Re: Object constructors/destructors

From	Jerry Stuckle <jstucklex@attglobal.net>
Newsgroups	comp.lang.php
Subject	Re: Object constructors/destructors
Date	2014-02-26 22:30 -0500
Organization	A noiseless patient Spider
Message-ID	<lembfp$3ee$1@dont-email.me> (permalink)
References	(17 earlier) <530e4a38$0$9520$9b4e6d93@newsspool1.arcor-online.net> <lelkn9$919$1@dont-email.me> <530e63d3$0$9502$9b4e6d93@newsspool1.arcor-online.net> <lelp8j$5n8$1@dont-email.me> <530e6d33$0$9521$9b4e6d93@newsspool1.arcor-online.net>

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On 2/26/2014 5:39 PM, Christoph Michael Becker wrote:
> Jerry Stuckle wrote:
>
>> On 2/26/2014 4:59 PM, Christoph Michael Becker wrote:
>>> Jerry Stuckle wrote:
>>>
>>>> On 2/26/2014 3:10 PM, Christoph Michael Becker wrote:
>>>>> Jerry Stuckle wrote:
>>>>>
>>>>>> On 2/25/2014 6:22 PM, Adam Harvey wrote:
>>>>>>> On Tue, 25 Feb 2014 17:01:52 -0500, Jerry Stuckle wrote:
>>>>>>>> On 2/25/2014 4:55 PM, Christoph Michael Becker wrote:
>>>>>>>>> I firmly believe that it wouldn't make sense to call a
>>>>>>>>> (user-defined)
>>>>>>>>> constructor when unserializing or cloning an object.  A constructor
>>>>>>>>> usually serves to initialize an object -- what already had
>>>>>>>>> happened in
>>>>>>>>> both cases.
>>>>>>>>>
>>>>>>>>>
>>>>>>>> It makes perfect sense.  Not everything is necessarily valid in the
>>>>>>>> new
>>>>>>>> object.  For instance, a logging object may require opening the log
>>>>>>>> file.  There are many instances where a resource is no longer
>>>>>>>> available
>>>>>>>> and needs to be recreated.
>>>>>>>
>>>>>>> Indeed, which is why PHP provides the Serializable interface (and,
>>>>>>> for BC
>>>>>>> reasons, also __sleep and __wakeup) to allow those sorts of
>>>>>>> reinitialisation tasks.
>>>>>>>
>>>>>>> I agree with Christoph: since the object is already instantiated, it
>>>>>>> doesn't logically make sense to call the constructor once again.
>>>>>>>
>>>>>>
>>>>>> But the object is NOT instantiated.  It was at one time, then
>>>>>> destroyed.
>>>>>>     When the new script starts, there is no object in existence.
>>>>>>
>>>>>>>>> Jerry Stuckle wrote:
>>>>>>>>>> I know of no other OO language which would allow this.
>>>>>>>>>
>>>>>>>>> Others may.
>>>>>>>>>
>>>>>>>>>
>>>>>>>> None that I know of.  Please name one.
>>>>>>>
>>>>>>> Python's pickle operates the same way:
>>>>>>> http://docs.python.org/2/library/pickle.html#object.__getinitargs__
>>>>>>>
>>>>>>> Providing a way to instantiate objects without calling the
>>>>>>> constructor
>>>>>>> does have valid uses (mostly for testing), which is why PHP 5.4 and
>>>>>>> later
>>>>>>> versions also provide a way to do so via reflection (avoiding the
>>>>>>> unserialize() hack):
>>>>>>> http://php.net/reflectionclass.newinstancewithoutconstructor
>>>>>>>
>>>>>>> Adam
>>>>>>>
>>>>>>
>>>>>> Not knowing Python, I can't say.  But if it is a true object, then
>>>>>> they
>>>>>> are also violating OO principles.
>>>>>>
>>>>>> OO demands creation of a new object requires a constructor call.
>>>>>> Period.
>>>>>
>>>>> Do you understand, what's the purpose of a constructor?  It is there to
>>>>> *initialize* an instance.  If there is nothing to initialize, it is not
>>>>> strictly necessary to call any constructor.
>>>>>
>>>>
>>>> Yes, I understand the purpose of a constructor - it looks like much more
>>>> than you do.
>>>>
>>>>> But anyway, unserializing an object is *not* creating a new object.
>>>>> Consider a class man.  When a new object is instantiated the
>>>>> constructor
>>>>> is called to initialize the person with respective properties (e.g. age
>>>>> = 0).  Later this man goes to sleep (serialize); after he wakes up
>>>>> (unserialize) the constructor is not called again, as this would reset
>>>>> the man to his initial properties, and surely after a good night of
>>>>> sleep one may feel younger, but the age has not been reset.
>>>>>
>>>>
>>>> It is creating a new object.  Before unserialize(), the object does not
>>>> exist - only a bunch of data.   And that data is NOT an object!  You
>>>> cannot call an object method on the data, for instance.  It is no
>>>> different than if the data were stored in a file and loaded in Java or
>>>> C++, for instance.  To create the object requires a call to a
>>>> constructor.
>>>
>>> If you really need to think this way, just take
>>> Serializable::serialize() resp. __sleep() as a destructor and
>>> Serializable::unserialize() resp. __wakeup() as a constructor.
>>> Actually, the documentation of the Serializable interface explaines it
>>> that way.
>>>
>>
>> Then it is wrong in another respect, because the destructor is called
>> after __sleep(), when the object goes out of scope.
>>
>>>>>>             If you think otherwise, I suggest you learn more about
>>>>>> how OO
>>>>>> is supposed to work.  PHP is not a good example.
>>>>>
>>>>> I refrain from commenting this statement.
>>>>>
>>>>
>>>> If you think otherwise, I suggest you learn more about how OO is
>>>> supposed to work.  PHP is not a good example.
>>>
>>> No comment.
>>>
>>
>> No matter how you look at it, PHP's implementation violates OO
>> principles and works differently than any other OO language.
>
> You have claimed that often enough, but yet you have not brought any
> proof.
>
> E.g. what happens in Java if an object that implements the
> java.io.Serializable interface is given as argument to
> java.io.OutputStream.writeObject()?  Is the destructor called?
>

Yes, it is.  But when the new object is created, a constructor is 
called.  You cannot unserialize an object without a constructor being 
called first.

-- 
==================
Remove the "x" from my email address
Jerry Stuckle
jstucklex@attglobal.net
==================

Thread

Operator precedence Christoph Michael Becker <cmbecker69@arcor.de> - 2014-02-23 18:03 +0100
  Re: Operator precedence GS <nomail@nospam.org.invalid> - 2014-02-23 19:42 +0000
    Re: Operator precedence Christoph Michael Becker <cmbecker69@arcor.de> - 2014-02-23 21:23 +0100
    Re: Operator precedence Jerry Stuckle <jstucklex@attglobal.net> - 2014-02-23 16:34 -0500
      Re: Operator precedence Richard Damon <Richard@Damon-Family.org> - 2014-02-23 18:36 -0500
        Re: Operator precedence Jerry Stuckle <jstucklex@attglobal.net> - 2014-02-23 21:09 -0500
          Re: Operator precedence Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-02-24 04:49 +0000
            Re: Operator precedence Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-02-24 12:56 +0100
              Re: Operator precedence Christoph Michael Becker <cmbecker69@arcor.de> - 2014-02-24 17:38 +0100
              Re: Operator precedence Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-02-24 21:25 +0000
                Re: Operator precedence Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-02-25 00:38 +0100
                Re: Operator precedence Christoph Michael Becker <cmbecker69@arcor.de> - 2014-02-25 01:07 +0100
                Re: Operator precedence Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-02-25 01:37 +0100
                Re: Operator precedence Christoph Michael Becker <cmbecker69@arcor.de> - 2014-02-25 02:12 +0100
                Re: Operator precedence Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-02-25 03:29 +0100
                Re: Operator precedence Christoph Michael Becker <cmbecker69@arcor.de> - 2014-02-25 19:41 +0100
                Re: Operator precedence Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-02-25 19:55 +0100
                Re: Operator precedence Christoph Michael Becker <cmbecker69@arcor.de> - 2014-02-25 21:36 +0100
                Re: Operator precedence Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-02-25 03:08 +0000
                Re: Operator precedence Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-02-25 04:17 +0100
                Re: Operator precedence Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-02-25 04:45 +0000
                Re: Operator precedence GS <nomail@nospam.org.invalid> - 2014-02-25 21:45 +0000
            Re: Operator precedence Jerry Stuckle <jstucklex@attglobal.net> - 2014-02-24 07:00 -0500
              Re: Operator precedence Christoph Michael Becker <cmbecker69@arcor.de> - 2014-02-24 18:11 +0100
                Re: Operator precedence Jerry Stuckle <jstucklex@attglobal.net> - 2014-02-24 14:27 -0500
                Re: Operator precedence Christoph Michael Becker <cmbecker69@arcor.de> - 2014-02-25 01:25 +0100
                Re: Operator precedence Jerry Stuckle <jstucklex@attglobal.net> - 2014-02-24 20:40 -0500
              Re: Operator precedence Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-02-24 21:23 +0000
                Re: Operator precedence Jerry Stuckle <jstucklex@attglobal.net> - 2014-02-24 16:45 -0500
                Re: Operator precedence Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-02-25 04:32 +0000
                Re: Operator precedence Jerry Stuckle <jstucklex@attglobal.net> - 2014-02-24 23:47 -0500
                Re: Operator precedence Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-02-25 16:56 +0000
                Re: Operator precedence Jerry Stuckle <jstucklex@attglobal.net> - 2014-02-25 13:59 -0500
                Re: Operator precedence Christoph Michael Becker <cmbecker69@arcor.de> - 2014-02-25 20:19 +0100
                Re: Operator precedence Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-02-25 20:43 +0100
                Re: Operator precedence Jerry Stuckle <jstucklex@attglobal.net> - 2014-02-25 16:02 -0500
                Re: Operator precedence Jerry Stuckle <jstucklex@attglobal.net> - 2014-02-25 16:01 -0500
                Object constructors/destructors (was: Operator precedence) Christoph Michael Becker <cmbecker69@arcor.de> - 2014-02-25 22:19 +0100
                Re: Object constructors/destructors Jerry Stuckle <jstucklex@attglobal.net> - 2014-02-25 16:32 -0500
                Re: Object constructors/destructors Christoph Michael Becker <cmbecker69@arcor.de> - 2014-02-25 22:55 +0100
                Re: Object constructors/destructors Jerry Stuckle <jstucklex@attglobal.net> - 2014-02-25 17:01 -0500
                Re: Object constructors/destructors Adam Harvey <usenet@adamharvey.name> - 2014-02-25 23:22 +0000
                Re: Object constructors/destructors Jerry Stuckle <jstucklex@attglobal.net> - 2014-02-25 21:10 -0500
                Re: Object constructors/destructors Christoph Michael Becker <cmbecker69@arcor.de> - 2014-02-26 21:10 +0100
                Re: Object constructors/destructors Jerry Stuckle <jstucklex@attglobal.net> - 2014-02-26 16:01 -0500
                Re: Object constructors/destructors Christoph Michael Becker <cmbecker69@arcor.de> - 2014-02-26 22:59 +0100
                Re: Object constructors/destructors Jerry Stuckle <jstucklex@attglobal.net> - 2014-02-26 17:19 -0500
                Re: Object constructors/destructors Christoph Michael Becker <cmbecker69@arcor.de> - 2014-02-26 23:39 +0100
                Re: Object constructors/destructors Jerry Stuckle <jstucklex@attglobal.net> - 2014-02-26 22:30 -0500
                Re: Object constructors/destructors Christoph Michael Becker <cmbecker69@arcor.de> - 2014-02-27 18:28 +0100
                Re: Object constructors/destructors Jerry Stuckle <jstucklex@attglobal.net> - 2014-02-27 16:09 -0500
                Re: Object constructors/destructors Christoph Michael Becker <cmbecker69@arcor.de> - 2014-02-28 14:52 +0100
                Re: Object constructors/destructors Jerry Stuckle <jstucklex@attglobal.net> - 2014-02-28 09:08 -0500
                Re: Object constructors/destructors Christoph Michael Becker <cmbecker69@arcor.de> - 2014-02-28 16:52 +0100
                Re: Object constructors/destructors Jerry Stuckle <jstucklex@attglobal.net> - 2014-02-28 11:03 -0500
                Re: Object constructors/destructors Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-02-27 01:00 +0100
                Re: Object constructors/destructors Jerry Stuckle <jstucklex@attglobal.net> - 2014-02-26 22:39 -0500
                Re: Object constructors/destructors Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-02-27 18:29 +0100
                Re: Object constructors/destructors Jerry Stuckle <jstucklex@attglobal.net> - 2014-02-27 16:14 -0500
                Re: Object constructors/destructors Christoph Michael Becker <cmbecker69@arcor.de> - 2014-02-26 00:18 +0100
                Re: Object constructors/destructors Jerry Stuckle <jstucklex@attglobal.net> - 2014-02-25 21:08 -0500
                Re: Object constructors/destructors Richard Damon <Richard@Damon-Family.org> - 2014-02-26 07:50 -0500
                Re: Object constructors/destructors Jerry Stuckle <jstucklex@attglobal.net> - 2014-02-26 08:44 -0500
                Re: Object constructors/destructors Richard Damon <Richard@Damon-Family.org> - 2014-02-26 23:49 -0500
                Re: Object constructors/destructors Jerry Stuckle <jstucklex@attglobal.net> - 2014-02-27 08:25 -0500
                Re: Object constructors/destructors Richard Damon <Richard@Damon-Family.org> - 2014-03-01 12:56 -0500
                Re: Object constructors/destructors Jerry Stuckle <jstucklex@attglobal.net> - 2014-03-01 14:22 -0500
                Re: Object constructors/destructors Richard Damon <Richard@Damon-Family.org> - 2014-03-02 14:28 -0500
                Re: Object constructors/destructors Jerry Stuckle <jstucklex@attglobal.net> - 2014-03-02 15:42 -0500
                Re: Object constructors/destructors Richard Damon <Richard@Damon-Family.org> - 2014-03-02 17:14 -0500
                Re: Object constructors/destructors Jerry Stuckle <jstucklex@attglobal.net> - 2014-03-02 17:48 -0500
                Re: Object constructors/destructors Tim Streater <timstreater@greenbee.net> - 2014-03-02 23:05 +0000
                Re: Operator precedence Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-02-25 21:08 +0000
                Re: Operator precedence Christoph Michael Becker <cmbecker69@arcor.de> - 2014-02-25 22:29 +0100
                Re: Operator precedence Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-02-25 23:15 +0000
              Re: Operator precedence Richard Damon <Richard@Damon-Family.org> - 2014-02-24 22:41 -0500
                Re: Operator precedence Jerry Stuckle <jstucklex@attglobal.net> - 2014-02-24 23:59 -0500
                Re: Operator precedence Richard Damon <Richard@Damon-Family.org> - 2014-03-01 13:39 -0500
                Re: Operator precedence Jerry Stuckle <jstucklex@attglobal.net> - 2014-03-01 14:29 -0500
                Re: Operator precedence Richard Damon <Richard@Damon-Family.org> - 2014-03-02 15:22 -0500
                Re: Operator precedence Jerry Stuckle <jstucklex@attglobal.net> - 2014-03-02 15:49 -0500
                Re: Operator precedence Christoph Michael Becker <cmbecker69@arcor.de> - 2014-02-25 19:15 +0100
  Re: Operator precedence Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-02-23 20:56 +0000
    Re: Operator precedence Christoph Michael Becker <cmbecker69@arcor.de> - 2014-02-24 14:28 +0100

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