On 3 February 2014 16:58, Chris Muller <asqueaker at gmail.com> wrote:
> Well, I don't much like it.  Remember our discussion a couple of
> months ago, we were wondering whether LRUCache was even useful at all?
>  Granted, Levente said the prior _implementation_ was not useful,
> which he addressed with this new one.
>
> But now what was once a simple and fast check in Array>>#isLiteral now
> allocates an IdentityDictionary every time, just to accomodate this
> strange implementation of LRUCache.

You mean "just to fix broken behaviour which relied on certain
unstated assumptions being true to avoid crashing horribly" :)
#isLiteral was a bit naive, but I suppose it's not so obvious a danger
as a cons cell.

But anyway, this is why I wondered about writing a more general
solution. For instance, writing a DepthFirstfTraversal that explicitly
was safe against cyclic structures.

> And still leaves open other potential infinite-recursions.

Like? It remembers which nodes it's visited.

frank

> So, I see this as having some of the same properties as the effing
> MCInfoProxy's in that we may find we need to patch Array (!!) at some
> point in the future again -- If any other method besides #isLiteral in
> Array, ArrayedCollection, SequenceableCollection, Collection, Object,
> or ProtoObject happens to invoke a recursive function like #isLiteral
> did, we're hosed.  (and yet, no complaints from anyone in the
> community, hmm how ironic..)
>
>
> On Mon, Feb 3, 2014 at 10:28 AM, Frank Shearar <frank.shearar at gmail.com> wrote:
>> On 3 February 2014 16:18,  <commits at source.squeak.org> wrote:
>>> Chris Muller uploaded a new version of Collections to project The Trunk:
>>> http://source.squeak.org/trunk/Collections-ul.564.mcz
>>>
>>> ==================== Summary ====================
>>>
>>> Name: Collections-ul.564
>>> Author: ul
>>> Time: 3 February 2014, 2:35:36.802 pm
>>> UUID: 4b9a37ef-df86-40a0-a0dd-8e8b2c04d4ed
>>> Ancestors: Collections-ul.563
>>>
>>> Make sure that Array >> #isLiteral won't get into an infinite recursion, even if the receiver has an recursive structure.
>>>
>>> =============== Diff against Collections-ul.563 ===============
>>>
>>> Item was changed:
>>>   ----- Method: Array>>isLiteral (in category 'testing') -----
>>>   isLiteral
>>> +
>>> +       ^self class == Array and: [
>>> +               self isLiteralIfContainedBy: IdentitySet new ]!
>>> -       ^self class == Array and: [self allSatisfy: [:each | each isLiteral]]!
>>>
>>> Item was added:
>>> + ----- Method: Array>>isLiteralIfContainedBy: (in category 'testing') -----
>>> + isLiteralIfContainedBy: parents
>>> +       " Answer whether the receiver has a literal text form recognized by the compiler. Precondition: the receiver is an instance of Array. "
>>> +
>>> +       (parents includes: self) ifTrue: [ ^false ].
>>> +       parents add: self.
>>> +       1 to: self size do: [ :index |
>>> +               | element |
>>> +               element := self at: index.
>>> +               (element class == Array
>>> +                       ifTrue: [ element isLiteralIfContainedBy: parents ]
>>> +                       ifFalse: [ element isLiteral ]) ifFalse: [ ^false ] ].
>>> +       parents remove: self.
>>> +       ^true!
>>
>> +1
>>
>> frank
>>
>