[Glass] isBytes for fixed pointers but superclass with bytes

[Richard Sargent via Glass]

On Tue, Sep 2, 2014 at 10:47 AM, Mariano Martinez Peck <
marianopeck at gmail.com> wrote:

>
>
>
> On Tue, Sep 2, 2014 at 1:41 PM, Richard Sargent via Glass <
> glass at lists.gemtalksystems.com> wrote:
>
>> GLASS mailing list wrote
>> > In pharo, we don't have a class defined as "fixed pointers" with a
>> "bytes"
>> > superclass. The following expression is empty in Pharo:
>> >
>> > Smalltalk allClasses select: [ :each | (each isBytes and: [ each
>> > allSubclasses size > 0 ])
>> > and: [ each allSubclasses anySatisfy:  [ :aSubClass | aSubClass isBytes
>> > not
>> >  ] ]
>> >  ]
>> >
>> > But in GemStone I have 2 exceptions:
>> >
>> > anArray( AbstractCharacter, Float)
>> >
>> > To me...it looks very strange that, for example, SmallDouble answers
>> false
>> > to #isBytes. So I wonder.....since these are very strange scenarios, as
>> a
>> > simple workaround, could we implement the correct #isBytes, #isVariable
>> > etc
>> > for those particular subclasses?
>>
>> implementationFormat
>>
>> "Returns the three least-significant bits of the receiver's format
>> instance
>>  variable.  The values of those bits mean the following:
>>
>>  0   OOP       non-indexable
>>  1   Byte      non-indexable
>>  2   NSC       non-indexable
>>  3   Special   non-indexable
>>  4   OOP       indexable
>>  5   Byte      indexable"
>>
>> ^ format bitAnd: 16r7
>>
>>
>> If you inspect the format of these classes, you will see they are
>> specials.
>> Their oop fully defines each object. Questions like #isBytes is more
>> meaningful (and useful) when addressed to things like collections.
>>
>>
>>
> Thanks Richard, #implementationFormat was useful. Now I have a doubt with
> NSC. They answer true to #isVariable. However, I cannot seem to find a way
> to iterate its "variable" (not regular pointer slots). For example, in
> Pharo, I can do:
>
> 1 to: anObject basicSize
> do: [ :index | aBlock value: (anObject basicAt: index) ]
>  How can I do that for a NSC, say Bag? Do I need to iterate it's instVars
> as a regular OOP non-indexeable?  (instVarNames...etc...).
>

A Non-sequenceable Collection (NSC) is represented by internal GemStone
data structures. It's instance variables won't get you anywhere. It looks
like you will need to use #do: and just iterate over its contents.


> Thanks,
>
>
>
>
>
>
>
>>
>>
>> --
>> View this message in context:
>> http://forum.world.st/Glass-isBytes-for-fixed-pointers-but-superclass-with-bytes-tp4775703p4775819.html
>> Sent from the GLASS mailing list archive at Nabble.com.
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>
>
>
> --
> Mariano
> http://marianopeck.wordpress.com
>
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