Detailed explanation of Trait characteristics and functions in PHP with examples

Traits is a code reuse mechanism prepared for single inheritance languages ​​like PHP. Trait In order to reduce the restrictions of single inheritance language, developers can freely reuse method sets in independent classes within different hierarchies

Since PHP 5.4.0, PHP has implemented a method of code reuse , called traits.

Traits is a code reuse mechanism prepared for single inheritance languages ​​like PHP. Traits are designed to reduce the constraints of single-inheritance languages ​​and allow developers to freely reuse method sets in independent classes within different hierarchies. The semantics of traits and class composition define a way to reduce complexity and avoid the typical problems associated with traditional multiple inheritance and mixins.

Trait is similar to a class, but is only designed to combine functionality in a fine-grained and consistent way. Trait cannot be instantiated by itself. It adds a combination of horizontal features to traditional inheritance; that is, members of application classes do not need to be inherited.

Trait was added in PHP5.4. It is neither an interface nor a class. Mainly to solve the limitations of single inheritance languages. It is a solution to multiple inheritance in PHP. For example, it would be very troublesome to inherit two Abstract Classes at the same time. Trait is designed to solve this problem. It can be added to one or more existing classes. It declares what the class can do (indicating its interface characteristics), and also contains the specific implementation (indicating its class characteristics)

Simple use

First, Of course, declare a Trait. PHP5.4 added the trait keyword

trait first_trait {
function first_method() { /* Code Here */ }
function second_method() { /* Code Here */ }
}

At the same time, if you want to use the Trait in Class, use the use keyword

class first_class {
// 注意这行，声明使用 first_trait
use first_trait;
}
$obj = new first_class();
// Executing the method from trait
$obj->first_method(); // valid
$obj->second_method(); // valid

Use multiple Traits

trait first_trait
{
function first_method() { echo "method"; }
}
trait second_trait {
function second_method() { echo "method"; }
}
class first_class {
// now using more than one trait
use first_trait, second_trait;
}
$obj= new first_class();
// Valid
$obj->first_method(); // Print : method
// Valid
$obj->second_method(); // Print : method

Nesting between Traits

trait first_trait {
function first_method() { echo "method"; }
}
trait second_trait {
use first_trait;
function second_method() { echo "method"; }
}
class first_class {
// now using 
use second_trait;
}
$obj= new first_class();
// Valid
$obj->first_method(); // Print : method
// Valid
$obj->second_method(); // Print : method

Abstract Method of Trait

trait first_trait {
function first_method() { echo "method"; }
// 这里可以加入修饰符，说明调用类必须实现它
abstract public function second_method();
}
class first_method {
use first_trait;
function second_method() {
/* Code Here */
}
}

Trait conflict

trait first_trait {
function first_function() { 
echo "From First Trait";
}
}
trait second_trait {
// 这里的名称和 first_trait 一样，会有冲突
function first_function() { 
echo "From Second Trait";
}
}
class first_class {
use first_trait, second_trait {
// 在这里声明使用 first_trait 的 first_function 替换
// second_trait 中声明的
first_trait::first_function insteadof second_trait;
}
} 
$obj = new first_class();
// Output: From First Trait
$obj->first_function();

:

Analysis of concepts and usage examples of abstract classes and abstract methods in PHP

Inheritance of classes in PHP Detailed explanation with usage examples

phpSeveral ways to obtain the physical path of the website root directory

The above is the detailed content of Detailed explanation of Trait characteristics and functions in PHP with examples. For more information, please follow other related articles on the PHP Chinese website!