This wisdom deserves to be stored somewhere under the heading "Age of Objects" ;-)

Hans



From: Mariano Martinez Peck [mailto:marianopeck at gmail.com]
Sent: maandag 5 november 2012 14:04
To: Bert Freudenberg
Cc: The general-purpose Squeak developers list
Subject: Re: [squeak-dev] About a object life



On Mon, Nov 5, 2012 at 1:28 PM, Bert Freudenberg <bert at freudenbergs.de<mailto:bert at freudenbergs.de>> wrote:
On 2012-11-03, at 22:45, Mariano Martinez Peck <marianopeck at gmail.com<mailto:marianopeck at gmail.com>> wrote:

> On Sat, Nov 3, 2012 at 3:26 PM, Edgar J. De Cleene <edgardec2005 at gmail.com<mailto:edgardec2005 at gmail.com>> wrote:
>> Folks:
>>
>> I wish know how old a object is.
>>
> The VM can know if an object is in the young or old area. You could modify the VM and make a primitive that answers this (#isYoung: anOop).
What's wrong with the existing primitiveIsYoung? ;)

Sorry, I though we only had #isYoung:  and I forgot we also had the primitiveIsYoung and even the image side message :)


SmalltalkImage current isYoung: true
==> false

SmalltalkImage current isYoung: Object new
==> true


Also, since our GC does not change the order of objects when compacting, you can tell if an object is older than another by enumerating all objects. The oldest ones are of course nil, false, and true (more than 30 years old now):


This is very interesting!!!
Thanks Bert.

(1 to: 20) inject: self someObject into: [:obj :i |
        Transcript show: i; space; show: (obj printString contractTo: 60); cr.
        obj nextObject]
==>
1 nil
2 false
3 true
4 #Processor->a ProcessorScheduler
5 #(#+ 1 #- 1 #< 1 #> 1 #<= 1 #... 1 #new 0 #new: 1 #x 0 #y 0)
6 {Character value: 0 . Charact...$ú . $û . $ü . $ý . $þ . $ÿ}
7 {CompiledMethod . nil . Array...nil . nil . nil . nil . nil}
8 #Transcript->a TranscriptStream ' '
9 #SourceFiles->an ExpandedSour...s/Work/Frank/frank.changes')
10 #Display->DisplayScreen(1920x1200x32)
11 #Sensor->an EventSensor
12 $'
13 $,
14 $-
15 $.
16 $0
17 $;
18 $=
19 $[
20 $_


- Bert -




--
Mariano
http://marianopeck.wordpress.com
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