Object suicude

[Berislav Lopac]

Is there a way for an object to unset itself in PHP4?

Of course I could unset it from outside, but I would like to keep the code
clean. The object has a method which deletes it's "footprint" in the
database, and as the idea is that we don't need the object once itsin't in
the DB it would be nice if the same method could get rid of the PHP object
iself as well.

Berislav

--
If the Internet is a Marx Brothers movie, and Web, e-mail, and IRC are
Groucho, Chico, and Harpo, then Usenet is Zeppo.

[Andy Hassall]

On Thu, 5 Feb 2004 17:25:28 +0100, "Berislav Lopac" <be************ @dimedia.hr>
wrote:

Is there a way for an object to unset itself in PHP4?

Of course I could unset it from outside, but I would like to keep the code
clean. The object has a method which deletes it's "footprint" in the
database, and as the idea is that we don't need the object once itsin't in
the DB it would be nice if the same method could get rid of the PHP object
iself as well.

The obvious idea of using unset($this) doesn't appear to work:

<?php
class Test
{
var $x = 'x';
function pressBigRedButt on() {
unset($this);
}
}

$test = new Test;
$test->pressBigRedBut ton();

echo $test->x;
?>

(outputs 'x', rather than a warning).

--
Andy Hassall <an**@andyh.co. uk> / Space: disk usage analysis tool
<http://www.andyh.co.uk > / <http://www.andyhsoftwa re.co.uk/space>

[Chung Leong]

unset($this) only remove the variable "this" from the current namespace.
What you want to do is $this = null. That sets what $this was pointing to to
null.

Uzytkownik "Andy Hassall" <an**@andyh.co. uk> napisal w wiadomosci
news:c5******** *************** *********@4ax.c om...

On Thu, 5 Feb 2004 17:25:28 +0100, "Berislav Lopac" <be************ @dimedia.hr> wrote:

Is there a way for an object to unset itself in PHP4?

Of course I could unset it from outside, but I would like to keep the codeclean. The object has a method which deletes it's "footprint" in the
database, and as the idea is that we don't need the object once itsin't inthe DB it would be nice if the same method could get rid of the PHP objectiself as well.

The obvious idea of using unset($this) doesn't appear to work:

<?php
class Test
{
var $x = 'x';
function pressBigRedButt on() {
unset($this);
}
}

$test = new Test;
$test->pressBigRedBut ton();

echo $test->x;
?>

(outputs 'x', rather than a warning).

--
Andy Hassall <an**@andyh.co. uk> / Space: disk usage analysis tool
<http://www.andyh.co.uk > / <http://www.andyhsoftwa re.co.uk/space>

[Phil Powell]

Have a question about $this = null:

In PHP is this its equivalent of destroying an object, say, if you
will, Garbage Collection? I am working on a project that has anywhere
between 10 - 50 different instances occurring at one time (I kid you
not!) and realize this will turn into a horrific bottleneck unless
there is some means of garbage collection.

Thanx
Phil

"Chung Leong" <ch***********@ hotmail.com> wrote in message news:<vM******* *************@c omcast.com>...

unset($this) only remove the variable "this" from the current namespace.
What you want to do is $this = null. That sets what $this was pointing to to
null.

Uzytkownik "Andy Hassall" <an**@andyh.co. uk> napisal w wiadomosci
news:c5******** *************** *********@4ax.c om...

On Thu, 5 Feb 2004 17:25:28 +0100, "Berislav Lopac"

<be************ @dimedia.hr>

wrote:

Is there a way for an object to unset itself in PHP4?

Of course I could unset it from outside, but I would like to keep the codeclean. The object has a method which deletes it's "footprint" in the
database, and as the idea is that we don't need the object once itsin't inthe DB it would be nice if the same method could get rid of the PHP objectiself as well.

The obvious idea of using unset($this) doesn't appear to work:

<?php
class Test
{
var $x = 'x';
function pressBigRedButt on() {
unset($this);
}
}

$test = new Test;
$test->pressBigRedBut ton();

echo $test->x;
?>

(outputs 'x', rather than a warning).

--
Andy Hassall <an**@andyh.co. uk> / Space: disk usage analysis tool
<http://www.andyh.co.uk > / <http://www.andyhsoftwa re.co.uk/space>

[Andy Hassall]

On Thu, 5 Feb 2004 18:16:47 -0500, "Chung Leong" <ch***********@ hotmail.com>
wrote:

unset($this) only remove the variable "this" from the current namespace.
What you want to do is $this = null. That sets what $this was pointing to to
null.

Ah - thanks, I wasn't aware of the distinction. Looks like this is what Phil
is looking for, as a quick test appears to show it does destroy the object.

--
Andy Hassall <an**@andyh.co. uk> / Space: disk usage analysis tool
<http://www.andyh.co.uk > / <http://www.andyhsoftwa re.co.uk/space>

[Chung Leong]

In theory, yes. In practice, I have not a clue. On my server the Apache
process regularly chew up half a gig of memory.

Uzytkownik "Phil Powell" <so*****@erols. com> napisal w wiadomosci
news:1c******** *************** ***@posting.goo gle.com...

Have a question about $this = null:

In PHP is this its equivalent of destroying an object, say, if you
will, Garbage Collection? I am working on a project that has anywhere
between 10 - 50 different instances occurring at one time (I kid you
not!) and realize this will turn into a horrific bottleneck unless
there is some means of garbage collection.

Thanx
Phil

"Chung Leong" <ch***********@ hotmail.com> wrote in message

news:<vM******* *************@c omcast.com>...

unset($this) only remove the variable "this" from the current namespace.
What you want to do is $this = null. That sets what $this was pointing to to null.

Uzytkownik "Andy Hassall" <an**@andyh.co. uk> napisal w wiadomosci
news:c5******** *************** *********@4ax.c om...

On Thu, 5 Feb 2004 17:25:28 +0100, "Berislav Lopac"

<be************ @dimedia.hr>

wrote:

>Is there a way for an object to unset itself in PHP4?
>
>Of course I could unset it from outside, but I would like to keep the

code

>clean. The object has a method which deletes it's "footprint" in the
>database, and as the idea is that we don't need the object once

itsin't in

>the DB it would be nice if the same method could get rid of the PHP

object

>iself as well.

The obvious idea of using unset($this) doesn't appear to work:

<?php
class Test
{
var $x = 'x';
function pressBigRedButt on() {
unset($this);
}
}

$test = new Test;
$test->pressBigRedBut ton();

echo $test->x;
?>

(outputs 'x', rather than a warning).

--
Andy Hassall <an**@andyh.co. uk> / Space: disk usage analysis tool
<http://www.andyh.co.uk > / <http://www.andyhsoftwa re.co.uk/space>

[Alex Farran]

Andy Hassall writes:

On Thu, 5 Feb 2004 18:16:47 -0500, "Chung Leong" <ch***********@ hotmail.com>
wrote:

unset($this) only remove the variable "this" from the current namespace.
What you want to do is $this = null. That sets what $this was pointing to to
null.

Ah - thanks, I wasn't aware of the distinction. Looks like this is what Phil
is looking for, as a quick test appears to show it does destroy the object.

Well that is interesting. I had to try it myself. Conceptually $this
is just another parameter passed by reference, and you can do anything
you want to it, including assigning it a completely different object.

I adapted the suicide test to do this -

<?php
class Transmute {
var $y = 'y';
}

class Test {
var $x = 'x';
function pressBigRedButt on() {
$this= new Transmute();
}
}
$test = new Test;
echo $test->x;
$test->pressBigRedBut ton();
echo $test->x;
echo $test->y;
?>

Returns

x
Notice: Undefined property: x in suicide.php on line 16
y

--

__o Alex Farran
_`\<,_ Analyst / Programmer
(_)/ (_) www.alexfarran.com

[Zurab Davitiani]

Phil Powell wrote:

Have a question about $this = null:

In PHP is this its equivalent of destroying an object, say, if you
will, Garbage Collection? I am working on a project that has anywhere
between 10 - 50 different instances occurring at one time (I kid you
not!) and realize this will turn into a horrific bottleneck unless
there is some means of garbage collection.

There's none in PHP4. Even if you do $someObject = null or unset() or
anything else it will not free up memory used by that object. Memory is
only freed up when the script execution ends.

This only applies to objects and not other types like arrays, strings, etc.

[Alex Farran]

Zurab Davitiani writes:

Phil Powell wrote:

Have a question about $this = null:

In PHP is this its equivalent of destroying an object, say, if you
will, Garbage Collection? I am working on a project that has anywhere
between 10 - 50 different instances occurring at one time (I kid you
not!) and realize this will turn into a horrific bottleneck unless
there is some means of garbage collection.

There's none in PHP4. Even if you do $someObject = null or unset() or
anything else it will not free up memory used by that object. Memory is
only freed up when the script execution ends.

What makes you think that? PHP4's garbage collection algorithm is an
unsophisticated reference counter, so it may not be the most efficient
in the world, but I'd be very surprised if objects weren't GC'd.
--

__o Alex Farran
_`\<,_ Analyst / Programmer
(_)/ (_) www.alexfarran.com

[Zurab Davitiani]

Alex Farran wrote:

There's none in PHP4. Even if you do $someObject = null or unset() or
anything else it will not free up memory used by that object. Memory is
only freed up when the script execution ends.

What makes you think that? PHP4's garbage collection algorithm is an
unsophisticated reference counter, so it may not be the most efficient
in the world, but I'd be very surprised if objects weren't GC'd.

I can't see how they are. I've tried few scripts quite a few times and
different ways that create new objects in a for-loop. Memory consumption
never goes down, but only increases as the script continues to run.
Eventually, the available memory is used up and you either get a fatal
error (unable to allocate memory), or the process simply crashes, depending
on your version of PHP4.

This only happens with objects, but not with other types, as I said; even if
you try to unset or =null or reassign the same variable name to another
object - doesn't matter how you do it.

I'd be interested to see what method you are suggesting to use that will
properly destroy the object, freeing the associated memory. It just doesn't
happen automatically with the garbage collection like with the other types
of variables.