Determine if a variable only belongs to a child class in PHP

Question

I have a parent class and a child class. Through a function in the parent class, I am looping through the members of the class and setting values for each of them. However, when I iterate through the class members, I do so for ALL members (those of the parent and child class) like so:

In Parent Class:

foreach($this as $member_name => $member_value) {
 if(property_exists(get_class($this),$member_name) && isset($member_value))
     //do something....
}//end foreach

However, the above code is is treating PARENT class member variables as properties of the child class. Member variables in parent class are declared protected and I cannot change that so I understand why this is happening. I cannot declare members of parent class private (which would have solved my problem)!

My question: Is there a way to determine is a member variable belongs to a child class and child class ONLY from within the parent class without declaring all parent member variables private?

Answer 1

One solution to this could be using reflection to get info about properties.

<?php

class A {
  protected $a = 1;
  protected $b = 2;

  public function aa() {
    echo 'called class: '.get_class($this).PHP_EOL;

    $r = new ReflectionClass($this);
    $properties = [];
    foreach($r->getProperties() as $property) {
      $properties[$property->name] = $property->class;
    }

    echo 'properties info:'.PHP_EOL;
    var_dump($properties);

    echo 'iterate properties:'.PHP_EOL;
    foreach ($this as $k => $v) {
      echo $k.' => '.$v.', in: '.$properties[$k].', own: '.($properties[$k] === __CLASS__ ? 'yes': 'no').PHP_EOL;
    }
  }
}

class B extends A {
  protected $c = 3;
}

$a = new A();
$a->aa();
$b = new B();
$b->aa();

Output:

called class: A
properties info:
array(2) {
  ["a"]=>
  string(1) "A"
  ["b"]=>
  string(1) "A"
}
iterate properties:
a => 1, in: A, own: yes
b => 2, in: A, own: yes
called class: B
properties info:
array(3) {
  ["c"]=>
  string(1) "B"
  ["a"]=>
  string(1) "A"
  ["b"]=>
  string(1) "A"
}
iterate properties:
c => 3, in: B, own: no
a => 1, in: A, own: yes
b => 2, in: A, own: yes

So in this example we test both parent $a and child $b and from parent method aa we always have information about who is the "owner" of the property.

Solution 2: Instead of aa method with reflection (if you dont need to know who is the owner, only if it is the parent property or not) try method bb:

public function bb() {
    echo 'called class: '.get_class($this).PHP_EOL;

    foreach ($this as $k => $v) {
      echo $k.' '.(property_exists(__CLASS__,$k) ? 'own' : 'not own').PHP_EOL;
    }
  }

So check if property exists on class level, output:

called class: A
a own
b own
called class: B
c not own
a own
b own

Answer 2

I know what you are asking about and here is the solution to "ignore" the parent class's members:

foreach($this as $member_name => $member_value) {
 if(property_exists(get_class($this),$member_name) && isset($member_value) && !property_exists(__CLASS__,$member_name))
     //do something....
}//end foreach

The third statement in the 'if' will filter out those members that belong to the parent class.