Question

我一步一步跟随this video，但我似乎确实在某个地方犯了错误。任何人都可以解释我的错误在哪里以及如何解决它？

的index.php

<?php
require 'Classes/Calculator.php';
require 'Classes/OperatorInterface.php';
require 'Classes/Adder.php';
require 'Classes/Subtractor.php';

$c = new Calculator;

$c->setOperation(new Adder);
$c->calculate(10, 50);

echo $c->getResult();
?>

Calculator.php中

<?php
class Calculator{

    protected $result;

    protected $operation;

    public function setOperation(OperatorInterface $operation){
        $this->operation = $operation;
    }

    public function calculate(){
        foreach(func_get_args() as $number){
            $this->result = $this->operation->run($number, $this->$result);
        }
    }

    public function getResult(){
        return $this->result;
    }
}
?>

Adder.php

<?php
class Adder implements OperatorInterface{
    public function run($number, $result){
        return $result + $number;
    }
}
?>

OperatorInterface.php

<?php
interface OperatorInterface{
    public function run($number, $result);
}
?>

我刚刚开始学习OOP，所以这可能是一个非常愚蠢的错误，提前抱歉...感谢您的帮助！

Answer 1

Calculator::calculate()中有一个拼写错误，$this->$result应为$this->result：

public function calculate(){
    foreach(func_get_args() as $number){
        $this->result = $this->operation->run($number, $this->result);
    }
}

在引用班级的成员变量（属性）时，$之后不需要->。

致命错误：无法访问空属性，为什么它是空的？

1 个答案: