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php的trait属性冲突

发布时间：2021-09-24 12:14:09编辑：雪饮阅读（）

 对于php的trait中属性冲突，像是trait中和基类和派生类中若存在属性冲突（同名属性）是会解析出错误的：

test.php：
<?php
trait Dog{
    public $name="dog";
    public function bark(){
        echo "This is dog";
    }
    public function eat(){
        echo "Dog:This is dog";
    }
}
class Animal{
    public $name="Animal";
    public function eat(){
        echo "This is animal eat";
    }
}
class Cat extends Animal{
    public $name="cat";
    use Dog;
    public function drive(){
        echo "This is cat drive";
    }
    public function bark(){
        echo "Cat:This is dog";
    }
}
$cat = new Cat();
$cat->drive();
echo "<br/>";
$cat->eat();
echo "<br/>";
$cat->bark();
?>
运行结果：
C:\Users\Administrator\PhpstormProjects\untitled\organizing>D:\phpstudy_pro\Extensions\php\php7.3.4nts\php.exe C:\Users\Administrator\PhpstormProjects\untitled\test.php
 
Fatal error: Cat and Dog define the same property ($name) in the composition of Cat. However, the definition differs and is considered incompatible. Class was composed in C:\Users\Administrator\PhpstormProjects\untitled\test.php on line 17
 
Call Stack:
0.0002     398760   1. {main}() C:\Users\Administrator\PhpstormProjects\untitled\test.php:0
但是如果冲突的属性的值都是相同的，且可见性也是相同的：test.php：

<?php
trait Dog{
    public $name="dog";
    public function bark(){
        echo "This is dog";
    }
    public function eat(){
        echo "Dog:This is dog";
    }
}
class Animal{
    public $name="dog";
    public function eat(){
        echo "This is animal eat";
    }
}
class Cat extends Animal{
    public $name="dog";
    use Dog;
    public function drive(){
        echo "This is cat drive";
    }
    public function bark(){
        echo "Cat:This is dog";
    }
}
$cat = new Cat();
$cat->drive();
echo "<br/>";
$cat->eat();
echo "<br/>";
$cat->bark();
?>

则又是可以运行成功的：

C:\Users\Administrator\PhpstormProjects\untitled\organizing>D:\phpstudy_pro\Extensions\php\php7.3.4nts\php.exe C:\Users\Administrator\PhpstormProjects\untitled\test.php
This is cat drive<br/>Dog:This is dog<br/>Cat:This is dog
但是据说在php7之前，会产生E_STRICT错误，我的理解就是declare(strict_types=1); 模式下，也就是说严格模式下，但是这个模式不是php7才出现的新特性吗？