On 19 July 2012 00:46, David T. Lewis <lewis at mail.msen.com> wrote:
> On Wed, Jul 18, 2012 at 02:33:23PM -0700, Bert Freudenberg wrote:
>> On 18.07.2012, at 14:08, Frank Shearar wrote:
>>
>> > Is there any particular reason why we don't have OrderedCollection >>
>> > #asOrderedCollection simply return self?
>> >
>>
>> > Right now (OrderedCollection with: 1) asOrderedCollection calls
>> > Collection >> #asOrderedCollection, which calls self as:
>> > OrderedCollection, which copies the collection.
>> >
>> > This would also make OrderedCollection work a bit more like Array -
>> > Array >> #asArray simply returns self.
>> >
>> > frank
>>
>>
>> Here's my guess:
>>
>> The typical use cases for asOrderedCollection and asArray are different. If you send asOrderedCollection you probably want to add more objects to it. If you send asArray you normally won't modify the result.
>>
>> So in a way, you could see asOrderedCollection as the normal "safe" case which ensures the original is unmodified, and the asArray behavior as an optimization.
>>
>> - Bert -
>>
>
> It also ensures that subclasses respond reasonably to #asOrderedCollection.
> For example, if you send #asOrderedCollection to a WeakOrderedCollection
> or a SortedCollection, it is probably because you actually want to obtain
> an OrderedCollection:
>
> (WeakOrderedCollection withAll: #(1 2 3 4)) asOrderedCollection
>      ==> an OrderedCollection(1 2 3 4)
>
> (SortedCollection withAll: #(4 2 3 1)) asOrderedCollection
>      ==> an OrderedCollection(1 2 3 4)

OK, but that's neither here nor there, because those could convert
themselves with #as:.

Levente nailed what surprised me, but that might well be only because
I had just read Array >> #asArray. 'as' implies conversion which, in
_my_ head means 'only convert if necessary'. But this change does have
the potential to break many things in very bad ways, as OCs that were
copies (so safe from mutation) suddenly aren't.

Those kinds of bugs will be hard to decipher, so maybe it's better
just to leave the method unchanged and hold my nose.

frank

> Dave
>
>