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Lazy-loading for PHP
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<?php | |
class Address { | |
public $street; | |
public $town; | |
} | |
class Customer { | |
public $id; | |
public $name; | |
public $address; | |
} | |
class Payment { | |
public $amount; | |
public $customer; | |
} | |
$db = getDatabase(); | |
$payment = $db->load('Payment', 123); | |
/* | |
$payment containts: | |
amount = 100; | |
customer = class Customer { | |
id = 5; | |
name = uninitialized; | |
address = uninitialized; | |
} | |
} | |
*/ | |
echo $payment->customer->name; // DB layer will load customer info | |
// or | |
echo $payment->customer->address->town; // DB layer will load customer & address info | |
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<?php | |
/** | |
* Example of possible lazy-loading in PHP | |
* Added new special value called "uninitialized". When a property with this value is being read from object, | |
* __initialize($propertyName) magic method is invoked to lazy-load the value. | |
*/ | |
class Foo { | |
private $bar = uninitialized; | |
private $lol = "lol"; | |
public $pub = uninitialized; | |
public $blank = uninitialized; | |
function getBar() { | |
echo "Getter method bar, "; | |
return $this->bar; | |
} | |
function getLol() { | |
echo "Getter method lol, "; | |
return $this->lol; | |
} | |
function getPub() { | |
echo "Getter method pub, "; | |
return $this->pub; | |
} | |
function __get($name) { | |
echo "Magic getter $name, "; | |
return $this->$name; | |
} | |
function __initialize($name) { | |
if($name !== 'blank') { | |
echo "Initializing $name, "; | |
$this->$name = "I'm $name"; | |
} | |
else { | |
echo "Trying to initialize blank, "; | |
} | |
} | |
function clean() { | |
$this->bar = $this->lol = $this->pub = uninitialized; | |
} | |
} | |
// __initialize will be called only once, on first access | |
$foo = new Foo; | |
var_dump($foo->getBar()); // Getter method bar, Initializing bar, string(7) "I'm bar" | |
var_dump($foo->getBar()); // Getter method bar, string(7) "I'm bar" | |
// magic __get is called first, and inside it's initialized | |
$foo = new Foo; | |
var_dump($foo->bar); // Magic getter bar, Initializing bar, string(7) "I'm bar" | |
var_dump($foo->bar); // Magic getter bar, string(7) "I'm bar" | |
$foo->clean(); | |
var_dump($foo->bar); // Magic getter bar, Initializing bar, string(7) "I'm bar" | |
var_dump($foo->bar); // Magic getter bar, string(7) "I'm bar" | |
// lazy-loading of public properties | |
$foo = new Foo; | |
var_dump($foo->pub); // Initializing pub, string(7) "I'm pub" | |
// normal value remains as expected | |
$foo = new Foo; | |
var_dump($foo->getLol()); // Getter method lol, string(3) "lol" | |
// variable which cannot be initialized | |
$foo = new Foo; | |
var_dump($foo->blank); // Trying to initialize blank, undefined | |
var_dump($foo->blank); // Trying to initialize blank, undefined |
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