Interfaces in PHP

By: Andi, Stig and Derick Emailed: 1699 times Printed: 2200 times    

Latest comments
By: rohit kumar - how this program is work
By: Kirti - Hi..thx for the hadoop in
By: Spijker - I have altered the code a
By: ali mohammed - why we use the java in ne
By: ali mohammed - why we use the java in ne
By: mizhelle - when I exported the data
By: raul - no output as well, i'm ge
By: Rajesh - thanx very much...
By: Suindu De - Suppose we are executing

Class inheritance enables you to describe a parent-child relationship between classes. For example, you might have a base class Shape from which both Square and Circle derive. However, you might often want to add additional "interfaces" to classes, basically meaning additional contracts to which the class must adhere. This is achieved in C++ by using multiple inheritance and deriving from two classes. PHP chose interfaces as an alternative to multiple inheritance, which allows you to specify additional contracts a class must follow. An interface is declared similar to a class but only includes function prototypes (without implementation) and constants. Any class that "implements" this interface automatically has the interface’s constants defined and, as the implementing class, needs to supply the function definitions for the interface’s function prototypes that are all abstract methods (unless you declare the implementing class as abstract).

To implement an interface, use the following syntax:

class A implements B, C, ... {

...

}

Classes that implement an interface have an instanceof (is-a) relationship with the interface; for example, if class A implements interface myInterface, the following results in '$obj is-A myInterface' printing:

$obj = new A();

if ($obj instanceof myInterface) {

print '$obj is-A myInterface';

}

The following example defines an interface called Loggable, which classes can implement to define what information will be logged by the MyLog() function. Objects of classes that don’t implement this interface and are passed to the MyLog() function result in an error message being printed:

interface Loggable {

function logString();

}

class Person implements Loggable {

private $name, $address, $idNumber, $age;

function logString() {

return "class Person: name = $this->name, ID = $this->idNumber\n";

}

}

class Product implements Loggable {

private $name, $price, $expiryDate;

function logString() {

return "class Product: name = $this->name, price = $this->price\n";

}

}

function MyLog($obj) {

if ($obj instanceof Loggable) {

print $obj->logString();

} else {

print "Error: Object doesn’t support Loggable interface\n";

}

}

$person = new Person();

// ...

$product = new Product();

MyLog($person);

MyLog($product);

Note: Interfaces are always considered to be public; therefore, you can’t specify access modifiers for the method prototypes in the interface’s declaration.

Note: You may not implement multiple interfaces that clash with each other (for example, interfaces that define the same constants or methods).


PHP Home | All PHP Tutorials | Latest PHP Tutorials

Sponsored Links

If this tutorial doesn't answer your question, or you have a specific question, just ask an expert here. Post your question to get a direct answer.



Bookmark and Share

Comments(0)


Be the first one to add a comment

Your name (required):


Your email(required, will not be shown to the public):


Your sites URL (optional):


Your comments:



More Tutorials by Andi, Stig and Derick
Execution Lifetime of a PHP script
preg_split() and explode() in PHP
preg_replace() and preg_replace_callback() in PHP
preg_match(), function preg_match_all(), preg_grep() in PHP
tmpfile() in PHP
Renaming and Removing Files in PHP
Locking files in PHP
File Handling in PHP
Handling BLOB in PHP and MySQL
Using Sessions in PHP
Using Cookies in PHP
Using PEAR::Crypt_HMAC in PHP
Using HMAC Verification in PHP
Input Validation in PHP
__autoload() METHOD in PHP

More Tutorials in PHP
PHP code to import from CSV file to MySQL
PHP code to write to a CSV file from MySQL query
PHP code to write to a CSV file for Microsoft Applications
Convert XML to CSV in PHP
Password must include both numeric and alphabetic characters - Magento
PHP file upload (Large Files)
PHP file upload prompts authentication for anonymous users
PHP file upload with IIS on windows XP/2000 etc
Error: Length parameter must be greater than 0
Multiple File Upload in PHP using IFRAME
Resume or Pause File Uploads in PHP
Exception in module wampmanager.exe at 000F15A0 in Windows 8
Handling file locks in PHP
HTML table output using Nested for loops in PHP
Count occurrences of a character in a String in PHP

More Latest News
Most Viewed Articles (in PHP )
isset() function in PHP
Using Text file as database in PHP
Convert IP address to integer and back to IP address in PHP
Traversing Arrays Using foreach in PHP
public, protected, and private Properties in PHP
parent:: AND self:: in PHP
Using Cookies in PHP
preg_replace() and preg_replace_callback() in PHP
preg_split() and explode() in PHP
GDBM, NDBM, DB2, DB3, DBM, and CDB Databases in PHP
Parent: child process exited with status 3221225477 -- Restarting
Function to return number of digits of an integer in PHP
Get the first and last day of the month in PHP
Multiple File Upload in PHP using IFRAME
Convert XML to CSV in PHP
Most Emailed Articles (in PHP)
Traversing Arrays Using foreach in PHP
preg_split() and explode() in PHP
GDBM, NDBM, DB2, DB3, DBM, and CDB Databases in PHP
Sorting an Array in PHP
fixEncoding in PHP
Assignment operators in PHP
switch Statements in PHP
preg_match(), function preg_match_all(), preg_grep() in PHP
Reading .CSV file in PHP
Encrypting files using GnuPG (GPG) via PHP
Where does the PHP run?
Setting up PHP in Windows 2003 Server IIS7, and WinXP 64
Perl's Encoding::FixLatin equivalent in PHP
break out of an if() block in PHP
PHP file upload with IIS on windows XP/2000 etc