What is the potential pitfall of using the parent class to reference its child class in object-oriented programming?

The potential pitfall of using the parent class to reference its child class is that it can lead to tight coupling between the parent and child classes, making the code harder to maintain and extend. To solve this issue, it is recommended to use interfaces or abstract classes to define a contract that the child classes must adhere to, allowing for more flexibility and decoupling in the code. 

interface ChildInterface {
    // Define methods that child classes must implement
    public function doSomething();
}

class ParentClass {
    public function someMethod(ChildInterface $child) {
        // Call the child class method through the interface
        $child->doSomething();
    }
}

class ChildClass implements ChildInterface {
    public function doSomething() {
        // Implement the method required by the interface
        echo "Doing something in ChildClass";
    }
}

$parent = new ParentClass();
$child = new ChildClass();
$parent->someMethod($child);

Keywords

PHP object-oriented programming parent class child class inheritance

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