Introduction to trait syntax for implementing multiple inheritance in PHP (code example)

This article brings you an introduction to the trait syntax (code example) for implementing multiple inheritance in PHP. It has certain reference value. Friends in need can refer to it. I hope it will help You helped.

PHP does not have multiple inheritance features. Even in a programming language that supports multiple inheritance, we rarely use this feature. In most people's opinion, multiple inheritance is not a good design method.

But what should we do if we use multiple inheritance in development?
The following introduces the problem of using "trait" to implement multiple inheritance in php.

Since PHP5.4, PHP has implemented the "trait" syntax for code reuse.

Trait is a code reuse mechanism prepared for PHP's single inheritance language. In order to reduce the limitations of single inheritance, methods are developed to reuse methods at different structural levels. The semantics of the combination of
Trait and Class define a way to reduce complexity and avoid typical problems related to traditional multiple inheritance and Mixin classes.

It should be noted that members inherited from the base class will be overwritten by members inserted by the trait. The order of precedence is that members from the current class override the trait's methods, and the trait overrides the inherited methods.

Let’s take an example first:

trait TestOne{
    public function test()
    {
        echo "This is trait one <br/>";
    }
}
trait TestTwo{
    public function test()
    {
        echo "This is trait two <br/>";
    }
    public function testTwoDemo()
    {
        echo "This is trait two_1";
    }
}
class BasicTest{
    public function test(){
        echo "hello world\n";
    }
}
class MyCode extends BasicTest{
    //如果单纯的直接引入，两个类中出现相同的方法php会报出错
    //Trait method test has not been applied, because there are collisions with other trait
    //methods on MyCode
    //use TestOne,TestTwo;
    //怎么处理上面所出现的错误呢，我们只需使用insteadof关键字来解决方法的冲突
    use TestOne,TestTwo{
        TestTwo::test insteadof TestOne;
    }
}
$test = new MyCode();
$test->test();
$test->testTwoDemo();

Running result:

This is trait two
This is trait two_1

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