


PHP autoload running mechanism example analysis, autoload example analysis_PHP tutorial
PHP autoload operating mechanism example analysis, autoload example analysis
This article provides a more in-depth analysis of PHP’s autoload operating mechanism. It is helpful to deeply understand the operating principles of PHP. The specific analysis is as follows:
There are two ways to implement autoload in PHP:
1. Interceptor__autoload()
2. Set the global variable function pointer autoload_func to the specified function. Usually used in c extensions
Essentially, the former is achieved through the latter.
Analysis process, PHP5.3.6 source code:
=>Zend/zend_vm_def.h Line 1894
ZEND_VM_HANDLER(109,ZEND_FETCH_CLASS,...
=>zend_execute_API.c line 1526
zend_class_entry *zend_fetch_class(const char *class_name,...
=>zend_execute_API.c line 1564
if(zend_lookup_class_ex(class_name,class_name_len,...
=>zend_execute_API.c line 1039
ZEND_API int zend_lookup_class_ex(const char *na...
=>zend_execute_API.c line 1121
retval = zend_call_function(&fcall_info, &fcall_cache TSRMLS_CC);
=>zend_execute_API.c line 758
zend_call_function
As the name suggests, the main function of zend_call_function is to call PHP functions. Its parameters fcall_info and fcall_cache point to two important structures respectively, zend_fcall_info and zend_fcall_info_cache
The main workflow of zend_call_function is as follows:
If fcall_cache.function_handler is not NULL, execute the function pointed to by fcall_cache.function_handler directly.
If fcall_cache.function_handler is NULL, try to find a function named fcall_info.function_name, and if it exists, execute it;
The summary is as follows. The main execution process of the autoload mechanism is:
(1) Check whether the executor global variable function pointer autoload_func is NULL.
(2) If autoload_func is not NULL, the function pointed to by the autoload_func pointer is directly executed to load the class without checking whether the __autoload() function is defined.
(3) If autoload_func is NULL, check whether the __autoload() function is defined in the system. If it is not defined, an error is reported and exits; if the __autoload() function is defined, __autoload() is executed to try to load the class and the loading result is returned.
Automatic loading facilitates object-oriented and code reuse, but different __autoloads in multiple class libraries can cause confusion. It can be solved with spl_autoload, which registers the interceptor functions of different developers into the hashtable of the automatic loading function. The mechanism of spl to implement automatic loading is to maintain a hashtable, which stores various functions with automatic loading function.
When the automatic loading mechanism is triggered, zend will traverse and execute the functions in this hashtable until the class is successfully loaded or returns after the loading fails.
When you need to use the autoload function, use the function spl_autoload_register() or spl_autoload_register('autoloadfuncitonname')
spl_autoload_register() without parameters will load the spl_autoload() function by default. This function has limited functions and can only search for the class library with the specified extension in inlcude_path.
The spl_autoload_register() with parameters no longer loads the spl_autoload() function by default.
You can view the functions in the current autoload hashtable through spl_autoload_functions(), which returns an array
Note: When using spl_autoload, the system will ignore the interceptor __autoload unless it is explicitly added to the hashtable using spl_autoload_register('__autoload')
I hope this article will be helpful to everyone’s PHP programming
Let me share with you what I am using
//Automatically mount class function AutoLoad($classname){ // class $filepath = BASE_CLASS . $classname . '.class.php'; if (file_exists ($filepath)) { return include $filepath; } //lib library file $filepath = BASE_LIB . $classname . '.lib.php'; if (file_exists($filepath)) { return include $filepath; }}spl_autoload_register( 'AutoLoad'); Usage:
//Check login User::is_loginin();//Automatically instantiate User and execute is_loginin
__autoload is commonly used in automatic loading of class libraries
This is the method mentioned on the Internet. According to the class name, find the class file, and then require_one
spl_autoload_register()
The biggest flaw of __autoload is that it cannot Multiple autoload methods
Okay, think about the following scenario. Your project references a project of someone else. There is an __autoload in your project, and another person’s project also has an __autoload, so there are two __autoload conflicts. The solution is to modify __autoload to become one, which is undoubtedly very cumbersome.
Therefore, we urgently need to use an autoload call stack, so that the autoload series functions of spl appear. You can use spl_autoload_register to register multiple custom autoload functions
If your PHP version is greater than 5.1, you can use spl_autoload

PHP is used to build dynamic websites, and its core functions include: 1. Generate dynamic content and generate web pages in real time by connecting with the database; 2. Process user interaction and form submissions, verify inputs and respond to operations; 3. Manage sessions and user authentication to provide a personalized experience; 4. Optimize performance and follow best practices to improve website efficiency and security.

PHP uses MySQLi and PDO extensions to interact in database operations and server-side logic processing, and processes server-side logic through functions such as session management. 1) Use MySQLi or PDO to connect to the database and execute SQL queries. 2) Handle HTTP requests and user status through session management and other functions. 3) Use transactions to ensure the atomicity of database operations. 4) Prevent SQL injection, use exception handling and closing connections for debugging. 5) Optimize performance through indexing and cache, write highly readable code and perform error handling.

Using preprocessing statements and PDO in PHP can effectively prevent SQL injection attacks. 1) Use PDO to connect to the database and set the error mode. 2) Create preprocessing statements through the prepare method and pass data using placeholders and execute methods. 3) Process query results and ensure the security and performance of the code.

PHP and Python have their own advantages and disadvantages, and the choice depends on project needs and personal preferences. 1.PHP is suitable for rapid development and maintenance of large-scale web applications. 2. Python dominates the field of data science and machine learning.

PHP is widely used in e-commerce, content management systems and API development. 1) E-commerce: used for shopping cart function and payment processing. 2) Content management system: used for dynamic content generation and user management. 3) API development: used for RESTful API development and API security. Through performance optimization and best practices, the efficiency and maintainability of PHP applications are improved.

PHP makes it easy to create interactive web content. 1) Dynamically generate content by embedding HTML and display it in real time based on user input or database data. 2) Process form submission and generate dynamic output to ensure that htmlspecialchars is used to prevent XSS. 3) Use MySQL to create a user registration system, and use password_hash and preprocessing statements to enhance security. Mastering these techniques will improve the efficiency of web development.

PHP and Python each have their own advantages, and choose according to project requirements. 1.PHP is suitable for web development, especially for rapid development and maintenance of websites. 2. Python is suitable for data science, machine learning and artificial intelligence, with concise syntax and suitable for beginners.

PHP is still dynamic and still occupies an important position in the field of modern programming. 1) PHP's simplicity and powerful community support make it widely used in web development; 2) Its flexibility and stability make it outstanding in handling web forms, database operations and file processing; 3) PHP is constantly evolving and optimizing, suitable for beginners and experienced developers.


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