PHP supports Object Oriented Programming (OOP) in the form of classes. Just like in other OOP languages, the classes can be extended for greater reuse of code.
To create an address entry class that contains a person's first and last name and phone number:
class address_book_entry { var $first; var $last; var $number; function set_name($first, $last) { $this->first = $first; $this->last = $last; } function set_number($number) { $this->number = $number; } function display_entry() { echo "<p>Name: " . $this->first . " " . $this->last; echo "<br>Number: " . $this->number; } } //Usage: $entry = &new address_book_entry; $entry->set_name("Jane","Smith"); $entry->set_number("555-555-5555"); $entry->display_entry(); //displays: Name: Jane Smith Number: 555-555-5555
Additionally, you can extend an existing class to create a new class that has the same functionality of the old class, plus any new functionality you add:
class address_book_entry2 extends address_book_entry { var $email; function set_email($email) { $this->email = $email; } function display_entry2() { echo "<p>Name: " . $this->first . " " . $this->last; echo "<br>Number: " . $this->number; echo "<br>Email: " . $this->email; } } //Usage: $entry = &new address_book_entry2; $entry->set_name("Jane","Smith"); $entry->set_number("555-555-5555"); $entry->set_email("jsmith@com.com"); $entry->display_entry(); //displays: Name: Jane Smith Number: 555-555-5555 Email: smith@com.com
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