On 03.02.2014, at 16:01, Frank Shearar <frank.shearar at gmail.com> wrote:

> On 3 February 2014 14:49, Tobias Pape <Das.Linux at gmx.de> wrote:
>> On 03.02.2014, at 15:28, Frank Shearar <frank.shearar at gmail.com> wrote:
>> 
>>> On 3 February 2014 13:48,  <commits at source.squeak.org> wrote:
>>>> A new version of Collections was added to project The Inbox:
>>>> http://source.squeak.org/inbox/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!
>>> 
>>> So this is a basic depth first traversal with cycle protection, yes?
>>> (This pattern seems to crop up _a lot_. Maybe it's worth pulling out
>>> as a separate algorithm?)
>> 
>> Well, there are two such applications:
>> One with an explicit down-handling of a variable (like this)
>> and one with an implicit variable (semi-global)
>>        (Dynamic variable, probably, at least thread-local)
>> 
>> I would like to have both.
>> I propose the (seaside-inspired) #use:during: message for the second.
> 
> Except that DynamicVariable's #use:during: is incompatible with
> stack-slicing, because those kinds of dynamic variables aren't
> delimited. (Unlike resumable exceptions, for instance.

Sorry, I (currently) don’t know what you mean by stack-slicing.
Are we speaking of Martin von Löwis’ DynamicVariables currently in 4.5/trunk
that are based on Thread-local storage
or the Seaside ones based on Exceptions?

(I just see that DV is using #value:during: rather than #use:during:
the former is consistent while the latter IMHO speaks better)


>> However I cannot imagine a generic message for the first variant.
> 
> myArray depthFirstDo: [:each | each doSomething] havingVisited:
> IdentitySet new ?

Sounds squeakish :)

Best
	-Tobias
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