[squeak-dev] Don't rely on weak reference cleanup for lookup of undeclared references

Levente Uzonyi leves at caesar.elte.hu
Tue Jun 5 09:46:39 UTC 2018


Well, Pharo still has #rename: implemented on Class, but it will simply 
break your source code if you use it. Because it'll change the binding to 
the new one, but keep the source code as it was before renaming.

Levente

On Tue, 5 Jun 2018, Levente Uzonyi wrote:

> Pharo uses RB to rename classes. Squeak has not integrated that to the Trunk, 
> so it is not possible to rewrite code using the renamed class just yet, 
> therefore the old binding is kept and stored in Undeclared.
>
> Levente
>
> On Tue, 5 Jun 2018, Max Leske wrote:
>
>> Bump.
>> 
>> 
>>> Hi Eliot,
>>> 
>>> 
>>>  
>>> 
>>> On 28 May 2018 at 22:03:24, squeak-dev-request at lists.squeakfoundation.org 
>>> (squeak-dev-request at lists.squeakfoundation.org) wrote:
>>> 
>>> Hi Max,
>>> 
>>> 
>>>>  On May 27, 2018, at 2:44 PM, Max Leske <maxleske at gmail.com> wrote:
>>>>  
>>>> Hi,
>>>>  
>>>> Once again, there's a situation in the Fuel test suite that uncovered an 
>>>> issue. Consider the following script:
>>>>  
>>>> Object subclass: #Foo
>>>> instanceVariableNames: ''
>>>> classVariableNames: ''
>>>> poolDictionaries: ''
>>>> category: 'Kernel-Classes'.
>>>> 
>>>> 10 timesRepeat: [(Smalltalk at: #Foo) rename: #Bar.
>>>> (Smalltalk at: #Bar) rename: #Foo ]
>>>>  
>>>> In 5.2-alpha this will open a warning dialog, as at some point one of the 
>>>> class names will be undeclared. Class>>rename: only checks for an entry 
>>>> in the undeclared dictionary without considering that the weak references 
>>>> may not yet have been cleaned up.
>>>>  
>>>> I understand that this is not really a realistic real world use-case but 
>>>> it's still annoying for tests. My current workaround is a forced GC after 
>>>> *every* test in the entire suite (I use ClassFactoryForTestCase, so class 
>>>> names may be reused many times over). Luckily, the impact on
>>>> runtime isn't too bad.
>>>>  
>>>> I'd appreciate it if this could be fixed. I'd be even more happy if I 
>>>> could be notified of the fix, so that I can remove the workaround again.
>>> 
>>> Do you have ideas about where the bug lies?
>>> Sort of. In Pharo it seems that when renaming a class, the original class 
>>> name is never added to Undeclared while in Squeak it is. 
>>> 
>>> It looks to me, that the problem is that Environment>>unbind: is never 
>>> sent. In Environment>>renameClass:from:to: #binding:removedFrom: 
>>> undeclares the original class name and #binding:addedTo: adds the new 
>>> binding to the environment. But the now undeclared original class name 
>>> remains undeclared. The following modification gets rid of the problem:
>>>
>>> 	<snip>
>>>
>>> 	aClass updateMethodBindingsTo: newBinding.
>>>
>>> 	declarations add: newBinding. 
>>>
>>> 	self binding: newBinding addedTo: self.
>>>
>>> 	self unbind: oldBinding key. "<---------------------- added"
>>>
>>> 	<snip>
>>> 
>>> 
>>> 
>>> HTH,
>>> 
>>> Max
>>> 
>>> 
>>> 
>>> 
>>>>  
>>>> Cheers,
>>>> Max
>> 
>


More information about the Squeak-dev mailing list