trait与接口/抽象类实战

//命名冲突和改变访问控制

     trait t8{

         public function say(){

              echo 'these are two method with the same name.';

         }

     }

     trait t9{

         protected function say(){

            echo 'these are two method with the same name.';

         }

     }

     trait t10{

         use t8,t9{

             t8::say insteadof t9;

             t9::say as public read;

         }

     }

     class work3{

        use t10;

     }

     $work3=new work3();

     echo $work3->say().'<br>';

     echo $work3->read().'<br>';

//trait和interface及class

     trait t11{

         public function aa($year){

             $age=2020-$year;

             return $age;

         }

     }

    

     interface i2{

         const NAME='jack';

         public function caculator(int $i);

     }

    

     class Work4 implements i2{

         use t11;

         public function caculator(int $i){

             if($i>0){

                 $sum=0;

                 for($j=0;$j<=$i;$j++){

                      $sum=$sum+$j;

                 }

                 return $sum;

              }else {

                  return '参数非法';

              }

          }

     }

     $work4=new Work4();

     echo '参数年份，计算年龄：<br>';

     echo $work4::NAME.'的年龄是：'.$work4->aa(2000).'<br>';

     echo '参数正整数，进行累加：<br>';

     echo '结果是'.$work4->caculator(10).'<br>';

    

    //trait的理解：一些方法和常量打包在trait里面，在类中使用时，use一下就能用，

    //优点：省去了父类/子类和继承，以及访问控制这些麻烦（trait中都是public);

    //缺点：a.方法都是public，不能访问限制；b.由于trait可以use trait，层数多了可能会把我搞晕吧！