On Tue, 17 Nov 2009, Ralph Johnson wrote:

> On Mon, Nov 16, 2009 at 7:11 PM, Levente Uzonyi <leves at elte.hu> wrote:
>> Hi,
>>
>> Round #1 was mostly about sets containing nil, and the winner seems to be
>> the object-oriented solution implemented by Igor:
>> http://bugs.squeak.org/file_download.php?file_id=3829&type=bug
>>
>> What about the other ideas?
>>
>> - create a common superclass (HashedCollection) for Set and Dictionary
>
> I think a better solution is to give Set and Dictionary a common
> component, a HashTable.  I've seen this done several times and it
> always resulted in a clean design.  The major drawback is that
> MethodDictionary doesn't fit that design, and the VM needs to know the
> format of MethodDictionary.

I've been thinking about this a lot before I uploaded the latest changes, 
but I came to a decision that if were using encapsulation instead of 
inheritance, we would have to duplicate the common interface methods. Also 
performance would be worse (extra message sends) mainly because HashTable 
would have to behave differently in Set and Dictionary. So I decided to 
sacrifice a bit of clarity for simplicity and performance.

Levente

>
> -Ralph
>
>