


Learn design patterns with me (2), learn design patterns_PHP tutorial
Learn design patterns with me (2), learn design patterns
The factory pattern is very important in polymorphic design. If applied properly, it can make the application The portability is better, and the dependencies between classes are looser, thereby improving flexibility. If the singleton pattern is considered the responsibility of the class, then the factory pattern is the polymorphism of the class.
So what is a factory class?
Concept: A factory class refers to a class that contains a method specifically used to create other objects.
Application scenario: Factory pattern is usually used to return different classes that conform to similar interfaces. In other words, factory classes allow us to decide which class to instantiate based on configuration or application logic.
The following is a simple factory class code:
<span><span>interface</span><span> IDatabase { //...</span><span>public</span> <span>function</span> query(<span>$sql</span><span>);</span><span> } </span><span>class</span><span> DBFactory { </span><span>public</span> <span>static</span> <span>function</span> create(<span>$type</span><span>){ </span><span>$db</span> = <span>null</span><span>; </span><span>switch</span> (<span>$type</span><span>) { </span><span>case</span> 'mysql': <span>$db</span> = <span>new</span> <span>Mysql</span>(<span>/*</span><span>*arguments</span><span>*/</span><span>); </span><span>break</span><span>; </span><span>case</span> 'sqlite': <span>$db</span> = <span>new</span> Sqlite(<span>/*</span><span>*arguments</span><span>*/</span><span>); </span><span>break</span><span>; </span><span>case</span> 'pgsql': <span>$db</span> = <span>new</span> PGsql(<span>/*</span><span>*arguments</span><span>*/</span><span>); </span><span>break</span><span>; </span><span>default</span>: <span>#</span><span> code...</span> <span>break</span><span>; } </span><span>return</span> <span>$db</span><span>; } } </span><span>class</span> <span>Mysql</span> <span>implements</span><span> IDatabase { </span><span>//... </span><span>public</span> <span>function</span> query(<span>$sql</span><span>){ }</span><span> } </span><span>/*</span><span>*other class ...</span><span>*/</span></span>
Use factory class:
<span><span>$db</span> = DBFactory::create('mysql'<span>); </span><span>$db</span>->query('show database');</span>
Every database here inherits the specified interface. The purpose of this is to make all database objects have consistent external performance. External classes can safely use the methods declared in the interface, which is what we often call transparent to users in software engineering. If one day, due to changes in the computer room, we want to switch to another database, we only need to implement the relevant database classes according to the interface, and the business code does not need to be changed. This reflects the flexibility and polymorphism of the factory class.
From another perspective, we concentrated all the changes at the entrance. There is no need to perform repeated if-else processing internally for these changes.
Okay, there is only so much theoretical content. More experience needs to be applied in projects and to appreciate its benefits.

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.


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