Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:71719
Mailing-List: contact internals-help@lists.php.net; run by ezmlm
Received-SPF: error (pb1.pair.com: domain hoa-project.net from 95.130.10.56 cause and error)
Message-ID: <52E8C04E.1090609@hoa-project.net>
Date: Wed, 29 Jan 2014 09:48:14 +0100
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9; rv:28.0) Gecko/20100101 Thunderbird/28.0a2
MIME-Version: 1.0
To: internals@lists.php.net
References: <CAGa2bXa+VdBP+eDmGLYSX+94+fHfmAqASA_3aZOj_JrAVg1fgw@mail.gmail.com>
In-Reply-To: <CAGa2bXa+VdBP+eDmGLYSX+94+fHfmAqASA_3aZOj_JrAVg1fgw@mail.gmail.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: quoted-printable
Subject: Re: [PHP-DEV] DbC for PHP?
From: ivan.enderlin@hoa-project.net ("Ivan Enderlin @ Hoa")

On 28/01/2014 08:05, Yasuo Ohgaki wrote:
> Hi all,
Hello :-),


> I'm wandering if we could have DbC (Design by Contract) for PHP 6.
> http://en.wikipedia.org/wiki/Design_by_contract
>
> There is user land implementation already.
> https://gitorious.org/higher-order-php/php-contracts/source/5b0a53b9732=
f0e4dbe79345212c84c74526def3b:
>
> It could be done with dbc mode INI switch as follows.
>
> When dbc=3Don, automatically includes
>
> include __dbc_ . __SCRIPT_NAME__;
>
>   when a script is loaded. No error if there is not the script.
> When function/method is called
>
> __dbc_pre_. __FUNCTION__() is called before calling function().
> __dbc_post_.___FUNCTION__() is called after function() call.
>
> No error if there is not the function.
What kind of errord would you like to print? =E2=80=9CThe precondition ha=
s=20
failed=E2=80=9D, ok but why? With what data?


> Class methods would be more complex, but basic idea is the same.
> Issue would be what we should do with $this with class methods.
>
> Automatic namespace might be nice to have for both function and class.
>
> When dbc=3Doff, these would be skipped at all.
>
> It does not sacrifice performance at all for production while it could =
catch
> various errors during development. It could do more complex assertion
> than assert()
So the pre- and postconditions must be predicates, i.e. computing a boole=
an.


> and it could check post condition that is difficult to achieve
> by assert(). User could have their own strong type safety as long as th=
ey
> have strict input validation. It could be used as complement of annotat=
ion.
>
> Just an idea.
> Any comments?
What about invariants which is the third part of DbC?


Did you heard about Praspel [1]. Praspel is a BISL (Behavioral Interface =

Specification Language), i.e. a specification language for=20
contract-based testing I develop in my PhD thesis (in INRIA=20
laboratories). You will find some materials here [2]. I recommend you to =

start by the presentations/keynotes. The idea is to allow the user to=20
write contracts (precondition, postcondition, exceptional postcondition, =

invariant, behavior etc.), and we exploit them in order to generate=20
(unit) tests automatically.

I'm reaching the end of my PhD and I'm currently writing the=20
documentation and finalizing the tools. Today, we are able to:
     (1) generate very different kinds of data (strings with regexs or=20
grammars thanks to grammar-based testing algorithms [3, 4], arrays=20
thanks to an array-solver [5] etc.)
     (2) verify a contract with a Runtime Assertion Checker (please, see =

articles or directly the code [6])
     (3) automatically generate (unit) tests that are executable with=20
atoum's API [7, 8]

We are preparing videos and documentations in order to promote it up to=20
June. I suggest to read the presentations, you will get an overview of=20
all the work.

I think DbC must stay annotations, so in comments of the code. If=20
contracts would be part of the PHP grammar, it would be disappointed for =

everyone because there is no unique way to express a contract: either=20
with the language syntax itself (such as JML [9]) or with a dedicated=20
language, such as Praspel. Both have pros and cons that I won't describe =

here (except if you ask).
However, having the Aspect Oriented Programming paradigm would be very=20
appreciated. It would avoid a lot of instrumentations and static analyzes=
=2E


Regards.

[1] https://en.wikipedia.org/wiki/Praspel
[2] http://hoa-project.net/En/Literature.html#Research
[3] http://keynote.hoa-project.net/Amost12/EDGB12.pdf
[4] https://github.com/hoaproject/Compiler (documentation is under=20
translation)
[5] http://keynote.hoa-project.net/Cstva13/EGB13.pdf
[6] https://github.com/hoaproject/Praspel/tree/master/AssertionChecker
[7] http://atoum.org/
[8] https://github.com/hoaproject/Hoathis-Atoum
[9] https://en.wikipedia.org/wiki/Java_Modeling_Language

--=20
Ivan Enderlin
Developer of Hoa
http://hoa-project.net/

PhD. student at DISC/Femto-ST (Vesontio) and INRIA (Cassis)
http://disc.univ-fcomte.fr/ and http://www.inria.fr/

Member of HTML and WebApps Working Group of W3C
http://w3.org/