How to use php __set() method?

In PHP, the __set() method can be used to set values ​​for private member properties. It will be triggered when assigning a value to an undefined property; the syntax format is "__set($property, $value)", with Two parameters, the first parameter specifies the attribute name, the second parameter is the value to be set for the attribute, there is no return value.

Recommended: "PHP Video Tutorial"

Generally speaking, always define the attributes of a class as private , which is more in line with realistic logic. However, reading and assigning operations to attributes are very frequent, so in PHP5, two functions "__get()" and "__set()" are predefined to obtain and assign attributes.

• #__set() method is used to set private property values.
  

• #__get() method is used to get private property values.

In PHP5, we are provided with special methods for setting and obtaining values ​​for attributes, "__set()" and "__get()". These two methods It does not exist by default, but we add it to the class manually. Like the constructor method (__construct()), it will only exist if it is added to the class. You can add these two methods as follows, of course you can also press Add your own personal style:

//__set()方法用来设置私有属性
public function __set($name,$value){
$this->$name = $value;
}
//__get()方法用来获取私有属性
public function __get($name){
return $this->$name;
}

__get() method: This method is used to get the value of a private member attribute. It has a parameter. The parameter is passed in the name of the member attribute you want to get, and the obtained attribute value is returned. , we don’t need to call this method manually, because we can also make this method a private method, which is automatically called by the object when the private attribute is directly obtained. Because the private property has been encapsulated, the value cannot be obtained directly. However, if you add this method to the class, you will automatically obtain the value directly when using a statement such as "echo$p1->name". Call the __get($name) method and pass the attribute name to the parameter $name. Through the internal execution of this method, the value of the private attribute we passed in is returned. If the member properties are not encapsulated as private, the object itself will not automatically call this method.

__set( $property, $value ) method: This method is used to set values ​​for private member properties. It has two parameters. The first parameter is the name of the property you want to set the value for, and the second parameter The parameters are the values ​​to be set for the properties, and there is no return value. This method also does not need to be called manually. It can also be made private. It is automatically called when directly setting the private attribute value. The same private attribute has been encapsulated. If there is no __set() method, it is Not allowed, for example: $this->name='zhangsan', this will cause an error, but if you add the __set($property_name, $value) method to the class, when directly assigning values ​​to private properties , it will be called automatically, passing the attribute such as name to $property_name, and passing the value "zhangsan" to be assigned to $value. Through the execution of this method, the purpose of assignment is achieved. If the member properties are not encapsulated as private, the object itself will not automatically call this method. In order not to pass in illegal values, you can also make a judgment in this method. The code is as follows:

 <?php 
class Person 
{ 
//下面是人的成员属性，都是封装的私有成员 
private $name; //人的名子 
private $sex; //人的性别 
private $age; //人的年龄 
//__get()方法用来获取私有属性 
private function __get($property_name) 
{ 
echo "在直接获取私有属性值的时候，自动调用了这个__get()方法<br>"; 
if(isset($this->$property_name)) 
{ 
return($this->$property_name); 
} 
else 
{ 
return(NULL); 
} 
} 
//__set()方法用来设置私有属性 
private function __set($property_name, $value) 
{ 
echo "在直接设置私有属性值的时候，自动调用了这个__set()方法为私有属性赋值<br>"; 
$this->$property_name = $value; 
} 
} 
$p1=newPerson(); 
//直接为私有属性赋值的操作，会自动调用__set()方法进行赋值 
$p1->name="张三"; 
$p1->sex="男"; 
$p1->age=20; 
//直接获取私有属性的值，会自动调用__get()方法，返回成员属性的值 
echo "姓名：".$p1->name."<br>"; 
echo "性别：".$p1->sex."<br>"; 
echo "年龄：".$p1->age."<br>"; 
?>

Program execution result:

在直接设置私有属性值的时候，自动调用了这个__set()方法为私有属性赋值
在直接设置私有属性值的时候，自动调用了这个__set()方法为私有属性赋值
在直接设置私有属性值的时候，自动调用了这个__set()方法为私有属性赋值
在直接获取私有属性值的时候，自动调用了这个__get()方法
姓名：张三
在直接获取私有属性值的时候，自动调用了这个__get()方法
性别：男
在直接获取私有属性值的时候，自动调用了这个__get()方法
年龄：20

If the above code does not add the __get() and __set() methods, the program will error because it cannot be operated outside the class Private members, and the above code helps us directly access the encapsulated private members by automatically calling the __get() and __set() methods.

For more programming-related knowledge, please visit: Introduction to Programming! !

The above is the detailed content of How to use php __set() method?. For more information, please follow other related articles on the PHP Chinese website!