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A preliminary exploration of PHP magic functions (1)_PHP tutorial
- WBOYOriginal
- 2016-07-15 13:24:36801browse
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(); |
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"; } } $t = new Test();将会输出end |
We can perform operations such as releasing resources at the end of the object operation
3.__get() When trying to read an object that does not exist attribute is called.
If you try to read a property that does not exist in an object, PHP will give an error message. If we add the __get method to the class, we can use this function to implement various operations similar to reflection in Java.
class Test { public function __get($key) { echo $key . " 不存在"; } } $t = new Test(); echo $t->name; 就会输出：name 不存在 |
4.__set() is called when trying to write a value to a property that does not exist.
class Test { public function __set($key,$value) { echo '对'.$key . "附值".$value; } } $t = new Test(); $t->name = "aninggo"; 就会输出：对 name 附值 aninggo |
5.__call() This method is called when trying to call a method that does not exist on the object.
class Test { public function __call($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); |
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; |
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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