Magic methods in PHP5

Magic function

1. __construct()
is called when instantiating an object.
When __construct and a function with the class name and function name exist at the same time, __construct will be called and the other one will not be called.

2. __destruct()
Called when an object is deleted or the object operation terminates.

3. __call()
The object calls a certain method.
If the method exists, it will be called directly;
If it does not exist, the __call function will be called.

4. __get()
When reading the attributes of an object,
If the attribute exists, the attribute value will be returned directly;
If it does not exist, the __get function will be called.

5. __set()
When setting the attributes of an object,
If the attribute exists, the value will be assigned directly;
If it does not exist, the __set function will be called.

6. __toString()
Called when printing an object. Such as echo $obj; or print $obj;

7. __clone()
Called when cloning an object. For example: $t=new Test();$t1=clone $t;

8. __sleep()
is called before serialize. If the object is relatively large and you want to delete a little bit before serializing it, you can consider this function.

9. __wakeup() is called when unserialize and does some object initialization work.

10. __isset()

Called when checking whether an object's attributes exist. For example: isset($c->name).

11. __unset()

Called when unsetting a property of an object. For example: unset($c->name).

12. __set_state()

Called when var_export is called. Use the return value of __set_state as the return value of var_export.

13. __autoload()

When instantiating an object, if the corresponding class does not exist, this method is called.

Magic Constant

1. __LINE__

Returns the current line number in the file.

2. __FILE__

Returns the full path and file name of the file. If used in an include file, returns the include file name. As of PHP 4.0.2, __FILE__ always contains an absolute path, while versions before that sometimes contained a relative path.

3. __FUNCTION__

Returns the function name (newly added in PHP 4.3.0). Since PHP 5 this constant returns the name of the function as it was defined (case sensitive). In PHP 4 this value is always lowercase.

4. __CLASS__

Returns the name of the class (new in PHP 4.3.0). Since PHP 5 this constant returns the name of the class when it was defined (case sensitive). In PHP 4 this value is always lowercase.

5. __METHOD__

Returns the method name of the class (newly added in PHP 5.0.0). Returns the name of the method as it was defined (case-sensitive).

(1) First introduction to magic methods
Php5.0 has provided us with many object-oriented features since its release, especially many easy-to-use magic methods. These magic methods can allow us to simplify our coding and make our coding more convenient. Design our systems well. Today we will learn about the magic methods provided by php5.0.