interface inheritance

all,

previously, on this list and elsewhere, i have raised the topic of
interface inheritance, lamenting that php is void of the feature.
to my utter amazement i discovered that php does in fact support
interface inheritance, reading through some of Marcus Boergers'
code in SPL.. i noticed RecursiveIterator extends Iterator, which
is an internal interface (part of the zend engine), so i thought to
myself, perhaps only internal interfaces can be extended, but
then a quick test proved my suspicions wrong. in fact, interfaces
can even extend multiple parent interfaces, just like java (*ducks*).
here is the sample code so you can see for yourself:

<?php
interface Somethingable {
public function doSomething();
}

interface Crazyfiable {
public function getCrazy();
}

interface Extendable extends Somethingable, Crazyfiable {
public function extend();
}

class SuperClass implements Extendable {
public function doSomething() {
echo 'i did something ..' . PHP_EOL;
}

public function extend() {
echo 'i extended something..' . PHP_EOL;
}

public function getCrazy() {
echo 'im a crazy bastard now!' . PHP_EOL;
}
}

/*
* TEST HERE
*/
$sc = new SuperClass();
$sc->doSomething();
$sc->extend();
$sc->getCrazy();
?>

and the output:
nathan@trident /usr/share/php5/splExperiment/tests $ php
testInterfaceInheritence.php
i did something ..
i extended something..
im a crazy bastard now!

i for one am quite excited. heres to happy adventures in oop-land w/ php!

-nathan

Nathan Nobbe schreef:
> all,
>
> previously, on this list and elsewhere, i have raised the topic of
> interface inheritance, lamenting that php is void of the feature.
> to my utter amazement i discovered that php does in fact support
> interface inheritance, reading through some of Marcus Boergers'
> code in SPL.. i noticed RecursiveIterator extends Iterator, which
> is an internal interface (part of the zend engine), so i thought to
> myself, perhaps only internal interfaces can be extended, but
> then a quick test proved my suspicions wrong. in fact, interfaces
> can even extend multiple parent interfaces, just like java (*ducks*).
> here is the sample code so you can see for yourself:
>
> <?php
> interface Somethingable {
> public function doSomething();
> }
>
> interface Crazyfiable {
> public function getCrazy();
> }
>
> interface Extendable extends Somethingable, Crazyfiable {
> public function extend();
> }
>
> class SuperClass implements Extendable {
> public function doSomething() {
> echo 'i did something ..' . PHP_EOL;
> }
>
> public function extend() {
> echo 'i extended something..' . PHP_EOL;
> }
>
> public function getCrazy() {
> echo 'im a crazy bastard now!' . PHP_EOL;
> }
> }
>
> /*
> * TEST HERE
> */
> $sc = new SuperClass();
> $sc->doSomething();
> $sc->extend();
> $sc->getCrazy();
> ?>
>
> and the output:
> nathan@trident /usr/share/php5/splExperiment/tests $ php
> testInterfaceInheritence.php
> i did something ..
> i extended something..
> im a crazy bastard now!
>
> i for one am quite excited. heres to happy adventures in oop-land w/ php!

nice bit of info!

as an aside, I often use php -r to test snippets like this e.g.:

$> php -r 'echo "foo!";'

very handy and saves having to create a file everytime you test something,
it does mean your forced to use double quotes only in the code (otherwise
the shell misinterprets). I recommend using double quotes in snippets you
post in order to make it easier for people to quickly test your gems for
themselves :-)

>
> -nathan
>