Traits
Many of my PHP developer friends don’t know much about traits, which is a new concept introduced in PHP 5.4.0. Traits look like interfaces but work like classes, so what exactly are they? It's neither.
A trait has partial implementation (such as constants, properties and methods) that can be embedded into one or more actual PHP classes. Traits have two responsibilities: indicating what a class can do (similar to an interface); and providing a modular implementation (similar to a class).
You may already have some understanding of traits in other languages. For example, the functions of Ruby's modules and mixins are very similar to PHP's traits.
Why should we use traits
PHP language uses the classic inheritance model. This means that you start with a common root class that provides the basic implementation. From the root class, more specific classes are created that directly inherit the various implementations of the parent class. This is called an inheritance hierarchy, and many programming languages use this common pattern.
To make it easier to understand, imagine that you travel back in time to high school to study biology. Do you still remember the phylum, order, family, genus and species of the organisms you studied? There are six major realms in total. The realm is derived from the door, the phylum is derived from the class, the class is derived from the order, the order is derived from the family, the family is derived from the genus, and the genus is followed by the species. Each descent down the species hierarchy represents a specific characteristic.
The classic inheritance model works well in most cases. But what if there are two unrelated classes that need to implement similar behavior? For example, one PHP class is called RetailStore, and another PHP class is called Car. They can be said to be two completely unrelated classes, and they cannot share a common parent class in terms of inheritance relationship. However, both classes require the longitude and latitude from the geographic location to display map coordinates.
We created traits to solve this problem. They can inject partial implementation into unrelated classes. Traits also facilitate code reuse.
When I encounter this problem, my first solution (and the worst) is to create a public parent class Geocodable for the RetailStore and Car classes to inherit. This solution is really bad, because forcing two unrelated classes to share a common ancestor looks very awkward in their respective inheritance hierarchies.
My second solution (slightly better) is to create a Geocodable interface that defines what methods are needed to implement geolocation. Both RetialStore and Car classes can implement this Geocodable interface. It is indeed a good solution to allow each class to retain its natural inheritance relationship. But we still need to repeat the definition in the interface in each class, which is not a DRY solution.
DRY is the abbreviation of Do not repeat yourself. As a good programming practice, we should never repeat the same code in multiple places. There cannot be a situation where you have to passively modify the same code in other places because you have changed one piece of code.
My third solution (the best solution) is to construct a Geocodable trait and define and implement related methods in it. I can add Geocodable traits to the RetailStore class and Car class without disrupting the class inheritance hierarchy.
How to construct a trait
The following shows how to define a PHP trait:
<?php trait MyTrait { // 此处是trait的具体实现 }
As a good habit, we should do one trait per file, just like the definition of classes and interfaces .
Let’s go back to our Geocodable example to better demonstrate the use of traits. We all know that the RetailStore class and the Car class need to support the geographical positioning function, and we can all agree that inheritance and interfaces are not the best solution. Instead, we construct a Geocodable trait that returns a longitude and latitude coordinate that can be marked on the map. Example 2-12 shows our complete Geocodable trait.
Example 2-12 Definition of Geocodable trait
<span style="font-size:14px;"><?php trait Geocodable { /** @var string */ protected $address; /** @var \Geocoder\Geocoder */ protected $geocoder; /** @var \Geocoder\Result\Geocoded */ protected $geocoderResult; public function setGeocoder(\Geocoder\GeocoderInterface $geocoder) { $this->geocoder = $geocoder; } public function setAddress($address) { $this->address = $address; } public function getLatitude() { if (isset($this->geocoderResult) === false) { $this->geocodeAddress(); } return $this->geocoderResult->getLatitude(); } public function getLongitude() { if (isset($this->geocoderResult) === false) { $this->geocodeAddress(); } return $this->geocoderResult->getLongitude(); } protected function geocodeAddress() { $this->geocoderResult = $this->geocoder->geocode($this->address); return true; } }</span>
Geocodable trait only defines the properties and methods required to implement the geographical location function without any additional functions.
Our Geocodable trait defines properties of three classes:
To be continued...
The above introduces [Modern PHP] Chapter 2 New Features Three Traits, including aspects of the content. I hope it will be helpful to friends who are interested in PHP tutorials.

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.

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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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