php – 与其他特征方法的冲突

发布时间：2020-12-13 13:40:03 所属栏目：PHP教程来源：网络整理

导读：如何用同名方法处理特征？ trait FooTrait { public function fooMethod() { return 'foo method'; } public function getRow() { return 'foo row'; }}trait TooTrait { public function tooMethod() { return 'too method'; } public function getRow() {

如何用同名方法处理特征？

trait FooTrait {
  public function fooMethod() {
        return 'foo method';
  }

  public function getRow() {
        return 'foo row';
  }
}

trait TooTrait {
    public function tooMethod() {
        return 'too method';
    }

    public function getRow() {
        return 'too row';
    }
}

class Boo
{
    use FooTrait;
    use TooTrait;

    public function booMethod() {
        return $this->fooMethod();
    }
}

错误,

Fatal error: Trait method getRow has not been applied,because there
are collisions with other trait methods on Boo in…

我该怎么办？

而且,使用两个相同的方法名称,如何从trait FooTrait获取该方法？

$a = new Boo;
var_dump($a->getRow()); // Fatal error: Call to undefined method Boo::getRow() in...

编辑：

class Boo
{
    use FooTrait,TooTrait {
        FooTrait::getRow insteadof TooTrait;
    }

    public function booMethod() {
        return $this->fooMethod();
    }
}

如果我想通过Boo从TooTrait获取getRow的方法呢？可能吗？

PHP关于冲突的文档：

If two Traits insert a method with the same name,a fatal error is
produced,if the conflict is not explicitly resolved.

To resolve naming conflicts between Traits used in the same class,the
insteadof operator needs to be used to chose exactly one of the
conflicting methods.

Since this only allows one to exclude methods,the as operator can be
used to allow the inclusion of one of the conflicting methods under
another name.

Example #5 Conflict Resolution

In this example,Talker uses the traits A and B. Since A and B have
conflicting methods,it defines to use the variant of smallTalk from
trait B,and the variant of bigTalk from trait A.

The Aliased_Talker makes use of the as operator to be able to use B’s
bigTalk implementation under an additional alias talk.

<?php trait A {
     public function smallTalk() {
         echo 'a';
     }
     public function bigTalk() {
         echo 'A';
     } }

 trait B {
     public function smallTalk() {
         echo 'b';
     }
     public function bigTalk() {
         echo 'B';
     } }

 class Talker {
     use A,B {
         B::smallTalk insteadof A;
         A::bigTalk insteadof B;
     } }

 class Aliased_Talker {
     use A,B {
         B::smallTalk insteadof A;
         A::bigTalk insteadof B;
         B::bigTalk as talk;
     } }

所以在你的情况下可能是

class Boo
{
    use FooTrait,TooTrait {
        FooTrait::getRow insteadof TooTrait;
    }

    public function booMethod() {
        return $this->fooMethod();
    }
}

(即使你单独使用也可以工作,但我认为更清楚)

或者使用as来声明一个别名.

（编辑：李大同）

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