ReflectionClass::isInstantiable

(PHP 5)

ReflectionClass::isInstantiableChecks if the class is instantiable

Descrizione

public bool ReflectionClass::isInstantiable ( void )

Checks if the class is instantiable.

Elenco dei parametri

Questa funzione non contiene parametri.

Valori restituiti

Restituisce TRUE in caso di successo, FALSE in caso di fallimento.

Esempi

Example #1 ReflectionClass::isInstantiable() example

<?php
class { }

interface 
iface {
    function 
f1();
}

class 
ifaceImpl implements iface {
    function 
f1() {}
}

abstract class 
abstractClass {
    function 
f1() { }
    abstract function 
f2();
}

class 
extends abstractClass {
    function 
f2() { }
}

class 
privateConstructor {
    private function 
__construct() { }
}

$classes = array(
    
"C",
    
"iface",
    
"ifaceImpl",
    
"abstractClass",
    
"D",
    
"privateConstructor",
);

foreach(
$classes  as $class ) {
    
$reflectionClass = new ReflectionClass($class);
    echo 
"Is $class instantiable?  ";
    
var_dump($reflectionClass->IsInstantiable()); 
}

?>

Il precedente esempio visualizzerĂ :

Is C instantiable?  bool(true)
Is iface instantiable?  bool(false)
Is ifaceImpl instantiable?  bool(true)
Is abstractClass instantiable?  bool(false)
Is D instantiable?  bool(true)
Is privateConstructor instantiable?  bool(false)

Vedere anche:

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User Contributed Notes 1 note

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0
shaun at slickdesign dot com dot au
2 days ago
An example missing from the documentation is that `ReflectionClass::isInstantiable` will also return false for traits, as well as interfaces and abstract classes.

<?php
trait t {
   
// Optional trait methods and properties etc.
}

$reflectionClass = new ReflectionClass("t");
var_dump($reflectionClass->isInstantiable()); // bool(false)
?>

As for classes with private constructors, it is still possible to create an instance by either bypassing the constructor using `ReflectionClass::newInstanceWithoutConstructor`, or by ensuring the class has a method which can create a new instance.

<?php
class p {
    private function
__construct() {
       
// Optional constructor logic - not called when ReflectionClass::newInstanceWithoutConstructor is used.
   
}

    public static function
create() {
        return new
p;
    }

   
// Optional methods and properties etc.
}

// Class is not classed as instantiable.
$reflectionClass = new ReflectionClass("p");
var_dump($reflectionClass->isInstantiable()); // bool(false)

// We're still able to create an instance using one of the two methods.
$p = p::create();
$p = $reflectionClass->newInstanceWithoutConstructor();
?>

The same is also true for protected constructors, however, the class can be instantiated from either parent or child methods, depending on where the constructor is defined.

<?php
class p {
    protected function
__construct() {
       
// Optional constructor logic.
   
}

    public static function
create( $class = "" ) {
        if (!
$class) {
           
$class = get_called_class();
        }
        return new
$class;
    }

   
// Optional parent methods and properties etc.
}

class
c extends p
{
   
// Optional child methods and properties etc.
}

// Both child and parent static methods have access to each other's protected constructor.
$p = c::create("p");
$c = p::create("c");

// Both are still not classed as being instantiable.
$reflectionClassP = new ReflectionClass("p");
$reflectionClassC = new ReflectionClass("c");
var_dump($reflectionClassP->isInstantiable()); // bool(false)
var_dump($reflectionClassC->isInstantiable()); // bool(false)

// We're still able to bypass the constructor and create an instance for each.
$p = $reflectionClassP->newInstanceWithoutConstructor();
$c = $reflectionClassC->newInstanceWithoutConstructor();
?>
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