[Question][vw7.x][BASE] -- DependentsCollection is a collection not a set -- why?

> -----Original Message-----
> From: Mark Ballard [mailto:[hidden email]]
> Sent: Wednesday, May 17, 2006 11:25 PM
> To: [hidden email]
> Subject: [Question][vw7.x][BASE] -- DependentsCollection is a
> collection not a set -- why?
>
> In our application ported from vw2.5 to vw7, I recently
> noticed multiple
> updates.  I traced it down to multiple entries of the same
> object in a
> DependentsCollection.
>
> In our vw2.5 version of our application, we had changed the
> behavior of
> DependentsCollection to be a set, but had not ported that
> change to vw7.
>   I now plan to make the change but wonder what in the
> standard system I
> might be breaking.
>
> So, what application or system tool would want to record multiple
> entries of the same object in a DependentsCollection, and why?
>
> Note 1:
>
> The class comment for DependentsCollection reinforces this
> idea that the
> object can be duplicated, but does not explain why.  It says:
>
> "Note that the same dependent may appear more than once in
> the collection."
>
>
> Note 2:
>
> The change is to the method
>
> DependentsCollect >> asDependentWith:
>
> ^(self includes: anObject)
> ifTrue: [self]
> ifFalse: [self copyWith: anObject]
>
>
> instead of just
>
> ^self copyWith: anObject
>
>
>
> --
> [hidden email]
> (503) 627-5890  Desk   (503) 627-1388  Fax
>
>
>

> One argument is ordering of dependents which might be critical. You can
> assure that you are the last dependent notified when you do a
> removeDependent:self and then addDependent: self.
>
> Thomas
>
>
>>-----Original Message-----
>>From: Mark Ballard [mailto:[hidden email]]
>>Sent: Wednesday, May 17, 2006 11:25 PM
>>To: [hidden email]
>>Subject: [Question][vw7.x][BASE] -- DependentsCollection is a
>>collection not a set -- why?
>>
>>In our application ported from vw2.5 to vw7, I recently
>>noticed multiple
>>updates.  I traced it down to multiple entries of the same
>>object in a
>>DependentsCollection.
>>
>>In our vw2.5 version of our application, we had changed the
>>behavior of
>>DependentsCollection to be a set, but had not ported that
>>change to vw7.
>>  I now plan to make the change but wonder what in the
>>standard system I
>>might be breaking.
>>
>>So, what application or system tool would want to record multiple
>>entries of the same object in a DependentsCollection, and why?
>>
>>Note 1:
>>
>>The class comment for DependentsCollection reinforces this
>>idea that the
>>object can be duplicated, but does not explain why.  It says:
>>
>>"Note that the same dependent may appear more than once in
>>the collection."
>>
>>
>>Note 2:
>>
>>The change is to the method
>>
>>DependentsCollect >> asDependentWith:
>>
>> ^(self includes: anObject)
>> ifTrue: [self]
>> ifFalse: [self copyWith: anObject]
>>
>>
>>instead of just
>>
>> ^self copyWith: anObject
>>
>>
>>
>>--
>>[hidden email]
>>(503) 627-5890  Desk   (503) 627-1388  Fax
>>
>>
>>
>
>

> I know ordering of dependents of ObjectMemory was used for system
> startup, so that alone may explain why dependents were not initially
> implemented as a set.  In recent releases, the Subsystem hierarchy broke
> this reliance, but I don't think any effort was made to go through the
> system and find other such reliance on ordering of dependents, so
> suddenly changing to sets might break something.  Even if it doesn't, it
> would be a system override you would have to maintain from release to
> release.
>
> I would recommend finding out where the duplications are being made and
> eliminating the redundancy.  For example, temporarily edit
> Object>>addDependent: as follows:
>
> addDependent: anObject
>     "Add anObject as one of the receiver's dependents. If anObject is
> one of my application classes and it is already a dependent, debug."
>
>     (anObject class == MyClass
>         and: [self myDependents asDependentsAsCollection includes:
> anObject])
>             ifTrue: [self halt].
>     self myDependents: (self myDependents asDependentsWith: anObject).
>     ^anObject
>
> Dave
>
> Mark Ballard wrote:
>
>> Thanks, Thomas.
>>
>> Ordering of dependents is not important in our application.
>>
>> Does anyone know if any application or system tool needs multiple
>> entries in the DependentsCollection or needs to maintain order of
>> dependents?
>>
>> Thomas Brodt wrote:
>>
>>> One argument is ordering of dependents which might be critical. You can
>>> assure that you are the last dependent notified when you do a
>>> removeDependent:self and then addDependent: self.
>>>
>>> Thomas
>>>
>>>
>>>> -----Original Message-----
>>>> From: Mark Ballard [mailto:[hidden email]] Sent: Wednesday,
>>>> May 17, 2006 11:25 PM
>>>> To: [hidden email]
>>>> Subject: [Question][vw7.x][BASE] -- DependentsCollection is a
>>>> collection not a set -- why?
>>>>
>>>> In our application ported from vw2.5 to vw7, I recently noticed
>>>> multiple updates.  I traced it down to multiple entries of the same
>>>> object in a DependentsCollection.
>>>>
>>>> In our vw2.5 version of our application, we had changed the behavior
>>>> of DependentsCollection to be a set, but had not ported that change
>>>> to vw7.  I now plan to make the change but wonder what in the
>>>> standard system I might be breaking.
>>>>
>>>> So, what application or system tool would want to record multiple
>>>> entries of the same object in a DependentsCollection, and why?
>>>>
>>>> Note 1:
>>>>
>>>> The class comment for DependentsCollection reinforces this idea that
>>>> the object can be duplicated, but does not explain why.  It says:
>>>>
>>>> "Note that the same dependent may appear more than once in the
>>>> collection."
>>>>
>>>>
>>>> Note 2:
>>>>
>>>> The change is to the method
>>>>
>>>> DependentsCollect >> asDependentWith:
>>>>
>>>>     ^(self includes: anObject)
>>>>         ifTrue: [self]
>>>>         ifFalse: [self copyWith: anObject]
>>>>
>>>>
>>>> instead of just
>>>>
>>>>     ^self copyWith: anObject
>>>>
>>>>
>>>>
>>>> --
>>>> [hidden email]
>>>> (503) 627-5890  Desk          (503) 627-1388  Fax
>>>>
>>>>
>>>>
>>>
>>>
>>
>>