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Object Destruction (or how to destroy instance)

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Oleg Richards

Object Destruction (or how to destroy instance)

Hello Guys!

Maybe this question is more about smalltalk than about seaside, so
i'm sorry.

In my reporting application i have following problem:
Some components of my seaside application working with Business Model
copies.
I do it to have ability to revert changes. If user wants to save
changes, database collection
just replaces old business objects with their updated copies. So
everything works just fine.

But there is a question: If i ask VisualWorks to show all instances
of Business Model, i can also
see old models, which were replaced by newer ones in DB collections.
So some instances "just flying
in the air". How can i destroy them (something like calling
destructor in C++). Or thats a not a problem and
they will be killed by garbage collector sometime? If so, when they
will be killed?

Cheers, Oleg
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Boris Popov, DeepCove Labs (SNN)

Re: Object Destruction (or how to destroy instance)

Re: [Seaside] Object Destruction (or how to destroy instance)

Inspect those instances and lookup refrences to them via the menu bar. They will be collected only if no one has a hard reference to them.

Cheers!

-Boris
(Sent from a BlackBerry)

----- Original Message -----
From: [hidden email] <[hidden email]>
To: [hidden email] <[hidden email]>
Sent: Wed Sep 12 01:43:01 2007
Subject: [Seaside] Object Destruction (or how to destroy instance)

Hello Guys!

Maybe this question is more about smalltalk than about seaside, so
i'm sorry.

In my reporting application i have following problem:
Some components of my seaside application working with Business Model
copies.
I do it to have ability to revert changes. If user wants to save
changes, database collection
just replaces old business objects with their updated copies. So
everything works just fine.

But there is a question: If i ask VisualWorks to show all instances
of Business Model, i can also
see old models, which were replaced by newer ones in DB collections.
So some instances "just flying
in the air". How can i destroy them (something like calling
destructor in C++). Or thats a not a problem and
they will be killed by garbage collector sometime? If so, when they
will be killed?

Cheers, Oleg
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Sebastian Sastre-2

RE: Object Destruction (or how to destroy instance)

In reply to this post by Oleg Richards

> -----Mensaje original-----
> De: [hidden email]
> [mailto:[hidden email]] En nombre
> de Oleg Richards
> Enviado el: Miércoles, 12 de Septiembre de 2007 05:43
> Para: [hidden email]
> Asunto: [Seaside] Object Destruction (or how to destroy instance)
>
> Hello Guys!
>
> Maybe this question is more about smalltalk than about
> seaside, so i'm sorry.
>
> In my reporting application i have following problem:
> Some components of my seaside application working with
> Business Model copies.
> I do it to have ability to revert changes. If user wants to
> save changes, database collection just replaces old business
> objects with their updated copies. So everything works just fine.
>
> But there is a question: If i ask VisualWorks to show all
> instances of Business Model, i can also see old models, which
> were replaced by newer ones in DB collections.
> So some instances "just flying
> in the air". How can i destroy them (something like calling
> destructor in C++). Or thats a not a problem and they will be
> killed by garbage collector sometime? If so, when they will be killed?
>
> Cheers, Oleg

Probably the instances are not that *in the air* as you may think. This
could happen if at least one object has direct references to them (or a root
of the graph of them). Make a double check to see if you really make them
nobody knows them anymore. The rest of the work is garbage collectors magic,

Cheers,

Sebastian

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Oleg Richards

Re: Object Destruction (or how to destroy instance)

In reply to this post by Oleg Richards

Hello!

I've tried some of your recommendations, but after analyzing
owners of BusinessObject's in WeakArray (from query all class
instances).

I see some references: They are referenced by some Seaside components.
But for now only one component is active. System doesn't have another
components.
They are only called from root task or from some callbacks of anchors
with: call: (SOReportTable new: aReport).

Code looks like that:

|myAnswer|
myAnswer := self call: (SOReportTable new: report copy).
myAnswer ifNotNil: [ report := myAnswer ]
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Sebastian Sastre-2

RE: Re: Object Destruction (or how to destroy instance)

Well garbage collection does not make differences between objects. Or they
are in use (referenced by other no matter who) or they not. There resides
it's discern.

I don't know what do you mean by "active" components or non active ones, but
if any object know another no matter what, the system guarantees you that it
will not be reclaimed by GC.

cheers,

Sebastian Sastre

> -----Mensaje original-----
> De: [hidden email]
> [mailto:[hidden email]] En nombre
> de Oleg Richards
> Enviado el: Miércoles, 12 de Septiembre de 2007 14:05
> Para: [hidden email]
> Asunto: [Seaside] Re: Object Destruction (or how to destroy instance)
>
> Hello!
>
> I've tried some of your recommendations, but after analyzing
> owners of BusinessObject's in WeakArray (from query all class
> instances).
>
> I see some references: They are referenced by some Seaside components.
> But for now only one component is active. System doesn't have
> another components.
> They are only called from root task or from some callbacks of anchors
> with: call: (SOReportTable new: aReport).
>
> Code looks like that:
>
>
> |myAnswer|
> myAnswer := self call: (SOReportTable new: report copy).
> myAnswer ifNotNil: [ report := myAnswer ]
> _______________________________________________
> Seaside mailing list
> [hidden email]
> http://lists.squeakfoundation.org/cgi-bin/mailman/listinfo/seaside

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Oleg Richards

Re: Object Destruction (or how to destroy instance)

In reply to this post by Oleg Richards

I understand. Active components - components that i have on my screen..

Others was used in call.. And now they returned answer and i think
that they are not active.
But they still have link to report, which they returned via answer.
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Lukas Renggli

Re: Re: Object Destruction (or how to destroy instance)

> Others was used in call.. And now they returned answer and i think
> that they are not active.
> But they still have link to report, which they returned via answer.

Inactive components don't immediately disappear from the
object-memory. The user of your application might hit the back button
anytime and then the state of the component tree needs to be restored.
Components that are not visible anymore will eventually be garbage
collected, either after a couple of requests (~10) or at session
timeout.

Cheers,
Lukas

--
Lukas Renggli
http://www.lukas-renggli.ch
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Oleg Richards

Re: Object Destruction (or how to destroy instance)

In reply to this post by Oleg Richards

I think, that they are still alive, because of WAStateHolder.
If system remembers each state it also should remember all variables
for this step.

But when it will be cleared?
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