Practical PHP Reflection
Posted in Brain Dump, Code, Programming on March 1st, 2011 by Eric Lamb – 8 CommentsThe Reflection API in PHP is one of those language features that can kind of creep up on you; it’s just not needed for a vast majority of projects. In fact, I’d wager there are a bunch of professional developers who have never had to make use of the Reflection API. Hell, I spent 8 years writing code professionally before I ever had to use it (though, because of some unrelated .NET research I was peripherally aware of it). It’s just not something that really comes up all that often in the day to day coding tasks.
Then, one day, out of nowhere, it comes up. The perfect problem where the Reflection API appears to be the perfect solution. For me this came up a couple months ago while I was working on a European zip code radius project that had to be built using one of those obfuscated and ill documented 3rd party commercial programs (nothing worse than when the platform is forced on you). So, I had to use this program that was intentionally encoded to prevent me from doing what I wanted to do. I couldn’t even look at the code; it was completely obfuscated.
Before getting into things it should be noted that the Reflection API is capable above and beyond what I’m outlining; usually for the kind of high level stuff like core Zend Framework components and anything you’d want way abstracted.
So, yeah, weird problem.
This is where reflection comes in for me. It was made for problems like the above; according to the manual:
PHP 5 comes with a complete reflection API that adds the ability to reverse-engineer classes, interfaces, functions, methods and extensions. Additionally, the reflection API offers ways to retrieve doc comments for functions, classes and methods.
So, the theory was that I could use the Reflection API to look into the obfuscated code and get some insight into what was going on and what I had to work with. I figured that, at the least, if I could see what methods, properties and comments the code had; maybe I’d get some clue about what the code was about. Using, for example, the internal PHP class “SimpleXMLElement” it’s real simple to get a nice map of the class by calling the class ReflectionClass and passing the name of the class you want to get details on as a parameter like the below:
1 2 3 4 | <?php $reflector = new ReflectionClass("SimpleXMLElement"); echo $reflector; ?> |
The above outputs an eye gouging but verbose class map:
Class [ <internal:SimpleXML> <iterateable> class SimpleXMLElement implements Traversable ] { - Constants [0] { } - Static properties [0] { } - Static methods [0] { } - Properties [0] { } - Methods [14] { Method [ <internal:SimpleXML, ctor> final public method __construct ] { } Method [ <internal:SimpleXML> public method asXML ] { } Method [ <internal:SimpleXML> public method saveXML ] { } Method [ <internal:SimpleXML> public method xpath ] { } Method [ <internal:SimpleXML> public method registerXPathNamespace ] { } Method [ <internal:SimpleXML> public method attributes ] { } Method [ <internal:SimpleXML> public method children ] { } Method [ <internal:SimpleXML> public method getNamespaces ] { } Method [ <internal:SimpleXML> public method getDocNamespaces ] { } Method [ <internal:SimpleXML> public method getName ] { } Method [ <internal:SimpleXML> public method addChild ] { } Method [ <internal:SimpleXML> public method addAttribute ] { } Method [ <internal:SimpleXML> public method __toString ] { } Method [ <internal:SimpleXML> public method count ] { } } }
As you can see, the above lists every property, method and constant about a class along with any parent classes and interfaces. If there were any variables the methods accepted it would also list those as well but SimpleXMLElement doesn’t have any.
It’s also possible to get the individual elements on a one by one basis while using the ReflectionClass object; for example the below methods returns the class name, any comments (if they’re in docblock format), the constants, parent class, constructor and default properties for the class DateTime.
<?php $reflector = new ReflectionClass("DateTime"); echo "Class name: ".$reflector->getName()."\n"; echo "Doc Comment:".var_dump($reflector->getDocComment())."\n"; echo "Contants: ".var_dump($reflector->getConstants())."\n"; echo "Parent Class: ".var_dump($reflector->getParentClass())."\n"; echo "Constructor: ".var_dump($reflector->getConstructor())."\n"; echo "Default Properties: ".var_dump($reflector->getDefaultProperties())."\n"; ?>
Outputs
Class name: DateTime Doc Comment: bool(false) Contants: array(11) { ["ATOM"]=> string(13) "Y-m-d\TH:i:sP" ["COOKIE"]=> string(16) "l, d-M-y H:i:s T" ["ISO8601"]=> string(13) "Y-m-d\TH:i:sO" ["RFC822"]=> string(16) "D, d M y H:i:s O" ["RFC850"]=> string(16) "l, d-M-y H:i:s T" ["RFC1036"]=> string(16) "D, d M y H:i:s O" ["RFC1123"]=> string(16) "D, d M Y H:i:s O" ["RFC2822"]=> string(16) "D, d M Y H:i:s O" ["RFC3339"]=> string(13) "Y-m-d\TH:i:sP" ["RSS"]=> string(16) "D, d M Y H:i:s O" ["W3C"]=> string(13) "Y-m-d\TH:i:sP" } Parent Class: bool(false) Constructor: object(ReflectionMethod)#2 (2) { ["name"]=> string(11) "__construct" ["class"]=> string(8) "DateTime" } Default Properties: array(0) { }
Check out the documentation; there are a bunch of other details you can get from other methods.
This is really just the tip of the iceberg though. There are other classes that allow even deeper insight into functions, methods, extensions and much more. Definitely worth checking out.
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