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Date: Thu, 5 Feb 2015 17:07:21 +0400
Message-ID: <CA+9eiLuAhPDb_a4TJfmwhhbsq1CnVeEVEF+avQ=8gnWdGKyhAA@mail.gmail.com>
To: Alexander Lisachenko <lisachenko.it@gmail.com>
Cc: Patrick Schaaf <php@bof.de>, PHP internals list <internals@lists.php.net>, 
	Yasuo Ohgaki <yohgaki@ohgaki.net>
Content-Type: multipart/alternative; boundary=001a1135f1ce0b15e2050e56fcd7
Subject: Re: [PHP-DEV] Design by Contract
From: dmitry@zend.com (Dmitry Stogov)

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At this moment, I don't have any plans related to implementation of
hook-able compiler.
However the first step was already done, introducing "zend_ast_process"
callback.
In general it's should be possible to provide PHP API to manipulate with
AST and write compiler extensions in PHP.
Looks promising.. :)
Anyway, If you are interested - start working on it.

Thanks. Dmitry.



On Thu, Feb 5, 2015 at 3:42 PM, Alexander Lisachenko <
lisachenko.it@gmail.com> wrote:

>
> 2015-02-05 15:32 GMT+03:00 Dmitry Stogov <dmitry@zend.com>:
>
>> Hi Alexander,
>>
>> Defining contracts through doc-comments is also possible, but this way is
>> not native.
>> On the other hand, if you already have this implemented, we may just
>> reuse it.
>>
>
>
> Thanks, Dmitry! This would be a really nice feature on engine-level.
> Ideally, for PHP7-8, I would like to see a hook system from compile-level
> to userland, to define a language extension. This feature is highly
> required for custom DSLs and much more. DbC technique can be also
> implemented as parse-time weaver. E.g. we define a parser-extension:
>
> register_parser_extension(ContractExtension::class);
>
> this class will receive an AST of PHP file and check interesting nodes.
> This node can be annotation or something else:
>
> [Contract::Invariant => $this->value > 0]
> class Test {
>     public $value = 100;
>     public function foo($newValue) {
>         $this->value = $newValue;
>     }
> }
>
> and parser extension change the compiled source code by inserting this
> check into methods:
>
> [Contract::Invariant => $this->value > 0]
> class Test {
>     public $value = 100;
>     public function foo($newValue) {
>         $this->value = $newValue;
>         assert($this->value > 0); // Inserted by parser extension (via
> opcodes)
>     }
> }
>
> Is it possible to do this?
>

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