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Re: out of sheer curiosity... [message #177558 is a reply to message #177554]

Mon, 09 April 2012 20:50

Thomas Mlynarczyk
Messages: 131
Registered: September 2010

Karma:

Senior Member

Jerry Stuckle schrieb:

> In object oriented programming, a new object can ONLY be created by
> calling a constructor. As noted above, different languages have
> different terms for them. But a constructor MUST be called according to
> OO principles.

Just to avoid confusion: When a new object is created, PHP must do some
work under the hood like allocating memory etc. and this of course is
"construction" work which is always done and in that sense a constructor
is indeed always called.

But after that, there is (or is not) the call to __construct(). And now
that I think of it, the name __construct() is actually not quite
correct, since the actual construction of the object is already done at
that point. What __construct() really does is perform some
initialization (in Python, the corresponding method is indeed called
__init__()).

And this initialization is not needed (or might even prove harmful) when
the object is copied rather than created from scratch, because in that
case the initialization was already done on the original object and the
copy was thus created from an already initialized object and it will
"inherit" the initialized state. Instead, there are __clone() and
__wakeup() which replace __construct() and can do different
initialization tasks depending on how the object was created.

Therefore I must correct my earlier remark about neither __clone() nor
__wakeup() being constructors: __construct(), __clone() and __wakeup()
are all "of the same kind" -- performing initialization of an object
depending on how it was created.

On the other hand, __sleep() is not a destructor, because nothing is
destroyed when it is called. Note that __sleep() is supposed to return
an array, contrary to __destruct(). So, while the names __sleep() and
__wakeup() suggest a correspondence like __destruct() and __construct(),
this is not the case, since __sleep() is called on the original object,
while __wakeup() is called on the resurrected copy, so they're not
called on the same object.

Anyway, I must thank you for making me think more thoroughly about this.

Greetings,
Thomas

--
Ce n'est pas parce qu'ils sont nombreux à avoir tort qu'ils ont raison!
(Coluche)

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[Message index]

		out of sheer curiosity... By: Leonardo Azpurua on Tue, 27 March 2012 17:01
		Re: out of sheer curiosity... By: alvaro.NOSPAMTHANX on Tue, 27 March 2012 17:06
		Re: out of sheer curiosity... By: Leonardo Azpurua on Tue, 27 March 2012 17:34
		Re: out of sheer curiosity... By: Thomas 'PointedEars' on Wed, 28 March 2012 19:12
		Re: out of sheer curiosity... By: Leonardo Azpurua on Thu, 29 March 2012 00:53
		Re: out of sheer curiosity... By: M. Strobel on Thu, 29 March 2012 08:00
		Re: out of sheer curiosity... By: Leonardo Azpurua on Thu, 29 March 2012 09:53
		Re: out of sheer curiosity... By: The Natural Philosoph on Thu, 29 March 2012 10:46
		Re: out of sheer curiosity... By: M. Strobel on Thu, 29 March 2012 12:02
		Re: out of sheer curiosity... By: Erwin Moller on Thu, 29 March 2012 12:33
		Re: out of sheer curiosity... By: The Natural Philosoph on Thu, 29 March 2012 13:37
		Re: out of sheer curiosity... By: Erwin Moller on Thu, 29 March 2012 13:59
		Re: out of sheer curiosity... By: The Natural Philosoph on Thu, 29 March 2012 16:58
		Re: out of sheer curiosity... By: Jerry Stuckle on Thu, 29 March 2012 13:39
		Re: out of sheer curiosity... By: Erwin Moller on Thu, 29 March 2012 14:21
		Re: out of sheer curiosity... By: The Natural Philosoph on Thu, 29 March 2012 17:09
		Re: out of sheer curiosity... By: Tim Streater on Thu, 29 March 2012 21:07
		Re: out of sheer curiosity... By: M. Strobel on Thu, 29 March 2012 21:43
		Re: out of sheer curiosity... By: The Natural Philosoph on Fri, 30 March 2012 03:52
		Re: out of sheer curiosity... By: Jerry Stuckle on Thu, 29 March 2012 20:11
		Re: out of sheer curiosity... By: Tim Streater on Thu, 29 March 2012 21:01
		Re: out of sheer curiosity... By: Jerry Stuckle on Thu, 29 March 2012 23:29
		Re: out of sheer curiosity... By: M. Strobel on Sun, 08 April 2012 20:50
		Re: out of sheer curiosity... By: Jerry Stuckle on Sun, 08 April 2012 21:15
		Re: out of sheer curiosity... By: M. Strobel on Sun, 08 April 2012 22:39
		Re: out of sheer curiosity... By: The Natural Philosoph on Sun, 08 April 2012 23:59
		Re: out of sheer curiosity... By: Jerry Stuckle on Mon, 09 April 2012 00:28
		Re: out of sheer curiosity... By: Jerry Stuckle on Mon, 09 April 2012 00:24
		Re: out of sheer curiosity... By: M. Strobel on Mon, 09 April 2012 09:29
		Re: out of sheer curiosity... By: Jerry Stuckle on Mon, 09 April 2012 12:27
		Re: out of sheer curiosity... By: Thomas Mlynarczyk on Mon, 09 April 2012 13:20
		Re: out of sheer curiosity... By: Jerry Stuckle on Mon, 09 April 2012 16:03
		Re: out of sheer curiosity... By: Thomas Mlynarczyk on Mon, 09 April 2012 18:04
		Re: out of sheer curiosity... By: Jerry Stuckle on Mon, 09 April 2012 18:37
		Re: out of sheer curiosity... By: Thomas Mlynarczyk on Mon, 09 April 2012 20:50
		Re: out of sheer curiosity... By: Jerry Stuckle on Tue, 10 April 2012 00:17
		Re: out of sheer curiosity... By: M. Strobel on Tue, 10 April 2012 08:05
		Re: out of sheer curiosity... By: Thomas Mlynarczyk on Tue, 10 April 2012 11:28
		Re: out of sheer curiosity... By: M. Strobel on Tue, 10 April 2012 16:54
		Re: out of sheer curiosity... By: Thomas Mlynarczyk on Tue, 10 April 2012 18:10
		Re: out of sheer curiosity... By: M. Strobel on Tue, 10 April 2012 18:23
		Re: out of sheer curiosity... By: Thomas Mlynarczyk on Tue, 10 April 2012 21:17
		Re: out of sheer curiosity... By: Jerry Stuckle on Tue, 10 April 2012 21:11
		Re: out of sheer curiosity... By: Thomas Mlynarczyk on Tue, 10 April 2012 21:30
		Re: out of sheer curiosity... By: Jerry Stuckle on Tue, 10 April 2012 23:43
		Re: out of sheer curiosity... By: Jerry Stuckle on Tue, 10 April 2012 21:08
		Re: out of sheer curiosity... By: M. Strobel on Wed, 11 April 2012 08:40
		Re: out of sheer curiosity... By: Jerry Stuckle on Tue, 10 April 2012 11:58
		Re: out of sheer curiosity... By: Tim Streater on Tue, 10 April 2012 15:04
		Re: out of sheer curiosity... By: Jerry Stuckle on Tue, 10 April 2012 16:10
		Re: out of sheer curiosity... By: Thomas Mlynarczyk on Tue, 10 April 2012 16:18
		Re: out of sheer curiosity... By: The Natural Philosoph on Tue, 10 April 2012 17:20
		Re: out of sheer curiosity... By: M. Strobel on Tue, 10 April 2012 17:31
		Re: out of sheer curiosity... By: Jerry Stuckle on Tue, 10 April 2012 21:20
		Re: out of sheer curiosity... By: Thomas Mlynarczyk on Tue, 10 April 2012 21:57
		Re: out of sheer curiosity... By: Jerry Stuckle on Tue, 10 April 2012 23:50
		Re: out of sheer curiosity... By: Tim Streater on Tue, 10 April 2012 16:41
		Re: out of sheer curiosity... By: Thomas Mlynarczyk on Tue, 10 April 2012 15:25
		Re: out of sheer curiosity... By: Jerry Stuckle on Tue, 10 April 2012 16:16
		Re: out of sheer curiosity... By: Thomas Mlynarczyk on Tue, 10 April 2012 11:44
		Re: out of sheer curiosity... By: Jerry Stuckle on Tue, 10 April 2012 12:04
		Re: out of sheer curiosity... By: Thomas Mlynarczyk on Tue, 10 April 2012 15:37
		Re: out of sheer curiosity... By: Jerry Stuckle on Tue, 10 April 2012 16:19
		Re: out of sheer curiosity... By: Thomas Mlynarczyk on Tue, 10 April 2012 16:44
		Re: out of sheer curiosity... By: Jerry Stuckle on Tue, 10 April 2012 21:23
		Re: out of sheer curiosity... By: Scott Johnson on Mon, 09 April 2012 18:50
		Re: out of sheer curiosity... By: Thomas Mlynarczyk on Mon, 09 April 2012 21:03
		Re: out of sheer curiosity... By: Scott Johnson on Mon, 09 April 2012 22:27
		Re: out of sheer curiosity... By: Jerry Stuckle on Tue, 10 April 2012 00:25
		Re: out of sheer curiosity... By: Thomas Mlynarczyk on Tue, 10 April 2012 10:48
		Re: out of sheer curiosity... By: Jerry Stuckle on Tue, 10 April 2012 12:06
		Re: out of sheer curiosity... By: Leonardo Azpurua on Tue, 10 April 2012 12:22
		Re: out of sheer curiosity... By: Jerry Stuckle on Tue, 10 April 2012 16:20
		Re: out of sheer curiosity... By: Leonardo Azpurua on Tue, 10 April 2012 16:33
		Re: out of sheer curiosity... By: Jerry Stuckle on Tue, 10 April 2012 21:28
		Re: out of sheer curiosity... By: Thomas Mlynarczyk on Tue, 10 April 2012 22:13
		Re: out of sheer curiosity... By: Jerry Stuckle on Tue, 10 April 2012 23:53
		Re: out of sheer curiosity... By: Thomas Mlynarczyk on Wed, 11 April 2012 20:17
		Re: out of sheer curiosity... By: Jerry Stuckle on Wed, 11 April 2012 20:30
		Re: out of sheer curiosity... By: Jerry Stuckle on Tue, 10 April 2012 00:22
		Re: out of sheer curiosity... By: Thomas Mlynarczyk on Tue, 10 April 2012 10:43
		Re: out of sheer curiosity... By: Jerry Stuckle on Tue, 10 April 2012 12:11
		Re: out of sheer curiosity... By: Thomas Mlynarczyk on Tue, 10 April 2012 16:15
		Re: out of sheer curiosity... By: M. Strobel on Tue, 10 April 2012 17:09
		Re: out of sheer curiosity... By: Thomas Mlynarczyk on Tue, 10 April 2012 18:17
		Re: out of sheer curiosity... By: M. Strobel on Tue, 10 April 2012 18:25
		Re: out of sheer curiosity... By: Thomas Mlynarczyk on Tue, 10 April 2012 21:21
		Re: out of sheer curiosity... By: Jerry Stuckle on Tue, 10 April 2012 21:34
		Re: out of sheer curiosity... By: Thomas Mlynarczyk on Tue, 10 April 2012 23:00
		Re: out of sheer curiosity... By: Jerry Stuckle on Tue, 10 April 2012 23:54
		Re: out of sheer curiosity... By: Thomas Mlynarczyk on Wed, 11 April 2012 20:10
		Re: out of sheer curiosity... By: Jerry Stuckle on Wed, 11 April 2012 20:31
		Re: out of sheer curiosity... By: Thomas Mlynarczyk on Wed, 11 April 2012 20:40
		Re: out of sheer curiosity... By: Jerry Stuckle on Thu, 12 April 2012 04:02
		Re: out of sheer curiosity... By: M. Strobel on Thu, 12 April 2012 10:00
		Re: out of sheer curiosity... By: Jerry Stuckle on Thu, 12 April 2012 11:45

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