Access the parent object of an object in PHP - php

Question

This is my test code:
class Base
{
public $property;
public function method() {
return 456;
}
public function setProperty($value) {
$this->property = $value;
}
}
class Derived extends Base
{
public function method() {
return 789;
}
}
$derived = new Derived;
$derived->setProperty(123);
$base = getParentInstance($derived);
echo $base->property; // Should print 123
echo $base->method(); // Should print 456
Looking around I found a lot of stuff related but nothing direct to the point. I just need to cast an instance to an ancestor class. Is this even possible on PHP?
Up to now I came out with this wrong code that (I think) just instantiate a new Base class:
function getParentInstance($object)
{
$reflection = new ReflectionObject($object);
$parent_class = $reflection->getParentClass();
return $parent_class->newInstanceWithoutConstructor();
}
Another complication is I can only modify Derived... Base is provided by an external framework.
Addendum
Here is the proof what I'm requesting is not absurd. Same code in C++:
class Base
{
public:
int property;
int method() {
return 456;
}
void setProperty(int value) {
this->property = value;
}
};
class Derived: public Base
{
public:
int method() {
return 789;
}
};
#include <iostream>
int main()
{
Derived *derived = new Derived;
derived->setProperty(123);
Base *base = (Base *) derived; // Is **this** possible in PHP?
std::cout << base->property; // It prints 123
std::cout << base->method(); // It prints 456
return 0;
}

Answer 1

As many mentioned, you shouldn't do it, and technically speaking you can't.
You can simulate the behaviour to get the results you expect as following:
class Derived extends Base
{
protected $isProxy = false;
public function method() {
return $this->isProxy ? parent::method() : 'def';
}
/**
* not really a parent. The same class, which behave like a parent in this specific case
*/
public function getParent()
{
$this->isProxy = true;
$base = clone $this;
$this->isProxy = false;
return $base;
}
}
$derived = new Derived;
$derived->setProperty(123);
$base = $derived->getParent();
echo $base->property; // prints 123
echo $base->method(); // prints 456
EDIT:
a simplified example of what else you can do:
function getParentInstance($child) {
$base = new Base();
$base->property = $child->property;
return $base;
}
This works with public properties only.
Private/Protected properties should be accessed/assigned using Reflection.

Answer 2

Just figured I would put this here since it sort of answers the question. While there is not an instantiated Base object you still have access to parent data through php's parent.
I am not 100% sure what the attempt here is but you could use it like
//No changes to Base
class Derived extends Base {
public function method($p=false) {//Adding a flag
if($p){// true mean you want the parent method
return parent::method(); //Use parent:: to call that method
} else { //False do your own thing
return 'def';
}
}
}
$derived = new Derived;
$derived->setProperty(123);
echo $derived->property; // Print 123
echo $derived->method(); // Prints def
echo $derived->method(false); // Prints def
echo $derived->method(true); // Prints 456
This is strange but one way to at least get the expectations.
Also, the easiest way is to not overwrite your parent method when parent and child function differently.
//No changes to Base
class Derived extends Base {
public function child_method() {
return 'def';
}
}
$derived = new Derived;
$derived->setProperty(123);
echo $derived->property; // Print 123
echo $derived->method(); // Prints 456
echo $derived->child_method(false); // Prints def