Circular references: dereferencing method

dereferencing-method.php

<?php

class ParentClass
{
    public function __construct()
    {
        $this->child = new ChildClass($this);
    }

    public function destroy()
    {
        $this->child->destroy();
    }
}

class ChildClass
{
    public function __construct(ParentClass $parent)
    {
        $this->parent = $parent;
    }

    public function destroy()
    {
        // By setting the parent property to null, you remove the circular reference.
        $this->parent = null;
    }
}

$instance = new ParentClass;

// Do your work...

// Before unreferencing the parent, call the destroy method.
$instance->destroy();

// Unreference the parent
unset($instance);