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Date: Thu, 26 Feb 2015 15:24:18 +0400
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To: Benjamin Eberlei <kontakt@beberlei.de>
Cc: Anthony Ferrara <ircmaxell@gmail.com>, PHP Internals <internals@lists.php.net>
Content-Type: multipart/alternative; boundary=047d7b86d990273cc6050ffbfe23
Subject: Re: [PHP-DEV] Strict typing and callback vs declare()
From: dmitry@zend.com (Dmitry Stogov)

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On Thu, Feb 26, 2015 at 2:09 PM, Benjamin Eberlei <kontakt@beberlei.de>
wrote:

>
>
> On Thu, Feb 26, 2015 at 11:56 AM, Dmitry Stogov <dmitry@zend.com> wrote:
>
>>
>>
>> On Thu, Feb 26, 2015 at 1:34 PM, Benjamin Eberlei <kontakt@beberlei.de>
>> wrote:
>>
>>>
>>>
>>> On Thu, Feb 26, 2015 at 11:10 AM, Dmitry Stogov <dmitry@zend.com> wrote:
>>>
>>>> Hi Anthony,
>>>>
>>>> What do you think about using a user level callback for strict type
>>>> checks
>>>> instead of declare(). It won't allow changing behavior per file, but
>>>> this
>>>> has its own cons and pros.
>>>>
>>>> <?php
>>>> set_strict_type_checker(function ($class_name, $function_nume, $arg_num,
>>>> $expected_type, $value, $file, $line) {
>>>>   ...
>>>>   return false;
>>>> });
>>>> include("orig_index.php");
>>>> ?>
>>>>
>>>> If callback is not set, arguments are converted according to standard
>>>> rules, if set and returns false - fatal error or exception is thrown.
>>>>
>>>> The implementation should be simpler and more efficient than using
>>>> declare().
>>>>
>>>> Thanks. Dmitry.
>>>>
>>>
>>> This ruins portability with third party libraries completely.
>>>
>>
>> Not completely, because checker may be smart enough to return "true" for
>> third party files.
>>
>> <?php
>> set_strict_type_checker(function ($class_name, $function_nume,
>> $arg_num,$expected_type, $value, $file, $line) {
>>    if (!my_own_file($filename)) {
>>      return true;
>>    }
>>    ...
>>    return false;
>> });
>> include("index.php");
>> ?>
>>
>> And you won't have to modify each file in your project adding
>> declare(strict_types=1).
>>
>
> Yes, but you need a mechanism for each third party library to register
> their typechecker code and then build a generic type checker system using
> the right checks for the right library. This will produce really slow code
> considering it will trigger this on every argument.
>

Only for strictly wrong arguments.


> Also i find declare(strict_types=1) is already adding another stack in my
> mind to think about, now having to think about every file/lirary having a
> different kind of validation makes it even more complicated.
>

You 'll have to think about each file anyway. To add or not to add
declare(strict_types=1).
Callback would allow to care about strict type checks in one separate place.
It's like to keep a screw key with every nut in your car instead of keeping
toolbox.


>
> Additionally it destroys the AOT compile benefit of static type hints,
> since you cannot compile code down to C again, because the
> conversion/validation is not necesarily deterministic.
>

Oh god...
If you know the type of passed and expected argument at compile time,
strictness doesn't make any difference (you may only report a error at
compile time).
If you don't know type of passed or expected argument at compile time,
you'll have to check their equality at run-time anyway.

Thanks. Dmitry.


>
>
>>
>> Thanks. Dmitry.
>>
>>
>>
>

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