Aw: [Newbies] remove allInstances?

[Rudolf Rednose]

Caution: lowskilled hobbyist
 
anyway:
 
Hi Joseph,
Smalltalk garbageCollect does that automatically for you
BUT
it removes only objects that are not in connection with other objects.
 
So you have to cut loose all connections from other objects to your Book 
instances.
 
Maybe you have variables within a workspace pointing to some Book instances.
Or a list object with references to all of your books. (How do you get to your 
books?)
 
Even an inspector, explorer or debugger pointing to a Book instance keeps the 
garbagecollector from removing them.
 
Hope that helps a little

Rudolf
 
-- 
 
 

Gesendet: Freitag, 23. September 2016 um 07:40 Uhr
Von: "Joseph Alotta" 
An: beginners@lists.squeakfoundation.org
Betreff: [Newbies] remove allInstances?
Greetings,

The main program I am working on now is called Books.

If I evaluate

Books allInstances => anOrderedCollection( aBook aBook aBook )

How do I set them all equal to nil like

Books removeAllInstances.

Books allInstances => anOrderedCollection().


Sincerely,

Joseph.


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Re: [Newbies] remove allInstances?

[David Corking]

Joseph: I agree with Rudolf. See also
http://forum.world.st/Deleting-an-instance-td3328590.html

Have fun! David
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[Newbies] remove allInstances?

[Louis LaBrunda]

Hi Joseph,

Try:

Books allInstances do: [:b | b become: nil].

Lou

On Fri, 23 Sep 2016 00:40:33 -0500, Joseph Alotta  
wrote:

>Greetings,
>
>The main program I am working on now is called Books.
>
>If I evaluate
>
>Books allInstances => anOrderedCollection( aBook aBook aBook )
>
>How do I set them all equal to nil like
>
>Books removeAllInstances.
>
>Books allInstances => anOrderedCollection().
>
>
>Sincerely,
>
>Joseph.
-- 
Louis LaBrunda
Keystone Software Corp.
SkypeMe callto://PhotonDemon

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[Newbies] Re: remove allInstances?

[Joseph Alotta]

Nice.  That causes Squeak 5.0 to unexpectedly quit.

But when I start again, there are no instances of Books.

Sincerely,

Joseph



> On Sep 23, 2016, at 7:59 AM, Louis LaBrunda [via Smalltalk] 
>  wrote:
> 
> Books allInstances do: [:b | b become: nil]. 





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RE: [Newbies] Re: remove allInstances?

[Ron Teitelbaum]

Woop woop, alarm alarm, error error.

 

Sorry my alarm just went off.  If Squeak quit after a become and you are
seeing differences after not saving things, something is wrong.  

 

Be afraid, be very afraid.

 

All the best,

 

Ron Teitelbaum

 

From: beginners-boun...@lists.squeakfoundation.org
[mailto:beginners-boun...@lists.squeakfoundation.org] On Behalf Of Joseph
Alotta
Sent: Friday, September 23, 2016 10:15 AM
To: beginners@lists.squeakfoundation.org
Subject: [Newbies] Re: remove allInstances?

 

Nice.  That causes Squeak 5.0 to unexpectedly quit. 

But when I start again, there are no instances of Books. 

Sincerely, 

Joseph 



> On Sep 23, 2016, at 7:59 AM, Louis LaBrunda [via Smalltalk] <[hidden
email]> wrote: 
> 
> Books allInstances do: [:b | b become: nil]. 



  _  

View this message in context: Re: remove allInstances?
 
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  at Nabble.com.

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[Newbies] Re: remove allInstances?

[Joseph Alotta]

maybe they were garbage collected before the crash or on startup.



> On Sep 23, 2016, at 9:23 AM, Ron Teitelbaum [via Smalltalk] 
>  wrote:
> 
> Woop woop, alarm alarm, error error.
> 
>  
> 
> Sorry my alarm just went off.  If Squeak quit after a become and you are 
> seeing differences after not saving things, something is wrong. 
> 
>  
> 
> Be afraid, be very afraid.
> 
>  
> 
> All the best,
> 
>  
> 
> Ron Teitelbaum
> 
>  
> 
> From: [hidden email] [mailto:[hidden email]] On Behalf Of Joseph Alotta
> Sent: Friday, September 23, 2016 10:15 AM
> To: [hidden email]
> Subject: [Newbies] Re: remove allInstances?
> 
>  
> 
> Nice.  That causes Squeak 5.0 to unexpectedly quit. 
> 
> But when I start again, there are no instances of Books. 
> 
> Sincerely, 
> 
> Joseph 
> 
> 
> 
> > On Sep 23, 2016, at 7:59 AM, Louis LaBrunda [via Smalltalk] <[hidden 
> > email]> wrote: 
> > 
> > Books allInstances do: [:b | b become: nil]. 
> 
> 
> View this message in context: Re: remove allInstances?
> Sent from the Squeak - Beginners mailing list archive at Nabble.com.
> 
> 
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Re: [Newbies] remove allInstances?

[Tobias Pape]

Hi,

On 23.09.2016, at 15:03, Louis LaBrunda  wrote:

> Hi Joseph,
> 
> Try:
> 
> Books allInstances do: [:b | b become: nil].

I would advise against that. Become is a sledgehammer and you're about to crush 
ants with it.

What happens with 'a become: b' ? All occurrences of 'a' in the image are 
replaced by 'b' and (this is important) vice versa.
So, all 'b's are replaces by 'a'.

With your example, all occurrences of nil are replaced with an instance of 
Book, in the whole image. This is most probably _not_ what you want.

These two versions work better:

Books allInstances do: [:b | b becomeForward: nil].
Books allInstances do: [:b | b become: Object new].

The first avoids the 'vice versa' part of become: and is more safe, the second 
one
does the switcharoo with a new object every time, wich is also more safe.

Anyhow, I presume that your intent is to track down instances of Book wich you 
don't know where they are.

Maybe they are actually unreferenced already, so
Smalltalk garbageCollect
can get already rid of them. 

If that does not help, you can try to track the references down by doing

Books allInstances do: [:b | b chasePointers]

which will open a PointerFinder for each of the rouge object so you can inspect 
where they get referenced.

I hope this helps.

Best regards
-Tobias


> 
> Lou
> 
> On Fri, 23 Sep 2016 00:40:33 -0500, Joseph Alotta  
> wrote:
> 
>> Greetings,
>> 
>> The main program I am working on now is called Books.
>> 
>> If I evaluate
>> 
>> Books allInstances => anOrderedCollection( aBook aBook aBook )
>> 
>> How do I set them all equal to nil like
>> 
>> Books removeAllInstances.
>> 
>> Books allInstances => anOrderedCollection().
>> 
>> 
>> Sincerely,
>> 
>> Joseph.
> -- 
> Louis LaBrunda
> Keystone Software Corp.
> SkypeMe callto://PhotonDemon
> 
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[Newbies] remove allInstances?

[Louis LaBrunda]

Hi,

Tobias is right.  I'm use to the VA Smalltalk one way #become: and forgot about 
Squeaks two way
#become:, sorry about that.

Lou

On Fri, 23 Sep 2016 19:47:31 +0200, Tobias Pape  wrote:

>Hi,
>
>On 23.09.2016, at 15:03, Louis LaBrunda  wrote:
>
>> Hi Joseph,
>> 
>> Try:
>> 
>> Books allInstances do: [:b | b become: nil].
>
>I would advise against that. Become is a sledgehammer and you're about to 
>crush ants with it.
>
>What happens with 'a become: b' ? All occurrences of 'a' in the image are 
>replaced by 'b' and (this is important) vice versa.
>So, all 'b's are replaces by 'a'.
>
>With your example, all occurrences of nil are replaced with an instance of 
>Book, in the whole image. This is most probably _not_ what you want.
>
>These two versions work better:
>
>Books allInstances do: [:b | b becomeForward: nil].
>Books allInstances do: [:b | b become: Object new].
>
>The first avoids the 'vice versa' part of become: and is more safe, the second 
>one
>does the switcharoo with a new object every time, wich is also more safe.
>
>Anyhow, I presume that your intent is to track down instances of Book wich you 
>don't know where they are.
>
>Maybe they are actually unreferenced already, so
>   Smalltalk garbageCollect
>can get already rid of them. 
>
>If that does not help, you can try to track the references down by doing
>
>   Books allInstances do: [:b | b chasePointers]
>
>which will open a PointerFinder for each of the rouge object so you can 
>inspect where they get referenced.
>
>I hope this helps.
>
>Best regards
>   -Tobias
>
>
>> 
>> Lou
>> 
>> On Fri, 23 Sep 2016 00:40:33 -0500, Joseph Alotta  
>> wrote:
>> 
>>> Greetings,
>>> 
>>> The main program I am working on now is called Books.
>>> 
>>> If I evaluate
>>> 
>>> Books allInstances => anOrderedCollection( aBook aBook aBook )
>>> 
>>> How do I set them all equal to nil like
>>> 
>>> Books removeAllInstances.
>>> 
>>> Books allInstances => anOrderedCollection().
>>> 
>>> 
>>> Sincerely,
>>> 
>>> Joseph.
>> -- 
>> Louis LaBrunda
>> Keystone Software Corp.
>> SkypeMe callto://PhotonDemon
>> 
>> ___
>> Beginners mailing list
>> Beginners@lists.squeakfoundation.org
>> http://lists.squeakfoundation.org/mailman/listinfo/beginners
-- 
Louis LaBrunda
Keystone Software Corp.
SkypeMe callto://PhotonDemon

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