How to access parent class from child class? - php

Question

I'm trying to automate a form validation and db insertion process. In a particular part, I need to be able to access the parent class from the child class. To be exact, I need to access the parent class to access another child class.
I've tried to replicate the same structure I'm using in the actual code:
class Family {
public function __construct($members = []) {
foreach ($members as $member) {
$this->$member[0] = new Member($member);
}
}
}
class Member {
public $name;
public $niisan;
public function __construct($name = []) {
$this->name = $name[0];
if (count($name) > 1) {
$this->get_niisan($name[1]);
}
}
public function get_niisan($member_lookup) {
$this->niisan = $this->name . " has a niisan named X";
}
}
$Winchesters = new Family([
["Dean"],
["Sam", "Dean"],
]);
Output:
object(Family)#1 (2) {
["Dean"] => object(Member)#2 (2) {
["name"] => "Dean"
["niisan"] => NULL
}
["Sam"] => object(Member)#3 (2) {
["name"] => "Sam"
["niisan"] => "Sam has a niisan named X"
}
}
What I want to do is create two subclasses in the main class. Order of the creation of subclasses matters. ["Sam"] is dependant on ["Dean"], so ["Dean"] needs to be created first. Some of the properties of ["Dean"] will be used in ["Sam"].
In JavaScript, I'd write it like this:
function Family(members) {
var parent = this; // Family object
for (var i = 0; i < members.length; i++) {
// passing a reference of Family to the new Member object
// so that it can access the main object later
this[members[i][0]] = new Member(parent, members[i]);
}
}
function Member(parent, name) {
// saving the reference to the parent object
this.parent = parent;
this.name = name[0];
this.niisan = "";
this.get_niisan = function (lookup) {
// accessing the parent object and then getting the name property of "Dean" object
this.niisan = this.name + " has a niisan named " + this.parent[lookup].name;
};
if (name.length > 1) {
this.get_niisan(name[1]);
}
}
var Winchesters = new Family([
["Dean"],
["Sam", "Dean"]
]);
Passing the main object to each sub-object. PHP must have its own way to deal with this. I just don't know it.
Update: For the down/close-voter: How is this unclear?
I have two classes: Family and Member. Member class is initialized inside the Family class. Following code
$Winchesters = new Family([
["Dean"],
["Sam", "Dean"],
]);
results in:
object(Family)#1 (2) {
["Dean"] => object(Member)#2 (2) {
["name"] => "Dean"
["niisan"] => NULL
}
["Sam"] => object(Member)#3 (2) {
["name"] => "Sam"
["niisan"] => "Sam has a niisan named X"
}
}
At runtime, first a Member with the name "Dean" is created and assigned to a variable Dean inside Family.
Second, Member "Sam" is created, but Sam is dependant on the first created object, Dean. Sam needs to access the parent class Family, and then access to Dean, and get the property name and use it in assigning niisan variable.
Please check the JavaScript example. I want to mimic the exact functionality in PHP. Pass the main class to the child class so that the child class can access the later-created variables inside the main class.

Answer 1

In a particular part, I need to be able to access the parent class
from the child class. To be exact, I need to access the parent class
to access another child class.
You can't access another child class from a parent class. Only the child can access the parent. In your example, you haven't created any kind of inheritance. This is how you create inheritance in PHP.
class FooParent {
public function display($text) {
echo $text;
}
}
class Foo extends FooParent {
public function someMethod() {
// ask the parent to display the text
parent::display("Hello World!");
}
}
$foo = new Foo();
$foo->someMethod();
Which would display "Hello World!". Hopefully this will help you get started, to learn more about PHP's version of OOP - http://php.net/manual/en/language.oop5.php

Answer 2

Your terminology is confusing. In PHP OOP, parent and child usually refer to relationships between classes that inherit from each other, not the objects of those classes (C++ calls them base and derived class, and Javascript uses prototype chains for parent classes).
What you need to do is store a reference to the Family in the Member class.
class Member {
public $name;
public $niisan;
public $family;
public function __construct($name = [], $family) {
$this->family = $family;
$this->name = $name[0];
if (count($name) > 1) {
$this->get_niisan($name[1]);
}
}
public function get_niisan($member_lookup) {
$this->niisan = $this->name . " has a niisan named X";
}
}
class Family {
public function __construct($members = []) {
foreach ($members as $member) {
$this->$member[0] = new Member($member, $this);
}
}
}
Then if the Member class wants to access siblings, it can use $this->family to get the containing family.
BTW, using variable-named properties in Family is poor design, IMHO. Instead, you should use a single $member property containing an associative array:
$this->members = array();
foreach ($members as $member) {
$this->members[$member[0]] = new Member($member, $this);
}