实例讲解一下：依赖注入的实现原理(构造器与普通方法)

//依赖注入 Dependency_injection

class Calculator
{
   public function calculate()
   {
       return '计算结果';
   }
}
$calculator = new Calculator();

//构造方法注入
class Person
{
   protected $calculator = null;
   public function __construct(Calculator $calculator)
   {
       $this->calculator = $calculator;
   }

   public function operate()
   {
       return $this->calculator->calculate();
   }
}
$person1 = new Person($calculator);
echo $person1->operate();
 
//操作方法注入
class People
{
   public function operating(Calculator $calculator)
   {
       return $calculator->calculate();
   }
}
$people = new People();
echo $people->operating($calculator);