Tag: objects

Convert a PHP object to an associative array

// start
class MyClass {

	public $var1 = 1;
	public $var2 = 2;
	public static $var3 = 3;
	protected $var4 = 4;
	private $var5 = 5;
	
	public function toArray() {
		return (array) get_object_vars($this);
	}
} 

function toArray($object) {
	//$reflectionClass = new ReflectionClass(get_class($object));
	$reflectionClass = new ReflectionObject($object);
    $array = [];
    foreach ($reflectionClass->getProperties() as $property) {
        $property->setAccessible(true);
        $array[$property->getName()] = $property->getValue($object);
        $property->setAccessible(false);
    }
    return $array;
}

$object = new MyClass(); 
$array = toArray($object);
$array2 = $object->toArray();
print_r($array2);	// Inaccessible NO static
print_r($array);	// Inaccessible and static

$obArray = [];
foreach($object as $ob){
	$obArray[] = $ob;
}
print_r($obArray);	// public only


Array
(
    [var1] => 1
    [var2] => 2
    [var4] => 4
    [var5] => 5
)
Array
(
    [var1] => 1
    [var2] => 2
    [var3] => 3
    [var4] => 4
    [var5] => 5
)
Array
(
    [0] => 1
    [1] => 2
)

Merging PHP Objects

Given two objects of same class, merge both objects into a single object.


class MyClass {} 
  
$objectA = new MyClass(); 
$objectA->a = 1; 
$objectA->b = 2; 
$objectA->d = 3; 
  
$objectB = new MyClass(); 
$objectB->d = 4; 
$objectB->e = 5; 
$objectB->f = 6; 
 
// Using array_merge
$obj_merged = (object) array_merge((array) $objectA, (array) $objectB); 
print_r($obj_merged);
stdClass Object
(
    [a] => 1
    [b] => 2
    [d] => 4
    [e] => 5
    [f] => 6
)

// Using array union operator
$obj_union = (object)((array) $objectA +(array) $objectB);        
print_r($obj_union);
stdClass Object
(
    [a] => 1
    [b] => 2
    [d] => 3
    [e] => 5
    [f] => 6
)

PHP: self vs $this

Self:
-self refers to the current class
-self can be used to call static functions and reference static member variables
-self can be used inside static functions
-self can also turn off polymorphic behavior by bypassing the vtable

$this:
-$this refers to the current object
-$this can be used to call object functions
-$this should not be used to call static member variables. Use self instead.
-$this can not be used inside static functions

self = Current class.
static = Current class in runtime.
parent = Parent class. 

class Test
{
    private $baz = 1;

	public static function foo() 
    { 
        echo "foo\n"; 
    }

  	public function bar()
  	{
    	echo "bar\n";
	    $this->foo();
    	$this::foo();
	    self::foo();
        self::baz();
  	}

	public function baz()
    {
        printf("baz = %d\n", $this->baz);
    }
}

$test = new Test;
$test->bar(); // bar foo foo foo baz = 1


PHP manual
Declaring class properties or methods as static makes them accessible without needing an instantiation of the class. A property declared as static can not be accessed with an instantiated class object (though a static method can).

Test::foo(); // foo

Is the same as

$test->foo(); // foo

Track number of objects created from a class

To track the existing number of objects of a given class create a static property to hold the current value, updated with the constructor. When unsetting an object, the __destruct() method will update the object count. You can create new instances without hitting the constructor via clone and deleted with unset()


/*
* Class TrackableClass 
*/
class TrackableClass {
    public static $instances = 0;

    public function __construct() 
    {
        self::$instances++;
    }

    public function __destruct() 
    {
        self::$instances--;
    }
	
    public function __clone() 
    {
	self::$instances++;
    }
	
    public function __unset($name)
    {
        self::$instances--;
    }
	
}

$obj1 = new TrackableClass();
$obj2 = new TrackableClass();
$obj3 = new TrackableClass();
$obj4 = clone $obj3;

echo TrackableClass::$instances; // 4
unset($obj4);
echo TrackableClass::$instances; // 3
$obj3 = null;
echo TrackableClass::$instances; // 2

PHP Method Chaining

Method chaining, also known as named parameter idiom, is a common syntax for invoking multiple method calls in object-oriented programming languages. Each method returns an object, allowing the calls to be chained together in a single statement without requiring variables to store the intermediate results


/*
* ChainableClass
* cascading-by-chaining by returning this
*/
class ChainableClass {
  function methodOne() {
    echo __METHOD__.' called, ';
    return $this;
  }
  function methodTwo() {
    echo __METHOD__.' called';
    return $this;
  }
}
(new ChainableClass)->methodOne()->methodTwo();
// Result: BaseClass::methodOne called, BaseClass::methodTwo called

With Static


/*
* ChainableClass
* cascading-by-chaining by returning self
*/
class ChainableClassStatic {
  public static $prop;

  public static function ChainableStaticMethod()
  {
    self::$prop = 'Chainable Class String';
    return new self;
  }

  public function regularMethod()
  {
    echo self::$prop;
  }
}
ChainableClassStatic::ChainableStaticMethod()->regularMethod();
// Result: Chainable Class String