Note sharing about Object objects in PHP_PHP tutorial-PHP Tutorial-php.cn

Note sharing about Object objects in PHP_PHP tutorial

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Release： 2016-07-21 15:27:19

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1. When all instances are set to null, php will automatically clear the object references.

2. Constructor: __construct()

Method that is automatically executed when clearing the object: __destruct()

You can also set a method to manually clear the object: destroy or clean_up

3. Three types of variable scopes in objects: public, private and protected.

4. The constant attributes in the object can use the const keyword, and then be referenced in the format of "object name::property name" outside the object, and in the format of "self::property name" inside the object. .

5. Properties common to all instances of the entire object are static properties, using the static keyword.

The difference between static and const is that only the public keyword can be used before const, while static can use other keywords. In addition, the static attribute is not read-only.

6. The method that is common in all instances of the entire object is the static method, and the static keyword is also used.

7. You can define an abstract class to define the interface. Such classes can only be inherited, not instances created. Inside the class, use abstract to define the methods that subclasses must provide.

Any class with an abstract method must use the abstract keyword before the class name.

abstract class Producr

8. Adding the final keyword before the method can prevent subclasses from overriding this method.

You can also add the final keyword before the class name, which indicates that other classes cannot inherit it.

9. Interface interface is used to define the structure of a series of abstract classes.

interface IProduct
{
... ...
}

abstract class Product implements Iproduct
{
...
}

10.
== Compares whether two objects are of the same type and have the same value.
=== Compares whether two objects are instances of the same class.

11. Class cloning: completely copy the value.

$a = new SomeClass();
$b = clone $a;

You can define a __clone() function to customize the cloning behavior.

12. You can define the __toString() method of a class to customize the behavior of using print and echo functions.

13.get_class() function: Returns the class name of an object.

14. You can add a class name before the parameter of a function to indicate TypeHint.

15. You can define an __autoload() function, whose parameter is the class name that PHP cannot find defined. You can define how to load automatically in this function.