On Sat, 11 Jan 2014, Levente Uzonyi wrote:

> On Fri, 10 Jan 2014, Colin Putney wrote:
>
>> 
>> 
>> 
>> On Fri, Jan 10, 2014 at 5:32 PM, Eliot Miranda <eliot.miranda at gmail.com> 
>> wrote:
>>  
>>       1) Why isn't the sentinel object enumerated in a shrunken image?
>> 
>> send me an image poised at the right point and I'll take a look...
>> 
>> 
>> While working on creating this image, I noticed that Bert was right. There 
>> is a #becomeForward: happening inside the block that's passed into 
>> #allObjectsDo:. It's because #allObjectsDo: is called from
>> #obsoleteBehaviors, which sends #isBehavior to all the objects. If the 
>> image happens to contain an instance of MCInfoProxy, the DNU causes it to 
>> download the full ancestry and become it. 
>> 
>> However, I don't see why that would cause the sentinel object not to be 
>> enumerated. 
>
> Because #nextObject will be sent to an object which was created after the 
> sentinel.

Now I see why it wasn't clear. For performance reasons #become* methods
don't move the objects around, they just rewrite the pointers pointing to 
them. Here's an example:

a := { $a }.
b := { $b }.
c := { $c }.
self assert: a nextObject == b.
self assert: b nextObject == c.
b become: c.
self assert: a nextObject = #($b).
self assert: b = #($c).
self assert: c = #($b).
self assert: a nextObject == c.
self assert: c nextObject == b.

I think it might help in this case, to ask for the next object before 
evaluating the block in the loop of #allObjectsDo:

 	[lastObject == object]
 		whileFalse: [
 			| nextObject |
 			nextObject := object nextObject.
 			aBlock value: object.
 			object := nextObject]


Levente

>
>
> Levente
>
>> 
>> Colin
>> 
>