PHP中带有变量参数列表的抽象方法

Question

I came across a question in OOP in PHP. I tried to implement an abstract parent class method and from the child class, I have to use it with a variable number of arguments.

Here is the error thrown :

PHP Fatal error: Declaration of Square::getArea($length) must be compatible with Shape::getArea()

And the classes :

abstract class Shape {
    abstract protected function getArea();
}

class Square extends Shape {

    public function getArea($length)
    {
        return pow($length, 2);
    }

}

class Triangle extends Shape {

    public function getArea($base, $height)
    {
        return .5 * $base * $height;
    }

}

I could use the child's __construct() methods to set the properties of the different shapes at the initiation time but I'd like to know if another way exists and allows me to define variable list of parameters.

Thanks in advance.

Answer 1

As in the comments under your question mentioned, there are several ways to solve your issue.

Class properties and the constructor That would be the easiest approach in my opinion. It 's easy and smart.

interface Shape
{
    protected function getShape();
}

class Square implements Shape
{
    protected $length;

    public function __construct(int $length)
    {
        $this->length = $length;
    }

    protected function shape()
    {
        return pow($this->length, 2);
    }
}

class Triangle implements Shape
{
    protected $base;

    protected $height;

    public function __construct(int $base, int $height)
    {
        $this->base = $base;
        $this->height = $height;
    }

    protected function getShape()
    {
        return .5 * $this->base * $this->height;
    }
}

Every class implements the Shape interface. The getShape method got no attributes. The attributes are protected properties of the class itself. You set these properties when calling the constructor of the specific class.