--- On Fri, 6/27/08, Thijs Lensselink <dev@xxxxxxxx> wrote:
> From: Thijs Lensselink <dev@xxxxxxxx>
> Subject: Re: unset and circular references
> To: php-general@xxxxxxxxxxxxx
> Date: Friday, June 27, 2008, 5:21 PM
> Quoting Abu Warez <abuwarez@xxxxxxxxx>:
>
> > Hi,
> >
> > I'm using php 5.2.1 on an Ubuntu machine.
> >
> > I have the following class diagram (observer pattern):
> >
> > +---------+ +---------+
> +-------------+
> > | class A |<#>--------->| class B |<
> >--------->| interface C |
> > | | +---------+ |
> |
> > | |-----------------------------------|>|
> |
> > +---------+
> +-------------+
> >
> > in my case class A, the creator of class B, is also
> the class to observe
> > for class B. The following code implements the above
> diagram:
> >
> > <?php
> >
> > interface C
> > {
> > }
> >
> >
> > class B
> > {
> > var $m_ObsC;
> >
> > public function __construct( C $p_ObsC )
> > {
> > $this->m_ObsC = $p_ObsC;
> > }
> >
> > public function __destruct()
> > {
> > echo "B::destruct called
> <br>";
> > }
> > }
> >
> > class A implements C
> > {
> > var $m_b;
> >
> > public function __construct()
> > {
> > $this->m_b = new B( $this );
> > }
> >
> > public function __destruct()
> > {
> > echo "A::destruct called
> <br>";
> > }
> > }
> >
> > $a = new A();
> >
> > unset( $a );
> >
> > echo
> "<br>-----end-of-script----<br>";
> >
> > ?>
> >
> >
> > the output of the above code is:
> >
> > -----end-of-script----
> > A::destruct called
> > B::destruct called
> >
> > So actually the memory used by object $a is freed only
> after the script
> > ends and NOT when unset was called. Now this is a big
> problem for me,
> > because i need to free the memory when I call unset
> and not after the
> > script ends else php runs out of memory in my real
> application. Object $a
> > is not referenced by any other object. I also tried
> with:
> >
> > $this->m_b = new B( &$this );
> >
> > but the result is the same.
> >
> > Any clue how to determine php tho free the memory when
> unset is called and
> > not after the script ends?
> >
> > Thanks,
> >
> > Abu
> >
> >
>
> I think this happens because there is still a reference to
> the B object.
> According to the manual :
>
> The destructor method will be called as soon as all
> references to a
> particular object are removed or when the object is
> explicitly
> destroyed or in any order in shutdown sequence.
>
> So as long as A has a reference to B the __destructor will
> not be called.
>
>
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