Object-Oriented PHP

__isset and __unset

PHP 5.1.0 introduces the magic methods __isset and __unset. These methods are called indirectly by the built-in PHP functions isset and unset. The need for these magic methods results directly from the existence of magic set and get methods for undeclared data members. The magic method __isset will be called whenever isset is used with an undeclared data member.

Suppose you want to determine whether the name variable of your Person instance in Listing 13-1 has been set. If you execute the code isset($t->name);, the return value will be false. To properly check whether an undeclared data member has been set, you need to define an __isset method. Redo the code for the Person class to incorporate a magic __isset method (see ...