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Reflections

PHP comes with a complete reflection API that adds the ability to introspect classes, interfaces, functions, methods and extensions. Additionally, the reflection API offers ways to retrieve doc comments for functions, classes and methods.

Please note that certain parts of the internal API are missing the necessary code to work with the reflection extension. E.g., an internal PHP class might be missing reflection data for properties. These few cases are considered bugs, however, so they should be discovered and fixed.

– PHP Reference

Examples

Many examples exist within the reflection documentation, typically within the __construct documentation for each class.

Example: Reflection example from shell (a terminal)

$ php --rf strlen
$ php --rc finfo
$ php --re json
$ php --ri dom

The above example will output something similar to:

Function [ <internal:Core> function strlen ] {

  - Parameters [1] {
    Parameter #0 [ <required> $str ]
  }
}

Class [ <internal:fileinfo> class finfo ] {

  - Constants [0] {
  }

  - Static properties [0] {
  }

  - Static methods [0] {
  }

  - Properties [0] {
  }

  - Methods [4] {
    Method [ <internal:fileinfo, ctor> public method finfo ] {

      - Parameters [2] {
        Parameter #0 [ <optional> $options ]
        Parameter #1 [ <optional> $arg ]
      }
    }

    Method [ <internal:fileinfo> public method set_flags ] {

      - Parameters [1] {
        Parameter #0 [ <required> $options ]
      }
    }

    Method [ <internal:fileinfo> public method file ] {

      - Parameters [3] {
        Parameter #0 [ <required> $filename ]
        Parameter #1 [ <optional> $options ]
        Parameter #2 [ <optional> $context ]
      }
    }

    Method [ <internal:fileinfo> public method buffer ] {

      - Parameters [3] {
        Parameter #0 [ <required> $string ]
        Parameter #1 [ <optional> $options ]
        Parameter #2 [ <optional> $context ]
      }
    }
  }
}

Extension [ <persistent> extension #23 json version 1.2.1 ] {

  - Constants [10] {
    Constant [ integer JSON_HEX_TAG ] { 1 }
    Constant [ integer JSON_HEX_AMP ] { 2 }
    Constant [ integer JSON_HEX_APOS ] { 4 }
    Constant [ integer JSON_HEX_QUOT ] { 8 }
    Constant [ integer JSON_FORCE_OBJECT ] { 16 }
    Constant [ integer JSON_ERROR_NONE ] { 0 }
    Constant [ integer JSON_ERROR_DEPTH ] { 1 }
    Constant [ integer JSON_ERROR_STATE_MISMATCH ] { 2 }
    Constant [ integer JSON_ERROR_CTRL_CHAR ] { 3 }
    Constant [ integer JSON_ERROR_SYNTAX ] { 4 }
  }

  - Functions {
    Function [ <internal:json> function json_encode ] {

      - Parameters [2] {
        Parameter #0 [ <required> $value ]
        Parameter #1 [ <optional> $options ]
      }
    }
    Function [ <internal:json> function json_decode ] {

      - Parameters [3] {
        Parameter #0 [ <required> $json ]
        Parameter #1 [ <optional> $assoc ]
        Parameter #2 [ <optional> $depth ]
      }
    }
    Function [ <internal:json> function json_last_error ] {

      - Parameters [0] {
      }
    }
  }
}

dom

DOM/XML => enabled
DOM/XML API Version => 20031129
libxml Version => 2.7.3
HTML Support => enabled
XPath Support => enabled
XPointer Support => enabled
Schema Support => enabled
RelaxNG Support => enabled

– PHP Reference

Extending

If 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: 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 T {
    protected function x() {}
}

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

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

The above example will output something similar to:

object(My_Reflection_Method)#1 (3) {
  ["visibility"]=>
  array(1) {
    [0]=>
    string(6) "public"
  }
  ["name"]=>
  string(1) "x"
  ["class"]=>
  string(1) "U"
}

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

– PHP Reference

The Reflection class

Description

The ReflectionClass class reports information about a class.

Synopsis

class Reflection {
/* Methods */
public static export(Reflector $reflector, bool $return = false): string
public static getModifierNames(int $modifiers): array
}

*Properties

Predefined constants

ReflectionClass modifiers

– PHP Reference

Reflection classes

– PHP Reference

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