| Re: object reference destroy [message #67049] |
Wed, 24 June 2009 11:42 |
David Fanning
Messages: 11724
Registered: August 2001
|
Senior Member |
|
|
BlackMage writes:
> An alternative is to implement reference counting
Humm. Thought I mentioned this. ;-)
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Sepore ma de ni thui. ("Perhaps thou speakest truth.")
|
|
|
|
| Re: object reference destroy [message #67051 is a reply to message #67049] |
Wed, 24 June 2009 11:33  |
BlackMage
Messages: 2
Registered: August 2008
|
Junior Member |
|
|
An alternative is to implement reference counting. I have implemented
this for my own code and found it very effective, all my classes have
the reference counting class as the root of their inheritance. When
the reference-counting object is created or another object tells it
that it 'owns' a reference to it, the count increases. Once other
objects no longer need the owning reference, they tell the reference-
counting object and the count decreases. Once the count hits zero, the
reference-counting object destroys itself. If the reference-counting
object is destroyed with a non-zero count, it complains and this
assists debugging.
This approach has been very effective for me in object management as I
am no longer trying to work out exactly what part of my code holds the
final reference to any given object so I can destroy it when, and only
when, it is no longer needed. It's especially useful if you have
multiple collections of the same object references e.g. search trees
or linked lists.
|
|
|
|
| Re: object reference destroy [message #67103 is a reply to message #67051] |
Mon, 22 June 2009 09:30 |
Doug Edmundson
Messages: 58
Registered: November 2005
|
Member |
|
|
Hi crane,
The get() method returns a reference to the stored object - not some
kind of copy of the original. So when you delete the gotten object, the
original is destroyed.
You can eat as much of your cake as you want, just don't throw it away
until you really don't want the cake any more. ;-)
Hope this helps,
Doug
crane wrote:
> hi, people
>
> I have a container to hold a object, and I need to use this object
> often. In order to avoid memory leakage, i have to destroy the object
> reference after use. But once i destroy the object reference, the
> object in the container is also destroy, because they are pointing to
> the same object. For example:
>
> ; put a object into the container
> container = obj_new('idl_container')
> obj = obj_new('myclass')
> container->add, obj
>
> ; get the object for the first time
> objref _1= container->get(/all)
> ....
> ; destroy the object reference for the first time. (memory reason)
> obj_destroy, objref_1
>
> ; need to get the object from the container second time
> objref_2= container->get(/all)
> ; but objref_2 is not a valid object anymore, because i destroy the
> object in the previous section.
> IDL> print, obj_valid(objref_2)
> 0
>
>
> I like to use container to hold object, it is convenience to play with
> objects. can somebody help me through this problem or have another
> idea for alternative. thanks.
>
>
>
>
>
>
>
>
>
|
|
|
|
| Re: object reference destroy [message #67105 is a reply to message #67103] |
Mon, 22 June 2009 05:40 |
greg.addr
Messages: 160
Registered: May 2007
|
Senior Member |
|
|
;put a cake into the container
container = obj_new('IDLtin')
cake = obj_new('IDLcake')
container->add, cake
;get the cake out for the first time
objref_1= container->get(/all)
....
;eat the cake for the first time. (hunger reason)
obj_eat, objref_1
;need to get the cake out from the container second time
objref_2= container->get(/all)
;but objref_2 is not a cake, because i ate it in the previous
section.
IDL> print, obj_valid(objref_2)
0
On Jun 22, 11:53 am, crane <dos...@163.com> wrote:
> hi, people
>
> I have a container to hold a object, and I need to use this object
> often. In order to avoid memory leakage, i have to destroy the object
> reference after use. But once i destroy the object reference, the
> object in the container is also destroy, because they are pointing to
> the same object. For example:
>
> ; put a object into the container
> container = obj_new('idl_container')
> obj = obj_new('myclass')
> container->add, obj
>
> ; get the object for the first time
> objref _1= container->get(/all)
> ....
> ; destroy the object reference for the first time. (memory reason)
> obj_destroy, objref_1
>
> ; need to get the object from the container second time
> objref_2= container->get(/all)
> ; but objref_2 is not a valid object anymore, because i destroy the
> object in the previous section.
> IDL> print, obj_valid(objref_2)
> 0
>
> I like to use container to hold object, it is convenience to play with
> objects. can somebody help me through this problem or have another
> idea for alternative. thanks.
|
|
|
|
| Re: object reference destroy [message #67107 is a reply to message #67105] |
Mon, 22 June 2009 05:27 |
David Fanning
Messages: 11724
Registered: August 2001
|
Senior Member |
|
|
crane writes:
> I have a container to hold a object, and I need to use this object
> often. In order to avoid memory leakage, i have to destroy the object
> reference after use. But once i destroy the object reference, the
> object in the container is also destroy, because they are pointing to
> the same object. For example:
> ...
> I like to use container to hold object, it is convenience to play with
> objects. can somebody help me through this problem or have another
> idea for alternative.
You might want to have a look at the CatContainer object
in my Catalyst Library code. It reference counts objects
that are added to it by adding a "parent" to the added
object's "people interested in me" list. When the container
is destroyed it takes its name off the "people interested
in me" list and the added object is only destroyed if the
container sees there is no more interest in the object.
That is, the object is destroyed if the container was the
last "person" interested in the object.
Provisions are made in the object to *never* destroy the
object's added to it, if that is what you would prefer, too.
http://www.dfanning.com/programs/catalyst/source/core/catcon tainer__defi
ne.pro
Your objects would simply inherit CatContainer to have this
functionality.
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Sepore ma de ni thui. ("Perhaps thou speakest truth.")
|
|
|
|
comp.lang.idl-pvwave archive
Members
Search
Help
Login
Home
