Section 8.16.  Helpful Utility Functions

8.16. Helpful Utility Functions

There are three particular OOP -related functions that will make your life easier, and these are class_exists( ), get_class( ), and get_declared_classes( ). In order, class_exists( ) returns true if the specified class has been declared, get_class( ) returns the class name of the object you pass to it, and get_declared_classes( ) returns an array of all classes of which you can currently create an object.

Here are some examples:

    if ($foo =  = $bar) {
            $sam = new Employee;
    } else {
            $sam = new Dog;
    }

    print "Sam is a " . get_class($sam) . "\n";
    print "Class animal exists: " . class_exists("animal") . "\n\n\n\n";
    print "All declared classes are: " . get_declared_classes( ) . "\n";

The most common use for get_class( ) is when one object can be of several possible types, as in the code above. C++ users will be familiar with the concept of Runtime Type Information (RTTI), and this is pretty much the same thing.