In a new blog post today, Hasin Hayder points out an interesting bug he found in the Reflection functionality that's offered in one of the latest PHP5 series release, version 5.2.1 (also found in 5.2.2). It deals with an issue in the ReflectionParameter object.

[Despite the closing of this bug] there is still the following bug alive in ReflectionParameter object, I tested it against the PHP version 5.2.1 . So what is this bug? The reflection parameter cannot retrieve the default value of a parameter if the next parameter has no default value. PHP simply omits all the variables before that variable and return only values after that variable.

He illustrates with a test class that uses reflection to get the parameters for the constructor. Unfortunately, the object only comes back with the last attribute. This is solved later in the comments, however, when it's discovered that the parameters, some of which are optional, are not in the "correct order" - optional parameters should always follow the required.