One of the features included in the PHP 5.x releases is type hinting for validating that you have the right values for your functions and methods coming in. In this new post to his blog Ilia Alshanetshy takes a look at the the feature and gives a patch to add it .

On a general level most people agree it would be a good idea to have, since it is an optional feature and does not introduce any regressions, heck you can even mix type hinted code with the non-type hinted one. The "PROBLEM" has always been combining of PHP's typeless nature with type hinting, which is where the consensus has been difficult (impossible) to reach.

He mentions an example of why its such an issue (technically, both 1 and "1" are valid numbers) and includes a link to a patch that gives a new hint to help with the problem.

On the PHP in Action blog, there's a new post looking at a recent library that was posted to support type hinting on scalars. They agree with his choice of subjects, noting that they see type hinting as much more useful on scalars than on objects.

I admit that these judgments are hard to make. I could be wrong, more or less. Type hints are probably useful when code becomes stable enough and at the boundaries between modules. But I still tend to avoid using them until I get an actual bug that might have been prevented by a type hint. Their usefulness is and has to be an empirical question. The purpose of using them has to be catching errors earlier, so if they don't have that effect, there's no point.

He lists three reasons why he had given up on type hinting before, one being the limited usefulness when it came to objects. Applying it to scalars is a different matter, though, and can prevent improper passing of array/scalars when the other is needed.

Derick Rethans has two blog posts for us today, the first details a patch he created which allows us to use type hints for all variable types in PHP.

Derick himself admits that its probably not the best approach:

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.

He offers the following as an example of how this would be used:

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

Derick also posted his Database Design Slides from his talk earlier this year at php|architects php|tek