Summary of basic usage examples of traits in php

To put it simply, the trait keyword is used in PHP to solve the problem that a class wants to integrate the attributes and methods of a base class, but also wants to have other base classes. method, and trait is generally used in conjunction with use.

carName}\n";
    }
  }
  class Person {
    public function eat() {
      echo "eat\n";
    }
  }
  class Student extends Person {
    use Drive;
    public function study() {
      echo "study\n";
    }
  }
  $student = new Student();
  $student->study();
  $student->eat();
  $student->driving();

?>

The output results are as follows:

study
eat
driving trait

In the above example, the Student class inherits Person through , has the eat method, and through the combination of Drive, there is driving Methods and properties carName.

If there is a property or method with the same name in Trait, base class and this class, which one will be retained in the end?

hello();
  $student->driving();
?>

The output results are as follows:

hello student
driving from drive

So we can conclude that when a method or attribute has the same name, the method in the current class will override the trait's method, and the trait's method will override the base class. method in.

If you want to combine multiple Traits, separate the Trait names by commas:

use Trait1, Trait2;

What happens if multiple Traits contain methods or properties with the same name? The answer is that when multiple combined Traits contain properties or methods with the same name, they need to be explicitly declared to resolve conflicts, otherwise a fatal error will occur.

The output results are as follows:

The code is as follows:

PHP Fatal error:  Trait method hello has not been applied, because there are collisions with other trait methods on Class1 in ~/php54/trait_3.php on line 20

Use insteadof and asoperators to resolve conflicts, insteadof is to use a method instead Another one, and as is to give an alias to the method. Please see the code for specific usage:

hello();
$Obj1->hi();
echo "\n";
$Obj2 = new Class2();
$Obj2->hello();
$Obj2->hi();
$Obj2->hei();
$Obj2->hehe();
?>

The output result is as follows:

Trait2::hello
Trait1::hi

Trait2::hello
Trait1::hi
Trait2::hi
Trait1::hello

The as keyword has another use, which is to modify the method. Access Control:

Trait can also be combined with Trait. Trait supports abstract methods, static properties and static methods. The test code is as follows:

sayHello();
$Obj->sayWorld();
echo $Obj->getWorld() . "\n";
HelloWorld::doSomething();
$Obj->inc();
$Obj->inc();
?>

The output is as follows:

Hello
World
get World
Doing something
1
2

The above is the detailed content of Summary of basic usage examples of traits in php. For more information, please follow other related articles on the PHP Chinese website!