Understand 11 magic methods in PHP in one minute

We have learned so much about PHP. I wonder if you have fully mastered the 11 magic methods in PHP. If not, then follow this article to continue learning

1, __get, __set

These two methods are designed for properties that are not declared in the class and their parent class

• __get( $property ) This method is accessed when calling an undefined property
• __set( $property, $value ) Called when assigning a value to an undefined property

The no declaration here includes attributes whose access control is protected and private (that is, attributes that have no permission to access)

2, __isset, __unset

• __isset ( $property ) This method is called when the isset() function is called on an undefined property
• __unset( $property ) This method is called when the unset() function is called on an undefined property

The same as the __get method and __set method. The no declaration here includes attributes whose access control is protected and private (that is, attributes that have no permission to access)
3, __call

__call( $method, $arg_array ) This method is called when calling an undefined (including no permission to access) method

4, __autoload

__autoload function, automatically called when using a class that has not yet been defined. This function gives the scripting engine a last chance to load the required classes before PHP fails with an error.

Note: Exceptions thrown in the __autoload function cannot be caught by the catch statement block and result in a fatal error.

5, __construct, __destruct

• #__construct constructor method. This method is called when an object is created. The advantage is that the constructor method can have a unique Name, no matter what the name of the class it is in, so that when you change the name of the class, you do not need to change the name of the constructor method
• __destruct destructor method, PHP will use the destructor method before the object is destroyed (that is, from Call this method before clearing the memory code to clear memory. When PHP decides that your script is no longer associated with the object, the destructor will be called. Within a function's namespace, this will happen when the function returns. For global variables, this will happen on At the end of the script, if you want to explicitly destroy an object, you can assign any other value to the variable pointing to the object, usually assigning the variable to NULL or calling unset.

6, __clone

Object assignment in PHP5 uses reference assignment. When using the clone method to copy an object, the object will automatically call the __clone magic method. If Certain initialization operations need to be performed during object copying, which can be implemented in the __clone method.

7, __toString

#__toString method is automatically called when converting an object into a string. For example, when using echo to print an object, if the class does not implement this method, then The object cannot be printed through echo, otherwise it will display: Catchable fatal error: Object of class test could not be converted to string in, this method must return a string.

Before PHP 5.2.0, the __toString method can only take effect when used in conjunction with echo() or print(). After PHP 5.2.0, it can take effect in any string environment (for example, through printf(), using the %s modifier), but cannot be used in non-string environments (such as using the %d modifier). From PHP 5.2.0, if an object that does not define the __toString method is converted to a string, an E_RECOVERABLE_ERROR error will be reported.

8, __sleep, __wakeup

__sleep is used during serialization and

__wakeup is called during deserialization.
• serialize() checks whether there is a function with the magic name __sleep in the class. If so, the function will run before any serialization. It clears the object and should return an array containing the names of all variables in the object that should be serialized.
• The purpose of using __sleep is to close any database connections the object may have, submit pending data, or perform similar cleanup tasks. In addition, this function is also useful if you have very large objects that do not need to be stored completely.

Conversely, unserialize() checks for the existence of a function with the magic name __wakeup. This function can reconstruct any resources the object may have, if present. The purpose of using __wakeup is to reestablish any database connections that may have been lost during serialization and to handle other reinitialization tasks.

9, __set_state

When var_export() is called, this static method will be called (valid since PHP 5.1.0). The only parameter of this method is an array containing class properties arranged in the format of array('property' => value, ...).

10, __invoke

When trying to call an object by calling a function, the __invoke method will be automatically called. Valid for PHP5.3.0 or above
11, __callStatic

It works similar to the __call() magic method, __callStatic() is to handle static method calls, PHP5.3.0 The above version works, PHP does tighten the definition of the __callStatic() method; it must be public, and must be declared static. Likewise, the __call() magic method must be defined as public, as must all other magic methods.

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