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Date: Wed, 11 Feb 2015 12:01:45 +0900
Message-ID: <CAGa2bXZEBhSoZJb9XcbNgHVxzSADk13uLbJDhGudFb2PDrYaAw@mail.gmail.com>
To: Dmitry Stogov <dmitry@zend.com>
Cc: Joe Watkins <pthreads@pthreads.org>, Patrick Schaaf <php@bof.de>, 
	internals <internals@lists.php.net>
Content-Type: multipart/alternative; boundary=001a11c12f8cba4050050ec73b24
Subject: Re: [PHP-DEV] Design by Contract
From: yohgaki@ohgaki.net (Yasuo Ohgaki)

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Content-Type: text/plain; charset=UTF-8

Hi Dmitry and Joe,

On Wed, Feb 11, 2015 at 6:29 AM, Yasuo Ohgaki <yohgaki@ohgaki.net> wrote:

> On Tue, Feb 10, 2015 at 8:53 PM, Dmitry Stogov <dmitry@zend.com> wrote:
>
>> You are welcome to edit https://wiki.php.net/rfc/dbc2
>> It looks like we have similar views, so just make it better in a way you
>> think.
>>
>
> Looks good to me. It's much better than original. Thank you folks.
> We have related issue like how internal module incorporate with DbC.
> However
> these could be future issues.
>

I would like explain one of the reason why I bring up internal module.

http://php.net/manual/en/class.sessionhandlerinterface.php

Session has internal interface definitions like

SessionHandlerInterface {
  /* Methods */
  abstract public bool close ( void )
  abstract public bool destroy ( string $session_id )
  abstract public bool gc ( string $maxlifetime )
  abstract public bool open ( string $save_path , string $name )
  abstract public string read ( string $session_id )
  abstract public bool write ( string $session_id , string $session_data )
}

but it should be like follows to be precise.

SessionHandlerInterface {
  /* Methods */
  abstract public bool close ( void )
    return($ret, is_bool($ret));

  abstract public bool destroy ( string $session_id )
    require(strlen($session_id) > 0)
    return($ret, is_bool($ret));

  abstract public bool gc ( string $maxlifetime )
    require($maxlifetime >= 0)
    return($ret, is_int($ret) && $ret >= -1);

  abstract public bool open ( string $save_path , string $name )
    require(is_string($save_path))
    require(is_string($name));
    return($ret, is_bool($ret));

  abstract public string read ( string $session_id )
    require(strlen($session_id) > 0)
    return($ret, is_bool($ret) || is_string($ret));

  abstract public bool write ( string $session_id , string $session_data )
    require(is_string($session_id) && strlen($session_id) > 0)
    require(is_string($session_data))
    return($ret, is_bool($ret));
}

This definition is more user friendly. There were too many user save
handlers
that do not return proper values because of current interface limitation.

Scalar type and return type hint helps, but it does not cover

    return($ret, is_int($ret) && $ret >= -1);

for example.

If you think this is easy to implement and should be in the RFC, I would
appreciated it
and use it to raise assertion errors just like user class/interface.

BTW, these restrictions are coded as error in current session module and
should
be checked by the module always. It's not mandatory for the RFC, but just a
missing piece.

Regards,

--
Yasuo Ohgaki
yohgaki@ohgaki.net

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