[Glass] isBytes for fixed pointers but superclass with bytes

[Mariano Martinez Peck via Glass]

On Tue, Sep 2, 2014 at 3:13 PM, Richard Sargent <
richard.sargent at gemtalksystems.com> wrote:

> 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.
>
>
OK, that did the trick.
Thanks for the help.


>
>> 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.
>>> _______________________________________________
>>> Glass mailing list
>>> Glass at lists.gemtalksystems.com
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>>>
>>
>>
>>
>> --
>> Mariano
>> http://marianopeck.wordpress.com
>>
>
>


-- 
Mariano
http://marianopeck.wordpress.com
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