


PHP object-oriented abstract methods and abstract classes __call detailed tutorial on cloning objects_PHP tutorial
This article introduces the object-oriented abstract method and abstract class __call clone object usage in PHP. Friends who need to know how to do it can learn it.
Abstract methods and abstract classes
In OOP language, a class can have one or more subclasses, and each class has at least one public method as an interface for external code to access it. Abstract methods are introduced to facilitate inheritance. Let's first take a look at the definitions of abstract classes and abstract methods before explaining their uses.
What is an abstract method? The method we define in the class without a method body is an abstract method. The so-called no method body means that when the method is declared, there are no curly brackets and its contents. Instead, a parentheses is added directly after the method name when declaring it. ends with the number, and when declaring an abstract method, add a keyword "abstract" to modify it; for example:
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abstract function fun2(); |
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abstract class Demo abstract function fun1(); |
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abstract class Demo
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abstract class Demo { var $test; abstract function fun1(); abstract function fun2(); Function fun3() { ... ... } } |
//Abstract classes can generate instance objects, so this is wrong. The instantiated objects are handed over to subclasses
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class Test extends Demo
Function fun1() { ... ... }
function fun2()
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//Subclasses can instantiate objects because they implement all abstract methods in the parent class
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//这是一个测试的类,里面没有属性和方法 //产生一个Test类的对象 //调用对象里不存在的方法 //程序不会退出可以执行到这里 |
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//This is a test class, there are no attributes and methods in it class Test { } //Generate an object of Test class $test=new Test(); //Call a method that does not exist in the object $test->demo("one", "two", "three"); //The program will not execute here echo "this is a test"; |
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//This is a test class, there are no attributes and methods in it class Test { //Method that is automatically called when calling a non-existing method. The first parameter is the method name, and the second parameter is the array parameter Function __call($function_name, $args) { print "The function you called: $function_name(parameter: "; print_r($args); Print ") does not exist! N"; } } //Generate an object of Test class $test=new Test(); //Call a method that does not exist in the object $test->demo("one", "two", "three"); //The program will not exit and can be executed here echo "this is a test"; |
The output result of the above example is:
The function you called: demo (parameter: Array ( [0] => one [1] => two [2] => three ) ) does not exist! this is a test.
Clone Object
Sometimes we need to use two or more identical objects in a project. If you use the "new" keyword to recreate the object and then assign the same attributes, this is more cumbersome and error-prone, so It is very necessary to completely clone an identical object from an object, and after cloning, the two objects will not interfere with each other.
In PHP5 we use the "clone" keyword to clone objects;
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PHP5 defines a special method name "__clone()" method, which is automatically called when an object is cloned. Using the "__clone()" method will create an object with the same attributes and methods as the original object. If If you want to change the contents of the original object after cloning, you need to rewrite the original properties and methods in __clone(). The "__clone()" method can have no parameters. It automatically contains two pointers, $this and $that, and $this points to copy, and $that points to the original;
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class Person | {
var $age; //The person’s age
} //Method automatically called when an object is cloned. If you want to change the content of the original object after cloning, you need to rewrite the original attributes and methods in __clone()
Reasons for PHPSession failure include configuration errors, cookie issues, and session expiration. 1. Configuration error: Check and set the correct session.save_path. 2.Cookie problem: Make sure the cookie is set correctly. 3.Session expires: Adjust session.gc_maxlifetime value to extend session time.

Methods to debug session problems in PHP include: 1. Check whether the session is started correctly; 2. Verify the delivery of the session ID; 3. Check the storage and reading of session data; 4. Check the server configuration. By outputting session ID and data, viewing session file content, etc., you can effectively diagnose and solve session-related problems.

Multiple calls to session_start() will result in warning messages and possible data overwrites. 1) PHP will issue a warning, prompting that the session has been started. 2) It may cause unexpected overwriting of session data. 3) Use session_status() to check the session status to avoid repeated calls.

Configuring the session lifecycle in PHP can be achieved by setting session.gc_maxlifetime and session.cookie_lifetime. 1) session.gc_maxlifetime controls the survival time of server-side session data, 2) session.cookie_lifetime controls the life cycle of client cookies. When set to 0, the cookie expires when the browser is closed.

The main advantages of using database storage sessions include persistence, scalability, and security. 1. Persistence: Even if the server restarts, the session data can remain unchanged. 2. Scalability: Applicable to distributed systems, ensuring that session data is synchronized between multiple servers. 3. Security: The database provides encrypted storage to protect sensitive information.

Implementing custom session processing in PHP can be done by implementing the SessionHandlerInterface interface. The specific steps include: 1) Creating a class that implements SessionHandlerInterface, such as CustomSessionHandler; 2) Rewriting methods in the interface (such as open, close, read, write, destroy, gc) to define the life cycle and storage method of session data; 3) Register a custom session processor in a PHP script and start the session. This allows data to be stored in media such as MySQL and Redis to improve performance, security and scalability.

SessionID is a mechanism used in web applications to track user session status. 1. It is a randomly generated string used to maintain user's identity information during multiple interactions between the user and the server. 2. The server generates and sends it to the client through cookies or URL parameters to help identify and associate these requests in multiple requests of the user. 3. Generation usually uses random algorithms to ensure uniqueness and unpredictability. 4. In actual development, in-memory databases such as Redis can be used to store session data to improve performance and security.

Managing sessions in stateless environments such as APIs can be achieved by using JWT or cookies. 1. JWT is suitable for statelessness and scalability, but it is large in size when it comes to big data. 2.Cookies are more traditional and easy to implement, but they need to be configured with caution to ensure security.


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