I understand that my question is somehow wrong, but I’m still trying to solve this problem.
I have an interface Programmer
:
interface Programmer { public function writeCode(); }
and a couple of namespaced classes:
StudentsBjarneProgrammer
(implementsProgrammer
)StudentsCharlieActor
(implementsActor
)
I have this class names stored in array $students = array("BjarneProgrammer", "CharlieActor");
I want to write a function, that will return an instance of class if it’s implementing Programmer
interface.
Examples:
getStudentObject($students[0]);
– It should return an instance of BjarneProgrammer
because it’s implementing Programmer.
getStudentObject($students[1]);
– It should return false
because Charlie is not a Programmer.
I tried it using instanceof
operator, but the main problem is that I do not want to instantiate an object if it’s not implementing Programmer.
I checked How to load php code dynamically and check if classes implement interface, but there is no appropriate answer as I don’t want to create object unless it’s returned by function.
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Answer
You can use class_implements (requires PHP 5.1.0
)
interface MyInterface { } class MyClass implements MyInterface { } $interfaces = class_implements('MyClass'); if($interfaces && in_array('MyInterface', $interfaces)) { // Class MyClass implements interface MyInterface }
You can pass the class name
as a string as function’s argument. Also, you may use Reflection
$class = new ReflectionClass('MyClass'); if ( $class->implementsInterface('MyInterface') ) { // Class MyClass implements interface MyInterface }
Update : (You may try something like this)
interface Programmer { public function writeCode(); } interface Actor { // ... } class BjarneProgrammer implements Programmer { public function writeCode() { echo 'Implemented writeCode method from Programmer Interface!'; } }
Function that checks and returns instanse/false
function getStudentObject($cls) { $class = new ReflectionClass($cls); if ( $class->implementsInterface('Programmer') ) { return new $cls; } return false; }
Get an instance or false
$students = array("BjarneProgrammer", "CharlieActor"); $c = getStudentObject($students[0]); if($c) { $c->writeCode(); }