A preliminary exploration of PHP magic functions (1)

A preliminary exploration of PHP magic functions (1)_PHP tutorial

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Release： 2016-07-15 13:24:36

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Php5.0 has provided us with many object-oriented features since its release, especially many easy-to-use magic methods. These magic methods allow us to simplify our coding and better design our system. Today we will learn about the magic methods provided by php5.0.

1.__construct() When instantiating an object, this method of the object is first called.

class Test {  function __construct()  {   echo "before";  } } $t = new Test();

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The output is:

start
We know that the php5 object model and the function with the same class name are the constructors of the class, so if we define both For constructors and __construct() methods, php5 will call the constructor by default instead of calling the __construct() function, so __construct() serves as the default constructor of the class

2.__destruct () This method is called when an object is deleted or when the object operation terminates.

class Test {  function __destruct()  {   echo "end";  } } $t = new Test();将会输出end

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We can perform operations such as releasing resources at the end of the object operation

3.__get() When trying to read an object that does not exist attribute is called.

If you try to read a property that does not exist in an object, PHP will give an error message. If we add the __get method to the class, we can use this function to implement various operations similar to reflection in Java.

class Test {  public function __get($key)  {   echo $key . " 不存在";  } } $t = new Test(); echo $t->name; 就会输出：name 不存在

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4.__set() is called when trying to write a value to a property that does not exist.

class Test {  public function __set($key,$value)  {   echo '对'.$key . "附值".$value;  } } $t = new Test(); $t->name = "aninggo"; 就会输出：对 name 附值 aninggo

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5.__call() This method is called when trying to call a method that does not exist on the object.

class Test {  public function __call($Key, $Args)  {   echo "您要调用的 {$Key} 方法不存在。你传入的参数是：" . print_r($Args, true);  } } $t = new Test(); $t->getName(aning,go);

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The program will output:
The getName method you want to call does not exist. The parameters are: Array
(
[0] => aning
[1] => go
)

6.__toString() when printing an object Called

This method is similar to java's toString method. When we print the object directly, this function is called back.

class Test {  public function __toString()  {   return "打印 Test";  } } $t = new Test(); echo $t;

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When running echo $t; , $t->__toString(); will be called to output
Print Test

7.__clone() When the object is cloned, it will be called

class Test {  public function __clone()  {   echo "我被复制了！";  } }$t = new Test(); $t1 = clone $t;程序输出：我被克隆了！

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