PHP 7.0.6 Released

    Type Hinting

    This documentation has moved to the function reference.

    User Contributed Notes

    Daniel dot L dot Wood at Gmail dot Com
    7 years ago
    People often ask about scalar/basic typehints.  Here is a drop in class that I use in my MVC framework that will enable typehints through the use of a custom error handler.

    Note: You should include this code above all other code in your include headers and if you are the using set_error_handler() function you should be aware that this uses it as well.  You may need to chain your set_error_handlers()

    Why?
    1) Because people are sick of using the is_* functions to validate parameters.
    2) Reduction of redundant coding for defensive coders.
    3) Functions/Methods are self defining/documenting as to required input.

    Also..
    Follow the discussion for typehints in PHP 6.0 on the PHP Internals boards.

    <?php

    define    ('TYPEHINT_PCRE'              ,'/^Argument (\d)+ passed to (?:(\w+)::)?(\w+)\(\) must be an instance of (\w+), (\w+) given/');

    class     Typehint
    {

        private static     $Typehints = array(
                'boolean'   => 'is_bool',
                'integer'   => 'is_int',
                'float'     => 'is_float',
                'string'    => 'is_string',
                'resrouce'  => 'is_resource'
            );

        private function     __Constrct() {}

        public static function     initializeHandler()
        {

                set_error_handler('Typehint::handleTypehint');

            return     TRUE;
        }

        private static function     getTypehintedArgument($ThBackTrace, $ThFunction, $ThArgIndex, &$ThArgValue)
        {

            foreach (    $ThBackTrace as $ThTrace)
            {

                    // Match the function; Note we could do more defensive error checking.
                    if (isset($ThTrace['function']) && $ThTrace['function'] == $ThFunction)
                {

                        $ThArgValue = $ThTrace['args'][$ThArgIndex - 1];

                    return     TRUE;
                }
            }

            return     FALSE;
        }

        public static function     handleTypehint($ErrLevel, $ErrMessage)
        {

            if (    $ErrLevel == E_RECOVERABLE_ERROR)
            {

                if (    preg_match(TYPEHINT_PCRE, $ErrMessage, $ErrMatches))
                {

                    list(    $ErrMatch, $ThArgIndex, $ThClass, $ThFunction, $ThHint, $ThType) = $ErrMatches;

                    if (isset(    self::$Typehints[$ThHint]))
                    {

                            $ThBacktrace = debug_backtrace();
                            $ThArgValue  = NULL;

                        if (    self::getTypehintedArgument($ThBacktrace, $ThFunction, $ThArgIndex, $ThArgValue))
                        {

                            if (    call_user_func(self::$Typehints[$ThHint], $ThArgValue))
                            {

                                return     TRUE;
                            }
                        }
                    }
                }
            }

            return     FALSE;
        }
    }

    Typehint::initializeHandler();

    ?>

    An are some examples of the class in use:

    <?php

    function teststring(string $string) { echo $string; }
    function     testinteger(integer $integer) { echo $integer; }
    function     testfloat(float $float) { echo $float; }

    // This will work for class methods as well.

    ?>

    You get the picture..
    michaelrfairhurst at gmail dot com
    3 years ago
    The scalar type hinting solutions are all overthinking it. I provided the optimized regex version, as well as the fastest implementation I've come up with, which just uses strpos. Then I benchmark both against the TypeHint class.

    <?php
    function optimized_strpos($ErrLevel, $ErrMessage) {
            if (    $ErrLevel == E_RECOVERABLE_ERROR
                    // order this according to what your app uses most
                    return strpos($ErrMessage, 'must be an instance of string, string')
                    ||     strpos($ErrMessage, 'must be an instance of integer, integer')
                    ||     strpos($ErrMessage, 'must be an instance of float, double')
                    ||     strpos($ErrMessage, 'must be an instance of boolean, boolean')
                    ||     strpos($ErrMessage, 'must be an instance of resource, resource');
    }

    function     optimized_regex($ErrLevel, $ErrMessage) {
            if (    $ErrLevel == E_RECOVERABLE_ERROR) {
                if(    preg_match('/^Argument \d+ passed to (?:\w+::)?\w+\(\) must be an instance of (\w+), (\w+) given/', $ErrMessage, $matches))
                    return     $matches[1] == ($matches[2] == 'double' ? 'float' : $matches[2]);
            }
    }
    ?>

    BENCHMARKING Typehint::handleTypehint()
    string type hint.....[function it(string $var) {}]............2.1588530540466 seconds
    float type hint......[function it(float $var) {}].............2.1563150882721 seconds
    integer type hint....[function it(integer $var) {}]...........2.1579530239105 seconds
    boolean type hint....[function it(boolean $var) {}]...........2.1590459346771 seconds

    BENCHMARKING optimized_regex()
    string type hint.....[function it(string $var) {}]............0.88872504234314 seconds
    float type hint......[function it(float $var) {}].............0.88528990745544 seconds
    integer type hint....[function it(integer $var) {}]...........0.89038777351379 seconds
    boolean type hint....[function it(boolean $var) {}]...........0.89061188697815 seconds

    BENCHMARKING optimized_strpos()
    string type hint.....[function it(string $var) {}]............0.52635812759399 seconds
    float type hint......[function it(float $var) {}].............0.74228310585022 seconds
    integer type hint....[function it(integer $var) {}]...........0.63721108436584 seconds
    boolean type hint....[function it(boolean $var) {}]...........0.8429491519928 seconds
    bantam at banime dot com
    7 years ago
    Daniel's typehint implementation was just what I was looking for but performance in production wasn't going to cut it. Calling a backtrace every time hurts performance. For my implementation I didn't use it, after all, PHP tells us what the data type is in the error message, I don't feel I need to evaluate the argument where I am using typehinting. Here is the cut down version I use in my error handling class:

    <?php
                public static function typehint($level, $message)
            {
                if(    $level == E_RECOVERABLE_ERROR)
                {
                    if(    preg_match('/^Argument (\d)+ passed to (?:(\w+)::)?(\w+)\(\) must be an instance of (\w+), (\w+) given/', $message, $match))
                    {
                        if(    $match[4] == $match[5])
                            return     true;
                    }
                }
               
                return     false;
            }
    ?>

    Hope this can be of use to somebody.
    kalkamar at web dot de
    7 years ago
    I really like the Daniel`s Typehinting-Class, but you please not that it may be relevant for the performance if you use Typehinting for scalar values very often.

    Here is my performance-test:

    <?php

    function notypehinting($x)
    {
            is_string($x);   //checking the type manually instead
    }

    function     typehinting(string $x)
    {
    }

    $test=new timer;
    for(    $i=0;$i<10000;$i++)
    {
    try{
            notypehinting('test');
    }
    catch(    Exception $e){}
    }
    echo     $test.'<br>';

    $test2=new timer;
    for(    $i=0;$i<10000;$i++)
    {
    try{
            typehinting('test');
    }
    catch(    Exception $e){}
    }
    echo     $test2.'<br>';
    ?>

    Output:

    0.0088460445404053
    0.21634602546692

    Result:
    typehinting() ist more than 20 times slower than notypehinting()

    You see: typehinting for scalar types (like suggested by Daniel) is not the best thing for the performance if you use it very often.
    jesdisciple @t gmail -dot- com
    8 years ago
    The manual's sample code says:
    <?php
    //...
    // Fatal Error: Argument 1 must not be null
    $myclass->test(null);
    //...
    ?>

    And this is true, unless a default value of NULL is given; in fact, this is the only way to give a default value for object arguments (as a default value must be a constant expression):
    <?php
    $mine     = new MyClass();
    $mine->test(NULL);
    class     MyClass{
        public function     __construct(OtherClass $arg = NULL){
            if(    is_null($arg)){
                    //Apply default value here.
                }
        }
        public function     test(array $arr = NULL){
                print_r($arr);
        }
    }
    class     OtherClass{
       
    }
    ?>
    Anonymous
    9 years ago
    The type hinting system can also be used for interfaces.  Example:

    <?php
    interface fooface
    {
        public function     foo ();
    }

    class     fooclass implements fooface
    {
        public function     foo ()
        {
            echo (    'foo<br>');
        }
    }
    class     barclass implements fooface
    {
        public function     foo ()
        {
            echo (    'bar<br>');
        }
    }
    class     bazclass implements fooface
    {
        public function     foo ()
        {
            echo (    'baz<br>');
        }
    }

    class     quuxclass
    {
        public function     foo ()
        {
            echo (    'quux<br>');
        }
    }

    function     callfoo (fooface $myClass)
    {
            $myClass -> foo ();
    }

    $myfoo = new fooclass;
    $mybar = new barclass;
    $mybaz = new bazclass;
    $myquux = new quuxclass;

    callfoo ($myfoo);
    callfoo ($mybar);
    callfoo ($mybaz);
    callfoo ($myquux); // Fails because the quuxclass doesn't implement the fooface interface
    ?>

    Using this syntax you can allow a function to work with different classes as long as they all implement the same interfaces.  An example might be an online shop that implements a plugin system for payment.  If the creator of the script provides a payment module interface then functions can check if it has been implemented in a given payment class.  This means that the details of the class are unimportant, so it doesn't matter if it interfaces with PayPal, HSBC, ProTX or any other payment system you care to name, but if it doesn't properly provide all the functionality a payment module requires a fatal error is generated. 

    Unfortunately, it doesn't seem possible to use type hinting with new.  In java you could do a "fooface myfoo = new fooclass" which would fail if you tried it with quuxclass instead, but as far as I can tell you can't do a similar test on create with PHP.
    john at cast dot com
    5 years ago
    i use eclipse ganymede as an IDE and it offers "intellisense" where it can, i.e. when variables are "declared" via type hinting or a "new"-statement . i found using the following pattern helps eclipse along as well:

    <?php
    class MyClass{

      public static function     Cast(MyClass &$object=NULL){
           return     $object;
      }

      public     method CallMe(){
      }
    }

    $x=unserialize($someContent);
    $x=MyObject::Cast($x);
    $x->CallMe();
    ?>

    after calling Cast(), due to the type hinting, eclipse offers me the "CallMe" function in a dropdown when i type "$x->" in the code afterwards.

    i found this very practical und included the Cast() function in my code template for new classes. i've been wondering, if there is a drawback i oversaw, but i haven't noticed any negative effects so far... maybe some of you will find this just as handy as i do ;o)

    p.s. do note: when used in inherited classes a STRICT-notice comes up, because the function definition of the inherited class doesn't match the parent's definition (different type hinting) - but it works great!
    nicholas at nicholaswilliams dot info
    9 years ago
    Please note that the following will not work:

    <?php

    abstract class Object
    {
        public abstract function     toString( );
        public abstract function     equals( Object &$o );
    }

    class     Chair extends Object
    {
        public function     toString( )
        {
            return     'This is a chair.';
        }
       
        public function     equals( Chair &$o )
        {
            return     TRUE;
        }
    }

    class     Table extends Object
    {
        public function     toString( )
        {
            return     'This is a table.';
        }
       
        public function     equals( Table &$o )
        {
            return     TRUE;
        }
    }

    $chair = new Chair();
    $table = new Table();

    echo     $chair->equals( $table );

    ?>

    The expected output is "Fatal error: Argument 1 passed to Chair::equals() must be an instance of Chair, called in [filename] on line 38 and defined in [filename] on line 16" but instead you get "Fatal error: Declaration of Chair::equals() must be compatible with that of Object::equals() in [filename] on line 20".

    This is unlike other OO languages (secifically Java) which not only allow but expect this type of code. It is in the nature of abstraction. However, you can get similar results using the following code instead:

    <?php

    abstract class Object
    {
        public abstract function     toString( );
        public abstract function     equals( self &$o );
    }

    class     Chair extends Object
    {
        public function     toString( )
        {
            return     'This is a chair.';
        }
       
        public function     equals( self &$o )
        {
            return     TRUE;
        }
    }

    class     Table extends Object
    {
        public function     toString( )
        {
            return     'This is a table.';
        }
       
        public function     equals( self &$o )
        {
            return     TRUE;
        }
    }

    $chair = new Chair();
    $table = new Table();

    echo     $chair->equals( $table );

    ?>

    This code gives the expected result "Fatal error: Argument 1 passed to Chair::equals() must be an instance of Chair, called in [filename] on line 38 and defined in [filename] on line 16". This is the proper behavior but isn't the most intuitive approach for those of us used to OO programming.

    Hope this helps someone :-).

    Nicholas
    ldebuyst->brutele.be
    9 years ago
    In reply to Nikivich and Edorian:

    Although it isn't quite clear from his post, I believe that the point nicholas is trying to make is that, if you typehint an abstract function, you MUST use that same typehint for all classes extending the abstract class.

    As his example shows, if you typehint (Object $object), then  you must use the exact same typehint in the extending class. Using the typehint (Table $table) or (Chair $chair) will give fatal errors, even if Table and Chair are subclasses of Object.

    In other words, type hinting allows for descendants, as caliban at darklock dot com has shown, except when you're subclassing.

    See http://bugs.php.net/bug.php?id=36601 for a bit more info. Flagged as wontfix, though, so something to keep in mind.
    sorin dot badea91 at gmail dot com
    3 years ago
    I've implemented a basic function to ensure argument's type.

    <?php
    /**
    * Primary types
    */
    class Type
    {
        const     SKIP     = 0;
        const     INT      = 1;
        const     STRING   = 2;
        const     BOOLEAN  = 3;
        const     CALLBACK = 4;
        const     FLOAT    = 5;
        const     RESOURCE = 6;
    }

    /**
    * @throws InvalidArgumentException
    */
    function ensureType()
    {
            $debugStack = debug_backtrace();
            $argv       = $debugStack[1]['args'];
            $types      = func_get_args();
        foreach (    $argv as $key => $value) {
                $message = null;
            if (    is_null($value)) {
                continue;
            }
            switch (    $types[$key]) {
                case     Type::INT:
                    if (!    is_int($value)) {
                            $message = 'Argument ' . $key . ' passed to ' . $debugStack[1]['function'] . '() must be of type int';
                    }
                    break;
                case     Type::STRING:
                    if (!    is_string($value)) {
                            $message = 'Argument ' . $key . ' passed to ' . $debugStack[1]['function'] . '() must be of type string';
                    }
                    break;
                case     Type::BOOLEAN:
                    if (!    is_bool($value)) {
                            $message = 'Argument ' . $key . ' passed to ' . $debugStack[1]['function'] . '() must be of type boolean';
                    }
                    break;
                case     Type::CALLBACK:
                    if (!    is_callable($value)) {
                            $message = 'Argument ' . $key . ' passed to ' . $debugStack[1]['function'] . '() must be a valid callback';
                    }
                    break;
                case     Type::FLOAT:
                    if (!    is_float($value)) {
                            $message = 'Argument ' . $key . ' passed to ' . $debugStack[1]['function'] . '() must be of type float';
                    }
                    break;
                case     Type::RESOURCE:
                    if (!    is_resource($value)) {
                            $message = 'Argument ' . $key . ' passed to ' . $debugStack[1]['function'] . '() must be of type resource';
                    }
                    break;
            }
            if (!    is_null($message)) {
                if (    is_object($value)) {
                        $message .= ', instance of ' . get_class($value) . ' given';
                } else {
                        $message .= ', ' . gettype($value) . ' given';
                }
                throw new     InvalidArgumentException($message);
            }
        }
    }

    function     dummyFunction($var1, $var2, $var3)
    {
            ensureType(Type::BOOLEAN, Type::INT, Type::STRING);
    }

    $object = new ReflectionClass('ReflectionClass');

    dummyFunction(1, $object, 'Hello there');
    dpariyskiy at netatwork dot com
    6 years ago
    Daniel, thank you for the type hinting class. Very useful.
    For anyone having a problem where php isn't setting Daniel's error handler, as was the case for me, try changing initializeHandler function to the following:

    <?php
    public static function initializeHandler()
    {
       
            set_error_handler(array('Typehint','handleTypehint'));
       
        return     TRUE;
    }
    ?>

    Hope this helps,
    --Dmitriy
    wickedmuso at gmail dot com
    7 years ago
    One useful thing with Type Hinting that I could not find in the documentation (but tested) is that you can also use an Interface in the hint (versus a Class).  This is a very useful tool if you are trying to code to Interfaces rather than Classes (which is common in Test Driven Development and Dependency Injection paradigms).  It means your external class can present itself into the method as long as it implements the nominated Interface (obviously).
    mlovett at morpace dot com
    10 years ago
    Type hinting works with interfaces too. In other words, you can specify the name of an interface for a function parameter, and the object passed in must implement that interface, or else type hinting throws an exception.
    marcus at ignorethis netweblogic dot com
    7 years ago
    Love the typehint object Daniel. Great effort!

    However, it still throws catchable fatal errors, which is not what I want, so I added one line to handleTypehint() so it throws an Exception.

    <?php
    public static function handleTypehint($ErrLevel, $ErrMessage) {
            if (    $ErrLevel == E_RECOVERABLE_ERROR) {
                if (    preg_match ( TYPEHINT_PCRE, $ErrMessage, $ErrMatches )) {
                    list (     $ErrMatch, $ThArgIndex, $ThClass, $ThFunction, $ThHint, $ThType ) = $ErrMatches;
                    if (isset (     self::$Typehints [$ThHint] )) {
                            $ThBacktrace = debug_backtrace ();
                            $ThArgValue = NULL;
                        if (    self::getTypehintedArgument ( $ThBacktrace, $ThFunction, $ThArgIndex, $ThArgValue )) {
                            if (    call_user_func ( self::$Typehints [$ThHint], $ThArgValue )) {
                                return     TRUE;
                            }
                        }
                    }
                    throw new     Exception($ErrMessage);
                }
            }
            return     FALSE;
        }
    ?>
    doom at doom dot pl
    2 years ago
    I've done some tests of the overhead that class Typehint  gives us.
    At my PC it goes as follows:
    teststringNormal took: 0.041965961456299
    teststringOverhead took: 0.48374915122986
    It's like 10x longer time (not mention about memory usage), it's just because exception is thrown EVERY SINGLE TIME, along with expensive preg_match() and debug_backtrace() calls.
    I think that using class in bigger applications will increase overhead like 100% or more.
    <?php

    function teststringOverhead(string $string) {
        return     $string;
    }
    function     teststringNormal($string){
        if(!    is_string($string)){
            return;
        }
        return     $string;
    }
    $loopTimes = 20000;

    /////////// test of overhead implementation vs normal
    $t1 = microtime(true);
    for(    $i = 0; $i <= $loopTimes; $i++)  teststringNormal("xxx");
    echo     "<br>teststringNormal took: " . (microtime(true) - $t1);

    $t2 = microtime(true);
    for(    $i = 0; $i <= $loopTimes; $i++)  teststringOverhead("xxx");
    echo     "<br>teststringOverhead took: " . (microtime(true) - $t2);
    ?>
    mrice at rcs dot us
    12 days ago
    In regards to http://php.net/manual/en/language.oop5.typehinting.php#103729 , when using PHP in Eclipse, the best way to typehint is already available in Eclipse natively.

    The format is /* @var $variable ObjectName */

    The single /* is important. You can also use namespaces, IE

    /* @var $variable \Some\Namespace */

    In short, there is no reason to create functions that return itself.
    Anonymous
    8 months ago
    i think this is pretty close.

    $lines=hhb_mustbe('array',file("foofile"));
    //either file succeeds, and returns an array, or file returns FALSE which is not an array, which throws an unexpectedValueException.

    $socket=hhb_mustbe('Socket',socket_create(AF_INET,SOCK_STREAM,getprotobyname('tcp')));
    //either socket_create succeeds, and returns a Socket, or socket_create returns False, which is not a resource of type Socket, and you get an UnexpectedValueException

    $size=hhb_mustbe('int',filesize(somefile));
    //either filesize() returns an integer, or returns FALSE wich is not an int, and you'll get UnexpectedValueException.

        function hhb_mustbe(/*string*/$type,/*mixed*/$variable){
            //should it be UnexpectedValueException or InvalidArgumentException?
            //going with UnexpectedValueException for now...
            $actual_type=gettype($variable);
            if($actual_type==='unknown type'){
                //i dont know how this can happen, but it is documented as a possible return value of gettype...
                throw new Exception('could not determine the type of the variable!');
            }
            if($actual_type==='object'){
                if(!is_a($variable,$type)){
                    $dbg=get_class($variable);
                    throw new UnexpectedValueException('variable is an object which does NOT implement class: '.$type.'. it is of class: '.$dbg);
                }
                return $variable;
            }
            if($actual_type==='resource'){
                $dbg=get_resource_type($variable);
                if($dbg!==$type){
                    throw new UnexpectedValueException('variable is a resource, which is NOT of type: '.$type.'. it is of type: '.$dbg);
                }
                return $variable;
            }
            //now a few special cases
            if($type==='bool'){
                $parsed_type='boolean';   
                } else if($type==='int'){
                $parsed_type='integer';
                } else if($type==='float'){
                $parsed_type='double';
                } else if($type==='null'){
                $parsed_type='NULL';
                } else{
                $parsed_type=$type;
            }
            if($parsed_type!==$actual_type && $type!==$actual_type){
                throw new UnexpectedValueException('variable is NOT of type: '.$type.'. it is of type: '.$actual_type);
            }
            //ok, variable passed all tests.
            return $variable;
        }
    gdecad at NOSPAM dot example dot com
    5 years ago
    I have made a little bench between three method of type hinting for native type (string, integer, ...).

    First method : by test type in function like :
    <?php
    function testTest($arg) {
        if (!    is_string($arg)) {
                trigger_error('Argument $arg passed to test must be an instance of string, other given');
        }
        return     $arg;
    }
    ?>

    Second method : by object representing native type :
    <?php
    function testObject(StringObj $arg) {
        return     $arg;
    }
    ?>

    Third method : by class TypeHint proposed by Daniel :
    <?php
    function testHint(string $arg) {
        return     $arg;
    }
    ?>

    the results are here :
    bench for 100000 iterations,  in seconds
            avg                    min                    max                    total
    test    5.3275489807129E-6    2.8610229492188E-6    0.0033020973205566    0.53275895118713
    object    4.9089097976685E-6    3.814697265625E-6    0.0025870800018311    0.49089503288269
    hint    3.2338891029358E-5    2.9802322387695E-5    0.0025920867919922    3.2338931560516

    As you can see, the method by object is the best
    now you know...
    Nikivich
    9 years ago
    In reply to Nicolas

    I don't think you exactly understand the inheritance principles
    If you want to do the equals thing in a decent OO way, you would do something like this:

    class Object {
          public equals(Object &o) {
                return this == &o; //perform default equals check, one could arguably say that === is the correct default, but doesnt matter for the example
          }
    }

    class Chair extends Object {
    }
    class Table extends Object {
    }

    $chair = new Chair();
    $table = new Table();
    $chair->equals($table); //will print false (zero)

    This is actually a correct implementation of an equals method. Since you want to take a chair for example and just call equals() on it WITH ANY OBJECT, you should only hint Object, not an implementation, since the whole point of the equals method is to find out whether it is actually the same object :-) I want to be able to pass a table (which implements Object too, so is perfectly allowed as a parameter to equals).

    Hope this clears it up a bit for you... :-)
    Edorian
    9 years ago
    In response to nicholas at nicholaswilliams dot info:

    Of course this doesn't work. Not in Php nor in Java.

    You can't put a Chair into Table just because there both implementing "Object"

    It wouldn't make any sense to say "i'm expecting an argument that implements the same object that i'm implementing" with type hinting.

    You say: "I'm expection an Object of that Class or a Object of a Subclass of that Class " like you do in every OO languange.
    Anonymous
    5 years ago
    Please note, there is a strong typing in PHP.

    You have to import one PHP library to your existing projects, and create some classes, in which the scalar values will be automatically wrapped by an autoboxing mechanism known from Java, like so:

    <?php
    class String extends AutoBoxedObject
    {
        public     $value;

        public function     __construct($value) {
                $this->value = $value;
        }

        public function     __toString() {
            return     "$this->value";
        }

        public function     toUpperCase() {
            return     strtoupper($this->value);
        }
    }

    function &     string($value = null) {
            $x = & VariablesManager::getNewPointer(new String($value));
        return     $x;
    }
    ?>

    From now on you can declare the type of data in your variables, and validate their values in a class constructor.

    See this example:

    <?php
    $y     = & string("aaa");
    // lets check, that $y is an object
    var_dump($y);

    // now we are overwritting $y variable with a scalar value of "zzz"
    $y = "zzz";
    // var_dump() shows us, that "zzz" is still an object, not the scalar type as in regular PHP
    var_dump($y);
    // the line below should raise a fatal error, because "zzz" was a scalar type (string), but it will be ok, because $y is still an object (thanks to autoboxing)
    var_dump($y->toUpperCase());
    ?>
    Now, the output is:

    object(String)#1 (2) {
      ["value"]=>
      string(3) "aaa"
      ["ref":protected]=>
      int(1)
    }
    object(String)#2 (2) {
      ["value"]=>
      string(3) "zzz"
      ["ref":protected]=>
      int(1)
    }
    string(3) "ZZZ"

    As you can see, PHP can be as good as Java or C#:)

    To enforce strong data types you just have to do it in the wrapper class, like so:
    <?php
    class Integer extends AutoBoxedObject
    {
        public     $value;

        public function     __construct($value) {
            if(!    is_int($value)) { throw new Exception("Invalid data type"); }
                $this->value = $value;
        }

        public function     getValue() {
            return     $this->value;
        }

        public function     __toString() {
            return (string)    $this->value;
        }
    }
    ?>

    To download the library, just google for 'strong data typing autoboxing' . There is an article describing how to use it, and a download link to the appropriate PHP library.
    macobex dot exe at gmail dot com
    5 years ago
    I agree [that] using object/wrapper is faster than using the is_* functions.

    But I think we must also consider the fact that when we pass an argument to a function, most likely we will use it's value. So I've done a little test to see which approach is faster.

    Primitive Approach:
    <?php

    function testPrimitive($str) {
       if (     is_string($str) )
              $x = $str . ' world';   // using the argument's value
           else
              trigger_error('Argument passed must be of type string.');
       }

    ?>

    Wrapper Approach:

    <?php

           function testWrapper(StringWrapper $str) {
              $x = $str->getValue() . ' world';  // using the argument's value
           }

    ?>

    Test: 10,000 iterations
    Results:
       primitive average: 0.026113033294678
       wrapper average: 0.063039064407349

       primitive is faster than wrapper approach by 41.42357368431%

    Using the is_* function is faster than using wrapper class, given the fact that we just not want to check the type of the argument, but we also want to use the value of the argument.
    DanielLWood [at] Gmail [dot] Com
    7 years ago
    To follow up on my original post dealing with the type hinting class I provided:

    Kalkamar is absolutely correct, it is slow and is a hack.  Everyone who uses it and wants to see this type of syntax native needs to post on the 'php internals' development thread in support.

    Thanks,

    Dan
    alejosimon at gmail dot com
    5 years ago
    For PHP 5.3 version and namespaces support.

    <?php

    function phpErrorHandler( $code, $message, $file, $line ) {

        if (     error_reporting() & $code ) {

            if (     $code == E_RECOVERABLE_ERROR ) { // Scalar Type-Hinting patch.

                    $regexp = '/^Argument (\d)+ passed to (.+) must be an instance of (?<hint>.+), (?<given>.+) given/i' ;

                if (     preg_match( $regexp, $message, $match ) ) {

                        $given = $match[ 'given' ] ;
                        $hint  = end( explode( '\\', $match[ 'hint' ] ) ) ; // namespaces support.

                        if ( $hint == $given ) return true ;
                }
            }

            return     false ;
        }
    }

    set_error_handler( 'phpErrorHandler' ) ;

    /************************************/

    function typeHintTest( integer $arg1 ) {

            print_r( $arg1 ) ;
    }

    typeHintTest( true ) ; // Error throw because not integer type.

    ?>
    info at thewebsiteguy dot com dot au
    7 years ago
    I find it rather frustrating that PHP has internal data types but doesn't allow optional hinting for it.  I REALLY needed it for something, so I found a way around it.

    <?php
    abstract class DataType
    {
        protected     $length;
        protected     $precision;
        protected     $number;
       
      public function     __construct()
      {
            $this->number = false;
            $this->precision = null;
      }
       
        public function     GetLength()
        {
            return     $this->length;
        }
       
        public function     IsNumber()
        {
            return     $this->number;
        }

        public function     GetPrecision()
        {
            return     $this->precision;
        }
    }

    class     Integer extends DataType
    {
        public function     __construct($length = 12)
        {
                parent::__construct();
                $this->number = true;
                $this->length = $length;
                $this->precision = 0;
        }
    }

    class     Float extends DataType
    {
      public function     __construct($length = 12, $precision = 2)
      {
            parent::__construct();
            $this->number = true;
            $this->length = $length;
            $this->precision = $precision;
      }
    }

    class     String extends DataType
    {
        public function     __construct($length = 255)
        {
                parent::__constructor();
                $this->length = $length;
        }
    }
    //etc etc through the types...
    ?>

    then later I can do this...

    <?php
    final class Field
    {
        public     $Name;
        public     $Mandatory;
        public     $Hidden;
        public     $ListField;
        public     $Value;
        public     $ForeignClass;
        public     $ReadOnly;
        public     $DataType;
       
        public function     __construct($name, DataType $dataType, $mandatory = false, $listField = true, $value = null, $readOnly = false, BaseCBO $foreignClass = null)
        {
                $this->Name = $name;
                $this->DataType = $dataType;
                $this->Mandatory = $mandatory;
                $this->ListField = $listField;
                $this->Value = $value;
                $this->ReadOnly = $readOnly;
                $this->ForeignClass = $foreignClass;
        }
    }

    // ....

    class DoSomeStuff
    {
        public function     DoGenericThings(Field $field)
        {
            if (    $field->DataType instanceof Integer)
            {
                    // do things for an integer field...
                }
        }
    }
    ?>
    Jazz
    8 years ago
    To Nikivich and Edorian:

    There are many times when you would use an equals() method other than to find out if the two objects are the same object. Think of all the primitive wrapper classes in Java, for example -- if you create two new Integer()'s with identical values, equals() returns true, even though they are two different objects. There would be no reason to allow someone to perform an equals() between an Integer and, say, a GregorianCalendar -- it just doesn't make sense. In Java you would attempt this and probably get a ClassCastException, but in PHP no such facility exists, so the best way to prevent this would be through type hinting.

    The point Nicholas was making is that you can't specify a stricter type hint on an inherited method, and despite your arguments, that would be a truly useful thing to be able to do.

    (True overloading would be a better way, IMHO, but *shrug*)
    wbcarts at juno dot com
    7 years ago
    TYPE-HINTING and VISIBILITY

    Type-hinting is just one more small piece of PHP that protects our objects when visibility cannot.

    <?php

    class Point {
      public     $x, $y;

      public function     __construct($xVal = 0, $yVal = 0) {
            $this->x = $xVal;
            $this->y = $yVal;
      }
    }

    class     Polyline {
      protected     $points = array();

      public function     addPoint(Point $p) {  // the line we're interested in...
            $this->points[] = $p;
      }
    }

    $point1 = new Point(15, 12);
    $polyline = new Polyline();
    $polyline->addPoint($point1);
    $polyline->addPoint(new Point(55, 22));
    $polyline->addPoint(new Point(33, 31));

    $polyline->addPoint(new stdClass());    // PHP will throw an error for us! 

    ?>

    Since our Polyline::addPoint() function has to be public, any outside code can try to pass anything. But, when type-hinting is declared, PHP throws an error when phoney data tries to sneak by.
    comments at ignorethis netweblogic com
    7 years ago
    Note that you cannot add a type hint and give a default value, apart from arrays. You will get an internal server error, or fatal error.

    e.g.

    <?php

    //Wont work
    function test(ObjName $obj = ''){
           //.....
    }

    //Will work
    function test(Array $obj = array()){
           //.....
    }

    ?>

    Even if you have Daniel's implementation of type hinting, a string typehint will still not work if you give it an empty string default too.
    madness
    7 years ago
    I must admit that Daniel's implementation is quite awesome (after all we'd be omonyms if I was english, omen nomen ;-) ), for everyone that already has a function/class to handle errors, this is a quick method to integrate the TypeHint class:

    <?php
            public static function handleError($errno, $errstr, $errfile, $errline){

                // Implements just-in-time classes for broad type hinting
                if (TypeHint::handleTypehint($errno, $errstr)){
                return     true;
            }
           
                // do your usual stuff here
            /*
             * ...
             */
            }
    ?>

    The initializeHandler method and the Typehint::initializeHandler(); call are rendered useless in this case. Enjoy.
    reinier dot kip at gmail dot com
    6 years ago
    Please note that when using the type hinting class together with namespaces, you're asking for trouble:

    <?php
    namespace a {
        interface     A {
            public function     execute(string $sth);
        }
    }

    namespace     a\b {
        class     B implements a\A {
            public function     execute(string $sth){} // Wrong
                public function execute(a\string $sth){} // Correct
            }
    }     // Causes a fatal error on this line. 'string' is considered an object from the namespace 'a'
    ?>
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