php static delayed static binding_PHP tutorial
If you are a lazy programmer, you may be annoyed when you see the following code
abstract class U{
}
class u1 extends U{
public static function create(){
return new u1();
}
}
class u2 extends U{
public static function create(){
return new u2();
}
}
There is no problem for this code to work normally, but a large amount of repeated code will be very annoying
I don’t want to add a create method in each subclass. If I put the create method in the super class U, the code may be
abstract class U{
public static function create(){
return new self();
}
}
class u1 extends U{
Function a(){}
}
class u2 extends U{
}
u1::create();
It looks very elegant and neat, now we put the common code in one place and use self as a reference to the class. But here we make an assumption about self.
In fact, the role of self on the class is not exactly the same as the role of $this on the object. self does not refer to the calling context, it refers to the parsing context, so if you run the above example, you will get
Fatal error: Cannot instantiate abstract class U in D:wampwwwtestoopstatic.php on line 21
Therefore self is resolved to the U that defines create, rather than to the u1 class that calls self.
Before php5.3, there were strict restrictions in this regard, resulting in many clumsy solutions. php5.3 introduced delayed static binding and the use of keyword static
Static is similar to self, but it refers to the called class rather than the containing class.
In the following example u1::create will generate the u1 object instead of instantiating the U object
abstract class U{
public static function create(){
Return new static();
}
}
class u1 extends U{
}
class u2 extends U{
}
u1::create();
Static can not only be used for instantiation, but like self and parent, it can also be used as a calling identifier for static methods, even calling from a non-static context
abstract class U{
private $group;
public function __construct(){
$this->group=static::getGroup();
}
public static function create(){
Return new static();
}
static function getGroup(){
return 'default';
}
}
class u1 extends U{
}
class u2 extends U{
static function getGroup(){
return 'u2';
}
}
class u3 extends u2{
}
print_r(u1::create());
echo '
';
print_r(u3::create());
u1 Object ( [group:U:private] => default )
u3 Object ( [group:U:private] => u2 )

What’s still popular is the ease of use, flexibility and a strong ecosystem. 1) Ease of use and simple syntax make it the first choice for beginners. 2) Closely integrated with web development, excellent interaction with HTTP requests and database. 3) The huge ecosystem provides a wealth of tools and libraries. 4) Active community and open source nature adapts them to new needs and technology trends.

PHP and Python are both high-level programming languages that are widely used in web development, data processing and automation tasks. 1.PHP is often used to build dynamic websites and content management systems, while Python is often used to build web frameworks and data science. 2.PHP uses echo to output content, Python uses print. 3. Both support object-oriented programming, but the syntax and keywords are different. 4. PHP supports weak type conversion, while Python is more stringent. 5. PHP performance optimization includes using OPcache and asynchronous programming, while Python uses cProfile and asynchronous programming.

PHP is mainly procedural programming, but also supports object-oriented programming (OOP); Python supports a variety of paradigms, including OOP, functional and procedural programming. PHP is suitable for web development, and Python is suitable for a variety of applications such as data analysis and machine learning.

PHP originated in 1994 and was developed by RasmusLerdorf. It was originally used to track website visitors and gradually evolved into a server-side scripting language and was widely used in web development. Python was developed by Guidovan Rossum in the late 1980s and was first released in 1991. It emphasizes code readability and simplicity, and is suitable for scientific computing, data analysis and other fields.

PHP is suitable for web development and rapid prototyping, and Python is suitable for data science and machine learning. 1.PHP is used for dynamic web development, with simple syntax and suitable for rapid development. 2. Python has concise syntax, is suitable for multiple fields, and has a strong library ecosystem.

PHP remains important in the modernization process because it supports a large number of websites and applications and adapts to development needs through frameworks. 1.PHP7 improves performance and introduces new features. 2. Modern frameworks such as Laravel, Symfony and CodeIgniter simplify development and improve code quality. 3. Performance optimization and best practices further improve application efficiency.

PHPhassignificantlyimpactedwebdevelopmentandextendsbeyondit.1)ItpowersmajorplatformslikeWordPressandexcelsindatabaseinteractions.2)PHP'sadaptabilityallowsittoscaleforlargeapplicationsusingframeworkslikeLaravel.3)Beyondweb,PHPisusedincommand-linescrip

PHP type prompts to improve code quality and readability. 1) Scalar type tips: Since PHP7.0, basic data types are allowed to be specified in function parameters, such as int, float, etc. 2) Return type prompt: Ensure the consistency of the function return value type. 3) Union type prompt: Since PHP8.0, multiple types are allowed to be specified in function parameters or return values. 4) Nullable type prompt: Allows to include null values and handle functions that may return null values.


Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Article

Hot Tools

Notepad++7.3.1
Easy-to-use and free code editor

Dreamweaver Mac version
Visual web development tools

ZendStudio 13.5.1 Mac
Powerful PHP integrated development environment

SAP NetWeaver Server Adapter for Eclipse
Integrate Eclipse with SAP NetWeaver application server.

DVWA
Damn Vulnerable Web App (DVWA) is a PHP/MySQL web application that is very vulnerable. Its main goals are to be an aid for security professionals to test their skills and tools in a legal environment, to help web developers better understand the process of securing web applications, and to help teachers/students teach/learn in a classroom environment Web application security. The goal of DVWA is to practice some of the most common web vulnerabilities through a simple and straightforward interface, with varying degrees of difficulty. Please note that this software