


The example in this article describes the use of PHP reflection learning to instantiate class operations without the new method. I share it with you for your reference. The details are as follows:
The previous article on PHP Reflection Getting Started Example briefly introduced how to use several common classes of PHP reflection, but you may still not be able to imagine what you can do with reflection. Come on,
Next I will use the reflection class to do something. Everyone knows that you need to use the new keyword to instantiate a class. Is it okay without using new
? The answer is yes, it can be achieved using reflection:
Related learning recommendations: PHP programming from entry to proficiency
First create a file student .php:
<?php class Student { public $id; public $name; public function __construct($id,$name) { $this->id = $id; $this->name = $name; } public function study() { echo $this->name.' is learning.....'.PHP_EOL; } public function showBag(){ echo "My bag have ".$this->bag->all(); } }
Create a new file run.php
<?php require 'student.php'; function make($class, $vars = []) { $ref = new ReflectionClass($class); if(!$ref->isInstantiable()) { throw new Exception("类{$class} 不存在"); } $constructor = $ref->getConstructor(); if(is_null($constructor)) { return new $class; } $params = $constructor->getParameters(); $resolveParams = []; foreach ($params as $key=>$value) { $name = $value->getName(); if(isset($vars[$name])) { $resolveParams[] = $vars[$name]; } else { $default = $value->isDefaultValueAvailable() ? $value->getDefaultValue() : null; if(is_null($default)) { if($value->getClass()) { $resolveParams[] = make($value->getClass()->getName(), $vars); } else { throw new Exception("{$name} 没有传值且没有默认值。"); } } else { $resolveParams[] = $default; } } } return $ref->newInstanceArgs($resolveParams); }
run.php. The make function is the function we write to instantiate the class. The first parameter is passed in the class name. , the second parameter is the parameter data that needs to be passed in to the constructor of the class.
There are several situations depending on the parameters of Student's constructor: (The following code, please append it to run.php according to different situations)
Case 1: No $ is provided The value of name
try { $stu = make('Student', ['id' => 1]); print_r($stu); $stu->study(); } catch (Exception $e) { echo $e->getMessage(); }
When $name does not have a default value in the constructor, an error will be reported. You can slightly modify the Student class to provide a default value for $name, and then it will not An error was reported.
Case 2 provides the value of $name
try { $stu = make('Student', ['id' => 1, 'name' => 'li']); print_r($stu); $stu->study(); } catch (Exception $e) { echo $e->getMessage(); }
Case 3, let’s change student.php
<?php class Bag{ public function name(){ return "学生包".PHP_EOL; } } class Student { public $id; public $name; public function __construct($id, $name="xxx", Bag $bag) { $this->id = $id; $this->name = $name; $this->bag = $bag; } public function study() { echo $this->name.' is learning.....'.PHP_EOL; } public function showBag(){ echo "My bag is ".$this->bag->name(); } }
As you can see, a parameter $bag is added to the Student class, the type is Bag
Run it now
<?php try { $stu = make('Student', ['id' => 1, 'name' => 'li']); print_r($stu); $stu->study(); $stu->showBag(); } catch (Exception $e) { echo $e->getMessage(); }
You can see that the third parameter $bag of the constructor is automatically instantiated ified, and then passed to the constructor of the Student class. This part is very critical. This place can be used to implement dependency injection. We do not have to manually instantiate the object. We can automatically instantiate the object according to the corresponding class of the parameter. This achieves decoupling between classes. If you have learned Laravel, you should be familiar with this.
The above is the detailed content of A direct look at PHP reflection learning to instantiate class operations without using the new method. For more information, please follow other related articles on the PHP Chinese website!

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php除以100保留两位小数的方法:1、利用“/”运算符进行除法运算,语法“数值 / 100”;2、使用“number_format(除法结果, 2)”或“sprintf("%.2f",除法结果)”语句进行四舍五入的处理值,并保留两位小数。

判断方法:1、使用“strtotime("年-月-日")”语句将给定的年月日转换为时间戳格式;2、用“date("z",时间戳)+1”语句计算指定时间戳是一年的第几天。date()返回的天数是从0开始计算的,因此真实天数需要在此基础上加1。

php判断有没有小数点的方法:1、使用“strpos(数字字符串,'.')”语法,如果返回小数点在字符串中第一次出现的位置,则有小数点;2、使用“strrpos(数字字符串,'.')”语句,如果返回小数点在字符串中最后一次出现的位置,则有。

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方法:1、用“str_replace(" ","其他字符",$str)”语句,可将nbsp符替换为其他字符;2、用“preg_replace("/(\s|\ \;||\xc2\xa0)/","其他字符",$str)”语句。

在php中,可以使用substr()函数来读取字符串后几个字符,只需要将该函数的第二个参数设置为负值,第三个参数省略即可;语法为“substr(字符串,-n)”,表示读取从字符串结尾处向前数第n个字符开始,直到字符串结尾的全部字符。


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