Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:71721
Mailing-List: contact internals-help@lists.php.net; run by ezmlm
Received-SPF: pass (pb1.pair.com: domain gmail.com designates 209.85.216.52 as permitted sender)
MIME-Version: 1.0
In-Reply-To: <CAGa2bXaQBM4_8FN56Cxt8Ubz4u-MzdQhp7EuAvxdgO-mYTXJTA@mail.gmail.com>
References: <CAGa2bXa+VdBP+eDmGLYSX+94+fHfmAqASA_3aZOj_JrAVg1fgw@mail.gmail.com>
 <CALtuQzAXGFz3MZKbZWMAxLEkvSuNXtnd7wtKQmAaARxCE6p2-w@mail.gmail.com> <CAGa2bXaQBM4_8FN56Cxt8Ubz4u-MzdQhp7EuAvxdgO-mYTXJTA@mail.gmail.com>
Date: Wed, 29 Jan 2014 12:09:39 +0100
Message-ID: <CALtuQzCLNbPxV405J1yJPfzeFsz+HgrN9dKrA-3aykkzQhRW2A@mail.gmail.com>
To: Yasuo Ohgaki <yohgaki@ohgaki.net>
Cc: "internals@lists.php.net" <internals@lists.php.net>
Content-Type: multipart/alternative; boundary=001a11c13c5e804d3304f119fc32
Subject: Re: [PHP-DEV] DbC for PHP?
From: krebs.seb@gmail.com (Sebastian Krebs)

--001a11c13c5e804d3304f119fc32
Content-Type: text/plain; charset=ISO-8859-1

2014-01-29 Yasuo Ohgaki <yohgaki@ohgaki.net>

> Hi Sebastian,
>
> On Tue, Jan 28, 2014 at 5:36 PM, Sebastian Krebs <krebs.seb@gmail.com>wrote:
>
>> 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/5b0a53b9732f0e4dbe79345212c84c74526def3b
>>> :
>>>
>>> It could be done with dbc mode INI switch as follows.
>>>
>>> When dbc=on, 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.
>>>
>>
>> Couldn't you achieve the same with assert()?
>>
>
> Assert can be used for DbC and there are such implementations.
>
> Precondition is easy with assert(), but post condition is rather difficult
> since
> we need assert() before every 'return'.
>

Well .. Yeah. But that is difficult?


> This could damage production code
> (code executed on production environment) and contract readability. It
> increases
> chances of omitting post condition check by mistake.
>

This is possible with every implementation...


>
> Similar mistake may happen with this.
> We may better to have option to warn non existent pre/post check.
>
>
> Like Alexander explained, pure OO code can use DbC. It may be enough
> for people who are interested in DbC.
>
> This is just an idea. It's simple, powerful and easy to adopt. Since there
> is no DbC code in production code, it's fast while assert() need
> compilation
> overhead. It does not matter much with opcache, though.
>

No, at least not measurable. You can disable it. In that case it behaves
like an empty function body.


>
> With this approach, user has to look up contract in other file. This is
> disadvantage over other methods.
>
> I wander how many of us are interested in such feature.
>
> Regards,
>
> --
> Yasuo Ohgaki
> yohgaki@ohgaki.net
>
>


-- 
github.com/KingCrunch

--001a11c13c5e804d3304f119fc32--