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Date: Wed, 1 Jul 2009 22:36:46 +0100
Message-ID: <af54caaf0907011436g4fb119f3p929b79670d26abd7@mail.gmail.com>
To: Hannes Magnusson <hannes.magnusson@gmail.com>
Cc: Stanislav Malyshev <stas@zend.com>, Ilia Alshanetsky <ilia@prohost.org>, 
	PHP internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] RFC: Type hinting revisited for PHP 5.3
From: paul.biggar@gmail.com (Paul Biggar)

On Wed, Jul 1, 2009 at 10:23 PM, Hannes
Magnusson<hannes.magnusson@gmail.com> wrote:
> On Wed, Jul 1, 2009 at 23:07, Paul Biggar<paul.biggar@gmail.com> wrote:
>> So, what you're saying is, the patch already handles coercion? If
>> that's the case, then problem solved.
>
> The patch offers scalar type _hinting_. Not type _casting_.
>
> Type hinting in PHP works very simply: If the value doesn't type-match
> the argument information (arginfo internally) then it will be rejected
> and E_RECOVERABLE_ERROR thrown.
>
> In most circumstances that error is fatal. However. If the user
> chooses then he can ignore that error (by creating his own error
> handler) and continue the execution.
>
> Type _hinting_ is in no way related to type _casting_.


It should be.

The current type hinting is for objects, which in PHP are strongly
typed. We plan to extend it to scalars, which in PHP are weakly typed.
Adding a strong type system for scalars goes against the rest of the
language.

As Stas said:
> With this patch, we won't have one logic anymore - we'd have two logics - one for typehinted functions (reject everything that doesn't match the type) and one for the rest of the language (try to coerce
> types). Two logics in one language is usually not good.

PHP already has 2 type systems. I don't think that adding a 3rd one is
complementary.



> Furthermore, the patch introduces couple of new types, "scalar" and
> "numeric". These are "magic types" and do value-to-real-type
> comparison. No type casting.
> The scalar type hint accepts strings, booleans, ints and floats.
> The numeric type hint accepts strings (that pass is_numeric()),
> booleans, ints and floats.


Yes. Therefore only the scalar and numeric types are useful. Nobody
wants to use an 'int' hint that fails on numeric strings.

Also, I don't know what happens for string hints when you pass an
object with a __toString handler, but it should be allowed.


Thanks,
Paul

-- 
Paul Biggar
paul.biggar@gmail.com