以OOP之名--重构PHP代码小教程(0)

前言：由于一些历史原因，偶尔还是会遇到一些陈年老码，笔者学习PHP的过程中第二个阶段就重构了一些项目实战的源代码（基于PHP4+HMTL4的改成PHP7+HTML5）。就目前业界而言，多数PHP网站只是一锤子买卖--业者花一次钱，之后就要求跑一万年，因此至今仍然有一些基于PHP4、PHP5、HTML4的项目在运行。但是，针对一些需要更新后续的网站，要么第一次创建时需要考虑选择MVC框架，要么就需要重构PHP代码。

关于重构，不同人有不同观点：OOP化，函数更新，函数签名重置，MVC化，等等。

本将着重在OOP化上，以2个例子TennisGame以及Insturance为例子一步一步演示如何进行OOP重构。

案例一：网球小案例 tennisgame.php

这里是个非OOP的小代码，后续会基于该代码进行修改。可以看得出除了class、new一类的内容，代码本身几乎没有什么OOP的内容。

<?php class TennisGame{ public $score = ''; public function getScore($player1Name, $player2Name, $p1Score, $p2Score){ if($p1Score == $p2Score){ switch($p1Score){ case 0: $this->score = 'Love-All'; break; case 1: $this->score = 'Fifteen-All'; break; case 2: $this->score = 'Thirty-All'; break; case 3: $this->score = 'Forty-All'; break; default: $this->score = 'Deuce'; break; } } else if($p1Score >= 4 || $p2Score >=4 ){ $nimusResult = $p1Score - $p2Score; if($minusResult == 1) $this->score = "Advantange" . $player1Name; else if($minusResult == -1) $this->score = "Advantange" . $player2Name; else if ($minusResult >= 2) $this->score = "Win for" . $player1Name; else $this->score = "Win for" . $player2Name; }else{ for($i = 1;$i < 3; $i ++){ if($i == 1) $tempScore = $p1Score; else { $this->score .="-"; $tempScore = $p2Score; } switch($tempScore){ case 0: $this->score .="Love"; break; case 1: $this->score .="Fifteen"; break; case 2: $this->score .="Thirty"; break; case 3: $this->score .="Forty"; break; } } } } public function __toString(){ return $this->score; } } $tennisGame = new TennisGame(); $tennisGame->getScore('one','two',2,3); echo $tennisGame; ?>

命令行php tennisgame.php

返回Thirty-Forty

Step 0 ： getScore，常见的getter就是用来返回值的，这里的最后一行就变得多余了，以echo替换，进而，toString()也变得多余了：

<?php class TennisGame{ public $score = ''; public function getScore($player1Name, $player2Name, $p1Score, $p2Score){ if($p1Score == $p2Score){ switch($p1Score){ case 0: $this->score = 'Love-All'; break; case 1: $this->score = 'Fifteen-All'; break; case 2: $this->score = 'Thirty-All'; break; case 3: $this->score = 'Forty-All'; break; default: $this->score = 'Deuce'; break; } } else if($p1Score >= 4 || $p2Score >=4 ){ $nimusResult = $p1Score - $p2Score; if($minusResult == 1) $this->score = "Advantange" . $player1Name; else if($minusResult == -1) $this->score = "Advantange" . $player2Name; else if ($minusResult >= 2) $this->score = "Win for" . $player1Name; else $this->score = "Win for" . $player2Name; }else{ for($i = 1;$i < 3; $i ++){ if($i == 1) $tempScore = $p1Score; else { $this->score .="-"; $tempScore = $p2Score; } switch($tempScore){ case 0: $this->score .="Love"; break; case 1: $this->score .="Fifteen"; break; case 2: $this->score .="Thirty"; break; case 3: $this->score .="Forty"; break; } } } return $this->score; } } $tennisGame = new TennisGame(); echo $tennisGame->getScore('one','two',2,3); ?>

Step 1:认真考虑变量是否是类变量还是方法的局部变量

关于局部变量还是类变量，没有一个统一的概念。在这里，我们姑且把类变量$score修改成局部变量

<?php class TennisGame{ public function getScore($player1Name, $player2Name, $p1Score, $p2Score){ $score = ''; if($p1Score == $p2Score){ switch($p1Score){ case 0: $score = 'Love-All'; break; case 1: $score = 'Fifteen-All'; break; case 2: $score = 'Thirty-All'; break; case 3: $score = 'Forty-All'; break; default: $score = 'Deuce'; break; } } else if($p1Score >= 4 || $p2Score >=4 ){ $nimusResult = $p1Score - $p2Score; if($minusResult == 1) $score = "Advantange" . $player1Name; else if($minusResult == -1) $score = "Advantange" . $player2Name; else if ($minusResult >= 2) $score = "Win for" . $player1Name; else $score = "Win for" . $player2Name; }else{ for($i = 1;$i < 3; $i ++){ if($i == 1) $tempScore = $p1Score; else { $score .="-"; $tempScore = $p2Score; } switch($tempScore){ case 0: $score .="Love"; break; case 1: $score .="Fifteen"; break; case 2: $score .="Thirty"; break; case 3: $score .="Forty"; break; } } } return $score; } } $tennisGame = new TennisGame(); echo $tennisGame->getScore('one','two',2,3); ?>

step 2:提早return原则

提早return原则是一般写程序时一个常见的优化原则，把能return的放到if语句块中，尽早return。

<?php class TennisGame{ public function getScore($player1Name, $player2Name, $p1Score, $p2Score){ $score = ''; if($p1Score == $p2Score){ switch($p1Score){ case 0: $score = 'Love-All'; break; case 1: $score = 'Fifteen-All'; break; case 2: $score = 'Thirty-All'; break; case 3: $score = 'Forty-All'; break; default: $score = 'Deuce'; break; } return $score; } if($p1Score >= 4 || $p2Score >=4 ){ $nimusResult = $p1Score - $p2Score; if($minusResult == 1) $score = "Advantange" . $player1Name; else if($minusResult == -1) $score = "Advantange" . $player2Name; else if ($minusResult >= 2) $score = "Win for" . $player1Name; else $score = "Win for" . $player2Name; return $score; } for($i = 1;$i < 3; $i ++){ if($i == 1) $tempScore = $p1Score; else { $score .="-"; $tempScore = $p2Score; } switch($tempScore){ case 0: $score .="Love"; break; case 1: $score .="Fifteen"; break; case 2: $score .="Thirty"; break; case 3: $score .="Forty"; break; } } return $score; } // public function __toString(){ // return $this->score; // } } $tennisGame = new TennisGame(); echo $tennisGame->getScore('one','two',2,3); // echo $tennisGame; ?>