Typehints for scalar types

Saturday, June 17th 2006, 16:03 CEST

Sandefjord, Norway

An attendee at the PHP New York Conference asked me on some tips on how to implement typehinting for scalar types (integer, float, string, boolean...). In about 20 minutes I explained how it could be done, but I got a bit bored at my flight back so I finished the patch already. The patch is most likely not the best way of implementing this either, and I am also not sure if this patch should be applied to PHP's CVS at all. It might be useful for people that have more control over their PHP setup so I decided to publish it here instead.

Besides the four scalar types it also allows the "object" type hint which will allow objects of any class to be passed. A small example is here:

<?php
class blah {
}
function foo1( object $a )
{
}
$b = new blah;
foo1( $b );
function foo2( integer $i, float $f, bool $b )
{
}
foo2( 'string', 42, 49.9 );

The example above should show:

Catchable fatal error: Argument 1 passed to foo2() must be of type integer, string given, called in /tmp/test.php on line 16 and defined in /tmp/test.php on line 12

Shortlink

This article has a short URL available: https://drck.me/tfst-4ti

Comments

Ben Ramsey

Saturday, June 17th 2006, 18:03 UTC

Will it dynamically cast the string "42" as the int 42?

Sebastian

Saturday, June 17th 2006, 18:14 UTC

I would love to see this in PHP 6!

Evert

Saturday, June 17th 2006, 18:44 UTC

Very cool! Sadly i can't really use it if it isnt either PECL or in PHP.. :(

Btw, is the 'object' typehint really needed? STDClass will also work..

Mike

Sunday, June 18th 2006, 10:23 UTC

I'm of course against it being applied, except the general object typehint, which is useful.

rami

Sunday, June 18th 2006, 13:31 UTC

I don't think so. It might raise a fatal error.

Hans

Sunday, June 18th 2006, 15:53 UTC

> Btw, is the 'object' typehint really needed? STDClass will also work..

class Foo{} $f = new Foo(); var_dump(($f instanceof StdClass));

result: bool(false)

If you thought StdClass was to PHP what java.lang.Object was to Java, you would be wrong.

I'm sure that Nietzsche would love OO PHP. It is his veiled woman, something completely different on the outside than the inside, always eluding comprehension, always just out of reach. :)

Derick

Sunday, June 18th 2006, 21:13 UTC

@Hans: StdClass will not work... not all classes inherit from this one in PHP.

@Ben: No, it doesn't cast... the idea of type hints is to prevent wrong data from being passed. It is up to the calling function to provide the correct type.

Daniel

Monday, June 19th 2006, 07:35 UTC

This patch sounds great. Hope it will be be a regular part of the Engine soon...

By the way I've started to implement a string-class as an extension for php, now i can stop doing this because there is my string typehint :)

Regards

judas_iscariote

Monday, June 19th 2006, 19:32 UTC

I hope this can be included in PHP6. I think it's a great new feature.

pcdinh

Friday, June 23rd 2006, 12:27 UTC

I love it. It should be incorporated into upcoming PHP 5.2

Les

Wednesday, July 5th 2006, 19:42 UTC

nope, i'm not convinced that this would work, nor that we actually need it in the first place.

sorry, but you should have found something else to do with your 20 minutes ;)

isao

Saturday, August 19th 2006, 20:49 UTC

i think this would be great, please add this to PHP!

text/int/float automatically get coerced anyway, but the the type hints would at least improve code readability without developers resorting to Hungarian notation.

type hinting for array and object parameters would provide a definite benefit.

it would be very useful for a function to throw an error if a parameter that should be an array is actually a string. this kind of thing can easily slip by (count/sizeof accept strings iirc) unnoticed for a while. rather than always use is_array(), why not just type hint it, and save everyone redundant code and improve clarity?

Evert

Monday, October 30th 2006, 03:06 UTC

Would love to see this in PHP6

thomas

Friday, November 10th 2006, 16:04 UTC

array type hinting was introduced with PHP 5.1 (see http://www.php.net/manual/en/language.oop5.typehinting.php)

sam b

Thursday, November 15th 2007, 06:00 UTC

This is great, thanks alot. I've been waiting for this for quite a while, I was actually working on my own patch when I found this, but compared to yours mine was very bad.

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