PYTHON Reflection

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PHP Reflection

PHP original manual for Reflection [ show | php.net ]

Reflection

Introduction

PHP 5 comes with a complete reflection API that adds the ability to reverse-engineer classes, interfaces, functions and methods as well as extensions. Additionally, the reflection API also offers ways of retrieving doc comments for functions, classes and methods.

The reflection API is an object-oriented extension to the Zend Engine, consisting of the following classes:

<?php
class Reflection { }
interface 
Reflector { }
class 
ReflectionException extends Exception { }
class 
ReflectionFunction extends ReflectionFunctionAbstract implements Reflector { }
class 
ReflectionParameter implements Reflector { }
class 
ReflectionMethod extends ReflectionFunctionAbstract implements Reflector { }
class 
ReflectionClass implements Reflector { }
class 
ReflectionObject extends ReflectionClass { }
class 
ReflectionProperty implements Reflector { }
class 
ReflectionExtension implements Reflector { }
?>

Note: For details on these classes, have a look at the next chapters.

If we were to execute the code in the example below:

Example #1 Basic usage of the reflection API

<?php
Reflection
::export(new ReflectionClass('Exception'));
?>

The above example will output:

Class [ <internal> class Exception ] {

  - Constants [0] {
  }

  - Static properties [0] {
  }

  - Static methods [0] {
  }

  - Properties [6] {
    Property [ <default> protected $message ]
    Property [ <default> private $string ]
    Property [ <default> protected $code ]
    Property [ <default> protected $file ]
    Property [ <default> protected $line ]
    Property [ <default> private $trace ]
  }

  - Methods [9] {
    Method [ <internal> final private method __clone ] {
    }

    Method [ <internal, ctor> public method __construct ] {

      - Parameters [2] {
        Parameter #0 [ <optional> $message ]
        Parameter #1 [ <optional> $code ]
      }
    }

    Method [ <internal> final public method getMessage ] {
    }

    Method [ <internal> final public method getCode ] {
    }

    Method [ <internal> final public method getFile ] {
    }

    Method [ <internal> final public method getLine ] {
    }

    Method [ <internal> final public method getTrace ] {
    }

    Method [ <internal> final public method getTraceAsString ] {
    }

    Method [ <internal> public method __toString ] {
    }
  }
}

Reflector

Reflector is an interface implemented by all exportable Reflection classes.

<?php
interface Reflector
{
    public 
string __toString()
    public static 
string export()
}
?>

ReflectionException

ReflectionException extends the standard Exception and is thrown by Reflection API. No specific methods or properties are introduced.

ReflectionFunction

The ReflectionFunction class lets you reverse-engineer functions.

<?php
class ReflectionFunction extends ReflectionFunctionAbstract implements Reflector
{
    final private 
__clone()
    public 
void __construct(string name)
    public 
string __toString()
    public static 
string export(string namebool return)
    public 
string getName()
    public 
bool isInternal()
    public 
bool isDisabled()
    public 
mixed getClosure() /* As of PHP 5.3.0 */
    
public bool isUserDefined()
    public 
string getFileName()
    public 
int getStartLine()
    public 
int getEndLine()
    public 
string getDocComment()
    public array 
getStaticVariables()
    public 
mixed invoke([mixed args [, ...]])
    public 
mixed invokeArgs(array args)
    public 
bool returnsReference()
    public 
ReflectionParameter[] getParameters()
    public 
int getNumberOfParameters()
    public 
int getNumberOfRequiredParameters()
}
?>

Parent class ReflectionFunctionAbstract has the same methods except invoke(), invokeArgs(), export() and isDisabled().

Note: getNumberOfParameters() and getNumberOfRequiredParameters() were added in PHP 5.0.3, while invokeArgs() was added in PHP 5.1.0.

To introspect a function, you will first have to create an instance of the ReflectionFunction class. You can then call any of the above methods on this instance.

Example #2 Using the ReflectionFunction class

<?php
/**
 * A simple counter
 *
 * @return    int
 */
function counter()
{
    static 
$c 0;
    return 
$c++;
}

// Create an instance of the ReflectionFunction class
$func = new ReflectionFunction('counter');

// Print out basic information
printf(
    
"===> The %s function '%s'\n".
    
"     declared in %s\n".
    
"     lines %d to %d\n",
    
$func->isInternal() ? 'internal' 'user-defined',
    
$func->getName(),
    
$func->getFileName(),
    
$func->getStartLine(),
    
$func->getEndline()
);

// Print documentation comment
printf("---> Documentation:\n %s\n"var_export($func->getDocComment(), 1));

// Print static variables if existant
if ($statics $func->getStaticVariables())
{
    
printf("---> Static variables: %s\n"var_export($statics1));
}

// Invoke the function
printf("---> Invokation results in: ");
var_dump($func->invoke());


// you may prefer to use the export() method
echo "\nReflectionFunction::export() results:\n";
echo 
ReflectionFunction::export('counter');
?>

Note: The method invoke() accepts a variable number of arguments which are passed to the function just as in call_user_func().

ReflectionParameter

The ReflectionParameter class retrieves information about a function's or method's parameters.

<?php
class ReflectionParameter implements Reflector
{
    final private 
__clone()
    public 
void __construct(string function, string parameter)
    public 
string __toString()
    public static 
string export(mixed function, mixed parameterbool return)
    public 
string getName()
    public 
bool isPassedByReference()
    public 
ReflectionClass getDeclaringClass()
    public 
ReflectionClass getClass()
    public 
bool isArray()
    public 
bool allowsNull()
    public 
bool isPassedByReference()
    public 
bool isOptional()
    public 
bool isDefaultValueAvailable()
    public 
mixed getDefaultValue()
    public 
int getPosition()
}
?>

Note: getDefaultValue(), isDefaultValueAvailable() and isOptional() were added in PHP 5.0.3, while isArray() was added in PHP 5.1.0. getDeclaringFunction() and getPosition() were added in PHP 5.2.3.

To introspect function parameters, you will first have to create an instance of the ReflectionFunction or ReflectionMethod classes and then use their getParameters() method to retrieve an array of parameters.

Example #3 Using the ReflectionParameter class

<?php
function foo($a$b$c) { }
function 
bar(Exception $a, &$b$c) { }
function 
baz(ReflectionFunction $a$b 1$c null) { }
function 
abc() { }

// Create an instance of ReflectionFunction with the
// parameter given from the command line.
$reflect = new ReflectionFunction($argv[1]);

echo 
$reflect;

foreach (
$reflect->getParameters() as $i => $param) {
    
printf(
        
"-- Parameter #%d: %s {\n".
        
"   Class: %s\n".
        
"   Allows NULL: %s\n".
        
"   Passed to by reference: %s\n".
        
"   Is optional?: %s\n".
        
"}\n",
        
$i// $param->getPosition() can be used from PHP 5.2.3
        
$param->getName(),
        
var_export($param->getClass(), 1),
        
var_export($param->allowsNull(), 1),
        
var_export($param->isPassedByReference(), 1),
        
$param->isOptional() ? 'yes' 'no'
    
);
}
?>

ReflectionClass

The ReflectionClass class lets you reverse-engineer classes and interfaces.

<?php
class ReflectionClass implements Reflector
{
    final private 
__clone()
    public 
void __construct(string name)
    public 
string __toString()
    public static 
string export(mixed class, bool return)
    public 
string getName()
    public 
bool isInternal()
    public 
bool isUserDefined()
    public 
bool isInstantiable()
    public 
bool hasConstant(string name)
    public 
bool hasMethod(string name)
    public 
bool hasProperty(string name)
    public 
string getFileName()
    public 
int getStartLine()
    public 
int getEndLine()
    public 
string getDocComment()
    public 
ReflectionMethod getConstructor()
    public 
ReflectionMethod getMethod(string name)
    public 
ReflectionMethod[] getMethods()
    public 
ReflectionProperty getProperty(string name)
    public 
ReflectionProperty[] getProperties()
    public array 
getConstants()
    public 
mixed getConstant(string name)
    public 
ReflectionClass[] getInterfaces()
    public 
bool isInterface()
    public 
bool isAbstract()
    public 
bool isFinal()
    public 
int getModifiers()
    public 
bool isInstance(stdclass object)
    public 
stdclass newInstance(mixed args)
    public 
stdclass newInstanceArgs(array args)
    public 
ReflectionClass getParentClass()
    public 
bool isSubclassOf(ReflectionClass class)
    public array 
getStaticProperties()
    public 
mixed getStaticPropertyValue(string name [, mixed default])
    public 
void setStaticPropertyValue(string namemixed value)
    public array 
getDefaultProperties()
    public 
bool isIterateable()
    public 
bool implementsInterface(string name)
    public 
ReflectionExtension getExtension()
    public 
string getExtensionName()
}
?>

Note: hasConstant(), hasMethod(), hasProperty(), getStaticPropertyValue() and setStaticPropertyValue() were added in PHP 5.1.0, while newInstanceArgs() was added in PHP 5.1.3.

To introspect a class, you will first have to create an instance of the ReflectionClass class. You can then call any of the above methods on this instance.

Example #4 Using the ReflectionClass class

<?php
interface Serializable
{
    
// ...
}

class 
Object
{
    
// ...
}

/**
 * A counter class
 */
class Counter extends Object implements Serializable
{
    const 
START 0;
    private static 
$c Counter::START;

    
/**
     * Invoke counter
     *
     * @access  public
     * @return  int
     */
    
public function count() {
        return 
self::$c++;
    }
}

// Create an instance of the ReflectionClass class
$class = new ReflectionClass('Counter');

// Print out basic information
printf(
    
"===> The %s%s%s %s '%s' [extends %s]\n" .
    
"     declared in %s\n" .
    
"     lines %d to %d\n" .
    
"     having the modifiers %d [%s]\n",
        
$class->isInternal() ? 'internal' 'user-defined',
        
$class->isAbstract() ? ' abstract' '',
        
$class->isFinal() ? ' final' '',
        
$class->isInterface() ? 'interface' 'class',
        
$class->getName(),
        
var_export($class->getParentClass(), 1),
        
$class->getFileName(),
        
$class->getStartLine(),
        
$class->getEndline(),
        
$class->getModifiers(),
        
implode(' 'Reflection::getModifierNames($class->getModifiers()))
);

// Print documentation comment
printf("---> Documentation:\n %s\n"var_export($class->getDocComment(), 1));

// Print which interfaces are implemented by this class
printf("---> Implements:\n %s\n"var_export($class->getInterfaces(), 1));

// Print class constants
printf("---> Constants: %s\n"var_export($class->getConstants(), 1));

// Print class properties
printf("---> Properties: %s\n"var_export($class->getProperties(), 1));

// Print class methods
printf("---> Methods: %s\n"var_export($class->getMethods(), 1));

// If this class is instantiable, create an instance
if ($class->isInstantiable()) {
    
$counter $class->newInstance();

    echo 
'---> $counter is instance? ';
    echo 
$class->isInstance($counter) ? 'yes' 'no';

    echo 
"\n---> new Object() is instance? ";
    echo 
$class->isInstance(new Object()) ? 'yes' 'no';
}
?>

Note: The method newInstance() accepts a variable number of arguments which are passed to the function just as in call_user_func().

Note: $class = new ReflectionClass('Foo'); $class->isInstance($arg) is equivalent to $arg instanceof Foo or is_a($arg, 'Foo').

ReflectionObject

The ReflectionObject class lets you reverse-engineer objects.

<?php
class ReflectionObject extends ReflectionClass
{
    final private 
__clone()
    public 
void __construct(mixed object)
    public 
string __toString()
    public static 
string export(mixed objectbool return)
}
?>

ReflectionMethod

The ReflectionMethod class lets you reverse-engineer class methods.

<?php
class ReflectionMethod extends ReflectionFunctionAbstract implements Reflector
{
    public 
void __construct(mixed class, string name)
    public 
string __toString()
    public static 
string export(mixed class, string namebool return)
    public 
mixed invoke(stdclass object [, mixed args [, ...]])
    public 
mixed invokeArgs(stdclass object, array args)
    public 
bool isFinal()
    public 
bool isAbstract()
    public 
bool isPublic()
    public 
bool isPrivate()
    public 
bool isProtected()
    public 
bool isStatic()
    public 
bool isConstructor()
    public 
bool isDestructor()
    public 
int getModifiers()
    public 
mixed getClosure() /* As of PHP 5.3.0 */
    
public ReflectionClass getDeclaringClass()

    
// Inherited from ReflectionFunctionAbstract
    
final private __clone()
    public 
string getName()
    public 
bool isInternal()
    public 
bool isUserDefined()
    public 
string getFileName()
    public 
int getStartLine()
    public 
int getEndLine()
    public 
string getDocComment()
    public array 
getStaticVariables()
    public 
bool returnsReference()
    public 
ReflectionParameter[] getParameters()
    public 
int getNumberOfParameters()
    public 
int getNumberOfRequiredParameters()
}
?>

To introspect a method, you will first have to create an instance of the ReflectionMethod class. You can then call any of the above methods on this instance.

Example #5 Using the ReflectionMethod class

<?php
class Counter
{
    private static 
$c 0;

    
/**
     * Increment counter
     *
     * @final
     * @static
     * @access  public
     * @return  int
     */
    
final public static function increment()
    {
        return ++
self::$c;
    }
}

// Create an instance of the ReflectionMethod class
$method = new ReflectionMethod('Counter''increment');

// Print out basic information
printf(
    
"===> The %s%s%s%s%s%s%s method '%s' (which is %s)\n" .
    
"     declared in %s\n" .
    
"     lines %d to %d\n" .
    
"     having the modifiers %d[%s]\n",
        
$method->isInternal() ? 'internal' 'user-defined',
        
$method->isAbstract() ? ' abstract' '',
        
$method->isFinal() ? ' final' '',
        
$method->isPublic() ? ' public' '',
        
$method->isPrivate() ? ' private' '',
        
$method->isProtected() ? ' protected' '',
        
$method->isStatic() ? ' static' '',
        
$method->getName(),
        
$method->isConstructor() ? 'the constructor' 'a regular method',
        
$method->getFileName(),
        
$method->getStartLine(),
        
$method->getEndline(),
        
$method->getModifiers(),
        
implode(' 'Reflection::getModifierNames($method->getModifiers()))
);

// Print documentation comment
printf("---> Documentation:\n %s\n"var_export($method->getDocComment(), 1));

// Print static variables if existant
if ($statics$method->getStaticVariables()) {
    
printf("---> Static variables: %s\n"var_export($statics1));
}

// Invoke the method
printf("---> Invokation results in: ");
var_dump($method->invoke(NULL));
?>

Example #6 Getting closure using ReflectionMethod class

<?php

class Example {
    static function 
printer () {
        echo 
"Hello World!\n";
    }
}

$class = new ReflectionClass('Example');
$method $class->getMethod('printer');
$closure $method->getClosure(); /* As of PHP 5.3.0 */
$closure(); // Hello World!

?>

Note: Trying to invoke private, protected or abstract methods will result in an exception being thrown from the invoke() method.

Note: For static methods as seen above, you should pass NULL as the first argument to invoke(). For non-static methods, pass an instance of the class.

ReflectionProperty

The ReflectionProperty class lets you reverse-engineer class properties.

<?php
class ReflectionProperty implements Reflector
{
    final private 
__clone()
    public 
void __construct(mixed class, string name)
    public 
string __toString()
    public static 
string export(mixed class, string namebool return)
    public 
string getName()
    public 
bool isPublic()
    public 
bool isPrivate()
    public 
bool isProtected()
    public 
bool isStatic()
    public 
bool isDefault()
    public 
void setAccessible() /* As of PHP 5.3.0 */
    
public int getModifiers()
    public 
mixed getValue(stdclass object)
    public 
void setValue(stdclass objectmixed value)
    public 
ReflectionClass getDeclaringClass()
    public 
string getDocComment()
}
?>

Note: getDocComment() was added in PHP 5.1.0. setAccessible() was added in PHP 5.3.0.

To introspect a property, you will first have to create an instance of the ReflectionProperty class. You can then call any of the above methods on this instance.

Example #7 Using the ReflectionProperty class

<?php
class String
{
    public 
$length  5;
}

// Create an instance of the ReflectionProperty class
$prop = new ReflectionProperty('String''length');

// Print out basic information
printf(
    
"===> The%s%s%s%s property '%s' (which was %s)\n" .
    
"     having the modifiers %s\n",
        
$prop->isPublic() ? ' public' '',
        
$prop->isPrivate() ? ' private' '',
        
$prop->isProtected() ? ' protected' '',
        
$prop->isStatic() ? ' static' '',
        
$prop->getName(),
        
$prop->isDefault() ? 'declared at compile-time' 'created at run-time',
        
var_export(Reflection::getModifierNames($prop->getModifiers()), 1)
);

// Create an instance of String
$obj= new String();

// Get current value
printf("---> Value is: ");
var_dump($prop->getValue($obj));

// Change value
$prop->setValue($obj10);
printf("---> Setting value to 10, new value is: ");
var_dump($prop->getValue($obj));

// Dump object
var_dump($obj);
?>

Example #8 Getting value from private and protected properties using ReflectionProperty class

<?php

class Foo {
    public 
$x 1;
    protected 
$y 2;
    private 
$z 3;
}

$obj = new Foo;

$prop = new ReflectionProperty('Foo''y');
$prop->setAccessible(true); /* As of PHP 5.3.0 */
var_dump($prop->getValue($obj)); // int(2)

$prop = new ReflectionProperty('Foo''z');
$prop->setAccessible(true); /* As of PHP 5.3.0 */
var_dump($prop->getValue($obj)); // int(2)

?>

Note: Trying to get or set private or protected class property's values will result in an exception being thrown.

ReflectionExtension

The ReflectionExtension class lets you reverse-engineer extensions. You can retrieve all loaded extensions at runtime using the get_loaded_extensions().

<?php
class ReflectionExtension implements Reflector {
    final private 
__clone()
    public 
void __construct(string name)
    public 
string __toString()
    public static 
string export(string namebool return)
    public 
string getName()
    public 
string getVersion()
    public 
ReflectionFunction[] getFunctions()
    public array 
getConstants()
    public array 
getINIEntries()
    public 
ReflectionClass[] getClasses()
    public array 
getClassNames()
    public 
string info()
}
?>

To introspect an extension, you will first have to create an instance of the ReflectionExtension class. You can then call any of the above methods on this instance.

Example #9 Using the ReflectionExtension class

<?php
// Create an instance of the ReflectionExtension class
$ext = new ReflectionExtension('standard');

// Print out basic information
printf(
    
"Name        : %s\n" .
    
"Version     : %s\n" .
    
"Functions   : [%d] %s\n" .
    
"Constants   : [%d] %s\n" .
    
"INI entries : [%d] %s\n" .
    
"Classes     : [%d] %s\n",
        
$ext->getName(),
        
$ext->getVersion() ? $ext->getVersion() : 'NO_VERSION',
        
sizeof($ext->getFunctions()),
        
var_export($ext->getFunctions(), 1),

        
sizeof($ext->getConstants()),
        
var_export($ext->getConstants(), 1),

        
sizeof($ext->getINIEntries()),
        
var_export($ext->getINIEntries(), 1),

        
sizeof($ext->getClassNames()),
        
var_export($ext->getClassNames(), 1)
);
?>

Extending the reflection classes

In case you want to create specialized versions of the built-in classes (say, for creating colorized HTML when being exported, having easy-access member variables instead of methods or having utility methods), you may go ahead and extend them.

Example #10 Extending the built-in classes

<?php
/**
 * My Reflection_Method class
 */
class My_Reflection_Method extends ReflectionMethod
{
    public 
$visibility = array();

    public function 
__construct($o$m)
    {
        
parent::__construct($o$m);
        
$this->visibility Reflection::getModifierNames($this->getModifiers());
    }
}

/**
 * Demo class #1
 *
 */
class {
    protected function 
x() {}
}

/**
 * Demo class #2
 *
 */
class extends {
    function 
x() {}
}

// Print out information
var_dump(new My_Reflection_Method('U''x'));
?>

Note: Caution: If you're overwriting the constructor, remember to call the parent's constructor _before_ any code you insert. Failing to do so will result in the following: Fatal error: Internal error: Failed to retrieve the reflection object