u4e2d\u7684\u67d0\u4e00\u6bb5\uff0c\u7136\u5f8c\u53ea\u8981\u5728\u90a3\u88e1\u6539\u597d\u5c31\u53ef\u4ee5\u4e86\u3002\u4e00\u500b\u5167\u805a\u529b\u4e0d\u5920\u7684\u8edf\u9ad4\uff0c\u7576\u4f60\u8981\u4fee\u6539\u7a0b\u5f0f\u7684\u6642\u5019\u5c31\u5f97\u591a\u7ffb\u5f88\u591a\u5730\u65b9\uff0c\u6bcf\u9047\u5230\u67d0\u7a2e\u8b8a\u5316\uff0c\u800c\u8981\u4fee\u6539\u7684\u7a0b\u5f0f\u78bc\u6563\u4f48\u56db\u8655\uff0c\u4e0d\u4f46\u96e3\u4ee5\u627e\u5230\uff0c\u4e5f\u5f88\u5bb9\u6613\u5fd8\u8a18(\u5728\u91cd\u69cb\u4e00\u66f8\u7684\uff0c\u6307\u9019\u7a2e\u58de\u5473\u9053\u53eb\u505a\u6563\u5f48\u5f0f\u4fee\u6539)\u3002<\/p>\n<p>\u53e6\u4e00\u500b\u4f4e\u5167\u805a\u529b\u7684\u5f8c\u679c\u662f\u767c\u6563\u5f0f\u8b8a\u5316\uff1a\u6bd4\u5982\u8aaa\u4e00\u500b\u985e\u5225\u88e1\u9762\u6709\u4e94\u500b\u529f\u80fd\u5168\u7570\u7684\u51fd\u5f0f\uff0c\u90a3\u9ebc\u7576\u9019\u4e94\u500b\u51fd\u5f0f\u4efb\u4e00\u500b\u767c\u751f\u9700\u6c42\u6642\uff0c\u6211\u5011\u5c31\u5fc5\u9808\u8981\u53bb\u4fee\u6539\u9019\u500b\u985e\u5225\uff0c\u800c\u4e00\u500b\u983b\u65bc\u4fee\u6539\u7684\u4e0d\u7a69\u5b9a\u985e\u5225\u6703\u9020\u6210\u7dad\u8b77\u4e0a\u7684\u4e0d\u6613\u3002\u6709\u500b\u7269\u4ef6\u5c0e\u5411\u7684\u539f\u5247\u5c31\u662f\u5728\u8b1b\u9019\u4ef6\u4e8b\uff1aSingle Responsibility Principle (SRP) \u985e\u5225\u8b8a\u66f4\u7684\u539f\u56e0\u61c9\u50c5\u53ea\u6709\u4e00\u7a2e \uff0c\u63db\u53e5\u8a71\u8aaa\u5c31\u662f\u4e00\u500b\u7269\u4ef6\u53ea\u56e0\u4e00\u7a2e\u8b8a\u5316\u800c\u9700\u8981\u4fee\u6539\u3002<\/p>\n<p>\u4e00\u500b\u5167\u805a\u529b\u5f88\u7cdf\u7684\u4f8b\u5b50\u5c31\u662f\u50b3\u7d71\u7684 PHP\/ASP \u7a0b\u5f0f\u4e86\uff0c\u6bcf\u4e00\u9801\u90fd\u6709 HTML, JavaScript, embedded SQL, business login \u5168\u90e8\u6df7\u5728\u4e00\u8d77\uff0c\u7576\u8981\u8b8a\u66f4 Table schema \u6642\uff0c\u5c31\u5fc5\u9808\u6bcf\u500b\u9801\u9762\u90fd\u8981\u4fee\u6539\uff0c\u771f\u662f\u707d\u96e3\u4e00\u5834\u3002\u89e3\u6c7a\u65b9\u6cd5\u5c31\u662f\u5f15\u9032 MVC \u7684\u67b6\u69cb\uff0c\u5206\u96e2\u51fa presentation logic \u548c business logic\u3002<\/p>\n<p>\u9019\u7bc0\u7684\u5fe0\u544a\u662f\uff1a\u4e00\u500b\u985e\u5225\u61c9\u8a72\u8981\u5920\u805a\u7126(focused)\u3001\u4e00\u500b\u5143\u4ef6(component)\u61c9\u8a72\u8981\u5920\u5c0f\uff0c\u907f\u514d\u5beb\u51fa\u592a\u5927\u7684\u985e\u5225\u6216\u5143\u4ef6\u3001\u907f\u514d\u5beb\u51fa\u529f\u80fd\u6df7\u96dc\u7684\u901a\u5403\u985e\u5225\u3002<\/p>\n<h3>Tell, Don&#8217;t Ask<\/h3>\n<blockquote><p>\n&#8220;Procedural code gets information and then makes decisions. Object-oriented code tells objects to do things&#8221; by Alec Sharp.\n<\/p><\/blockquote>\n<p>\u4f60\u61c9\u8a72\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\u518d\u544a\u8a34\u7269\u4ef6\u8981\u505a\u4ec0\u9ebc\u3002\u6839\u64da\u88ab\u547c\u53eb\u8005\u7684\u72c0\u614b\u4f86\u505a\u6c7a\u5b9a\u7684\u908f\u8f2f\u61c9\u8a72\u662f\u88ab\u547c\u53eb\u8005\u7684\u8cac\u4efb\u3002<\/p>\n<p>\u4e00\u500b\u8ddf Tell, Don&#8217;t Ask \u76f8\u95dc\u7684\u624b\u6cd5\u662f\u628a\u6240\u6709\u4f60\u7684\u51fd\u5f0f\u90fd\u53ea\u5206\u6210 Command \u548c Query \u5169\u7a2e\uff0c\u524d\u8005\u6703\u6539\u8b8a\u67d0\u7a2e\u72c0\u614b(\u70ba\u4e86\u65b9\u4fbf\u4e5f\u8a31\u6703\u56de\u50b3\u4e00\u4e9b\u503c)\uff0c\u5f8c\u8005\u53ea\u662f\u67e5\u8a62\u4e0d\u6703\u6709\u4efb\u4f55\u66f4\u52d5\u3002Command Query Separation \u624b\u6cd5\u7684\u539f\u610f\u662f\u907f\u514d side-effect\uff0c\u4e0d\u8981\u540c\u6642\u4fee\u6539\u53c8\u67e5\u8a62\u72c0\u614b\uff0c\u4ee5\u65b9\u4fbf\u6e2c\u8a66\u53ca\u9664\u932f\u3002\u800c\u5728\u9019\u88e1\u900f\u904e\u9019\u500b\u624b\u6cd5\u4e5f\u53ef\u4ee5\u540c\u6642\u5e6b\u52a9\u6211\u5011\u601d\u8003 Tell, Don&#8217;t Ask\u3002<\/p>\n<p>\u5728 Smalltalk \u8a9e\u8a00\u4e2d\u7528 &#8220;message passsing&#8221; \u53d6\u4ee3 method calls \u4e00\u8a5e\uff0c\u9019\u8ddf Tell, Don&#8217;t Ask \u7684\u611f\u89ba\u985e\u4f3c\uff0c\u50cf\u662f\u9001\u8a0a\u606f\u800c\u4e0d\u662f\u57f7\u884c\u529f\u80fd\u3002\u5ef6\u4f38\u95b1\u8b80\u53ef\u4ee5\u770b\u770b The Pragmatic Bookshelf \u7684 <a href=\"http:\/\/www.pragprog.com\/articles\/tell-dont-ask\">Tell, Don\u2019t Ask<\/a> \u4e00\u6587\u3002<\/p>\n<h3>Substitute by Contract (\u53ef\u66ff\u63db\u7684\u5b50\u578b\u5225)<\/h3>\n<p>\u4e00\u500b\u4fdd\u6301\u7cfb\u7d71\u5f48\u6027\u7684\u95dc\u9375\uff0c\u5c31\u662f\u5c07\u65b0\u7a0b\u5f0f\u78bc\u66ff\u63db\u820a\u7a0b\u5f0f\u78bc\u7684\u6642\u5019\uff0c\u5176\u4ed6\u7a0b\u5f0f\u90fd\u7121\u9808\u66f4\u52d5\u3002\u6709\u4e00\u500b\u7269\u4ef6\u5c0e\u5411\u539f\u5247\u53ef\u4ee5\u5e6b\u52a9\u6211\u5011\uff1a Liskov&#8217;s Substitution principle (LSP) \u5b50\u578b\u5225\u5fc5\u9808\u53ef\u4ee5\u66ff\u63db\u4ed6\u5011\u7684\u7236\u578b\u5225\u3002\u63db\u53e5\u8a71\u8aaa\u4e5f\u5c31\u662f \u672c\u4f86\u4f7f\u7528\u57fa\u790e\u578b\u5225(Base class)\u51fd\u5f0f\u7684\u7a0b\u5f0f\uff0c\u5c31\u7b97\u63db\u6210\u884d\u751f\u985e\u5225(Derived class)\u4e2d\u4e5f\u4e0d\u9700\u4fee\u6539\u5c31\u53ef\u4ee5\u6b63\u5e38\u4f7f\u7528\u3002<\/p>\n<p>\u9055\u53cd LSP \u7684\u7684\u5f8c\u679c\u4e0d\u96e3\u60f3\u50cf\uff1a\u5047\u8a2d\u6709\u500b\u57fa\u790e\u578b\u5225 Base \u8ddf\u4ed6\u7684\u884d\u751f\u578b\u5225 Derived\uff0c\u800c\u6709\u500b\u51fd\u5f0f f \u53ef\u4ee5\u63a5\u53d7 Base \u985e\u5225\u7684\u7269\u4ef6\u7576\u4f5c\u53c3\u6578\uff0c\u63a5\u8457\u6211\u5011\u628a Derived \u8f49\u578b\u6210\u70ba Base \u4e4b\u5f8c\u4e1f\u9032 f \u88e1\u9762\uff0c\u5982\u679c\u6703\u7206\u70b8\u5c31\u8868\u793a Derived \u9055\u53cd LSP \u4e86\u3002\u9019\u6642\u5019 f \u7684\u4f5c\u8005\u70ba\u4e86\u4e0d\u8981\u7206\u70b8\uff0c\u6240\u4ee5\u53ea\u597d\u591a\u5beb\u578b\u5225\u5224\u65b7\u662f\u4e0d\u662f Dervied\uff0c\u65bc\u662f\u7a0b\u5f0f\u5c31\u8b8a\u9ad2\u4e86\u3002<\/p>\n<p>\u9055\u53cd LSP \u539f\u5247\uff0c\u4f60\u7684\u7e7c\u627f\u9ad4\u7cfb\u5373\u4f7f\u4ecd\u6709\u91cd\u7528\u6027\uff0c\u4f46\u537b\u958b\u59cb\u5931\u53bb\u64f4\u5145\u6027\uff0c\u56e0\u70ba\u985e\u5225\u7684\u7528\u6236\u5fc5\u9808\u77e5\u9053\u78ba\u5207\u7684\u578b\u5225\u624d\u80fd\u505a\u64cd\u4f5c\uff0c\u7576\u8981\u52a0\u5165\u65b0\u985e\u5225\u6642\u5c31\u8981\u5728\u7e7c\u627f\u9ad4\u7cfb\u4e2d\u4f86\u56de\u6aa2\u67e5\u3002<\/p>\n<p>\u53e6\u4e00\u7a2e\u9055\u53cd\u7684\u5f62\u5f0f\u662f\u884d\u751f\u985e\u5225\u6703\u4e1f\u51fa\u57fa\u790e\u985e\u5225\u4e0d\u6703\u4e1f\u51fa\u7684\u4f8b\u5916(exception)\uff0c\u9019\u6642\u5982\u679c\u57fa\u672c\u985e\u5225\u7684\u7528\u6236\u6c92\u6709\u9810\u671f\u5230\u9019\u7a2e\u60c5\u6cc1\uff0c\u90a3\u9ebc\u5728\u884d\u751f\u985e\u5225\u4e2d\u52a0\u5165\u9019\u4e9b\u4f8b\u5916\u5c31\u6703\u8b8a\u6210\u4e0d\u53ef\u66ff\u63db\u3002<\/p>\n<p>\u4f7f\u7528\u7269\u4ef6\u5c0e\u5411\u7684\u4e00\u500b\u5e38\u898b\u7684\u932f\u8aa4\uff0c\u5c31\u662f\u4e82\u7528\u7e7c\u627f\uff0c\u7136\u5f8c\u9055\u53cd LSP \u539f\u5247\u3002\u5982\u679c\u4f7f\u7528\u7e7c\u627f\uff0c\u4f46\u884d\u751f\u578b\u5225\u53c8\u6c92\u6709\u8981\u53ef\u4ee5\u66ff\u63db\u57fa\u790e\u578b\u5225\u4f86\u88ab\u64cd\u4f5c(\u4e5f\u5c31\u662f\u591a\u578b)\uff0c\u8acb\u60f3\u60f3\u662f\u4e0d\u662f\u9700\u8981\u7528\u5230\u7e7c\u627f\uff1f\u5982\u679c re-use \u57fa\u790e\u578b\u5225\u7684\u7a0b\u5f0f\u662f\u4f60\u4f7f\u7528\u7e7c\u627f\u7684\u539f\u56e0\uff0c\u90a3\u9ebc\u4f60\u4e5f\u61c9\u8a72\u8003\u616e\u4f7f\u7528 composition \u7d44\u5408\u95dc\u4fc2\uff0c\u8b93\u7269\u4ef6(Called class)\u64c1\u6709\u4e26\u4f7f\u7528\u53e6\u4e00\u500b\u7269\u4ef6(Delegate class)\uff0c\u4e5f\u5c31\u662f\u628a\u529f\u80fd\u59d4\u4ee3(delegation)\u51fa\u53bb\u3002\u800c\u4e0d\u662f\u8b93 Called Class \u53bb\u7e7c\u627f Base Class\u3002<\/p>\n<p>\u7e3d\u4e4b\u7d50\u8ad6\u5c31\u662f\uff1ais-a \u7684\u95dc\u4fc2\u7528\u7e7c\u627f(inheritance)\uff0chas-a \u6216 uses-a \u95dc\u4fc2\u7528\u59d4\u4ee3(delegation)\u3002<\/p>\n<p>\u95dc\u65bc LSP\uff0c\u5728<a href=\"http:\/\/www.books.com.tw\/exep\/assp.php\/ihower\/exep\/prod\/booksfile.php?item=0010293039\">\u654f\u6377\u8edf\u9ad4\u958b\u767c<\/a>\u4e00\u66f8\u4e2d\u6709\u5c08\u7ae0\u6bd4\u8f03\u6df1\u5165\u8ddf\u56b4\u8b39\u7684\u8a0e\u8ad6\uff0c\u50cf\u9019\u500b is-a \u5176\u5be6\u6709\u4e0d\u5c11\u8a8d\u77e5\u4e0a\u7684\u6a21\u7cca\u5730\u5e36 :p<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u8d81\u8457\u65b0\u5e74\u9023\u7e8c\u5047\u671f\uff0c\u7d42\u65bc\u628a\u9019\u4e00\u7ae0\u5ff5\u5b8c\u4e86\uff1a\u96a8\u8457\u958b\u767c\u7684\u9032\u5c55\uff0c\u7a0b\u5f0f\u9010\u6f38\u8b8a\u5f97\u602a\u7378\u3002\u9019\u7ae0\u8ac7\u5e7e\u500b\u91cd\u9ede\u5e6b\u52a9\u4f60\u8b93\u7a0b\u5f0f\u5bb9\u6613\u4e86\u89e3\u3001\u64f4 &hellip; <\/p>\n<p class=\"link-more\"><a href=\"https:\/\/ihower.tw\/blog\/1898-practices-of-an-agile-developer-4-programming\" class=\"more-link\">\u95b1\u8b80\u5168\u6587<span class=\"screen-reader-text\">\u3008\u5be6\u6230\u654f\u6377\u958b\u767c Practices of an Agile Developer (4) \u7a0b\u5f0f\u7bc7\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":[51,9],"tags":[],"class_list":["post-1898","post","type-post","status-publish","format-standard","hentry","category-agile","category-books","entry"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_shortlink":"https:\/\/wp.me\/p1q6tG-uC","jetpack_sharing_enabled":true,"jetpack_likes_enabled":true,"_links":{"self":[{"href":"https:\/\/ihower.tw\/blog\/wp-json\/wp\/v2\/posts\/1898","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=1898"}],"version-history":[{"count":66,"href":"https:\/\/ihower.tw\/blog\/wp-json\/wp\/v2\/posts\/1898\/revisions"}],"predecessor-version":[{"id":8275,"href":"https:\/\/ihower.tw\/blog\/wp-json\/wp\/v2\/posts\/1898\/revisions\/8275"}],"wp:attachment":[{"href":"https:\/\/ihower.tw\/blog\/wp-json\/wp\/v2\/media?parent=1898"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ihower.tw\/blog\/wp-json\/wp\/v2\/categories?post=1898"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ihower.tw\/blog\/wp-json\/wp\/v2\/tags?post=1898"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}