Obtain information about a class

PHP5 includes interesting APIs to obtain information (list of members and methods) about the internal classes or interfaces.

Example of PHP5 interesting classes/interfaces: Exception, Iterator.

To obtain information about a class, instantiate the class ReflectionClass passing the name of the class we want information about. Now pass that instance to the static method export() of the class Reflection. The method print a list of detailed information about the class (see below the example):

Reflection::export(new ReflectionClass('Iterator'));

output::

Interface [ interface Iterator implements Traversable ] {

[...]

- Methods [5] {

Method [ abstract public method current ] { }

Method [ abstract public method next ] { }

Method [ abstract public method key ] { }

Method [ abstract public method valid ] { }

Method [ abstract public method rewind ] { }

}

}

To obtain information about a PHP method, use the ReflectionFunction class, and the static method export() of the class Reflection.

In this example we'll obtain information about the PHP function str_replace(). The export method show the parameters order, if required or not, and if is taken by value or reference.

Reflection::export(new ReflectionFunction('str_replace'));

Function [ function str_replace ] {

- Parameters [4] {

Parameter #0 [ $search ]

Parameter #1 [ $replace ]

Parameter #2 [ $subject ]

Parameter #3 [ &$replace_count ]

}

}

For user defined function, there are other interesting methods of the class ReflectionFunction. Here are some of them:

• public bool isInternal()
• 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()

Similarly, there is a class to get information about the parameters: ReflectionParameter, which contain methods to retrieve arguments details (isArray(), getDefaultValue(), etc...).

Other APIs classes: ReflectionProperty (information about class properties) and ReflectionExtension (info about extensions)