抽象类和实现

Question

I have a class which contains an abstract method, which is implemented in child class.

class A {
  public abstract function foo();
}

class B extends A {
  public function foo() {
      return true;
  }
}

How i can get B class's A function value in A class? The classes are in different files and class A already extends from a class

Answer 1

abstract class A {

    abstract public function foo();

    public function bar() {
        echo $this->foo();
    }

}

class B extends A {

    public function foo() {
        return true;
    }

}

$b = new B;
$b->bar();