Hi,
I think that the problem occurs iff a garbage collect/finalization occurs during
the DependentsArray>>copyWith: .

This code exhibits the problem that you describe...

     d := (DependentsArray new: 1).
     1 to: 50 do:[:i |
        d := d copyWith: Object new ].

whereas this code runs without error....

    d := (DependentsArray new: 1).
    1 to: 50 do:[:i |
          Smalltalk garbageCollect.
          d := d copyWith: Object new ].

I have also seen this problem when using Smacc, but didn't solve the root cause
of the problem. I just did a garbage collect before generating the
parser/scanner and the problem went away.

Hope this helps.
Cheers,
Andy



----- Original Message ----- 
From: "mathieu" <mathk.sue at gmail.com>
To: <ncellier at ifrance.com>; "The general-purpose Squeak developers list"
<squeak-dev at lists.squeakfoundation.org>
Sent: Thursday, July 20, 2006 6:49 AM
Subject: Re: DependentsArray size and subscript is out of bounds


> nicolas cellier a écrit :
> > Le Jeudi 20 Juillet 2006 00:38, mathieu a écrit :
> >> Hi,
> >>
> >> It is normal that:
> >>
> >> (DependentsArray new: 100) size
> >>
> >> return 0?
> >
> > Yes
> >
> >> If yes so why?
> >
> > DependentsArray count only non nil elements
> >
> >> And if I do:
> >> | o |
> >>
> >> o := WriteStream on: (DependentsArray new: 100).
> >> 1 to: 24 do: [:each | o nextPut: Object new]. "do it sevral time"
> >>
> >> it raise an error 'subscript is out of bounds: 22' from time to time
> >> why?
> >
> > You cannot do that with DependentsArray.
> >
> > DependentsArray are weak array: that mean that storing an object into a
> > DependentsArray does not prevent it from being garbageCollected.
> >
> > When an element is garbage collected, corresponding index in DependentsArray
> > is replaced by nil.
> >
> > All is occuring in pastEndPut:
> > Since initial size (non nil elements) is zero, then the array is grown to
> > size: oldSize + ((oldSize max: 20) min: 1000000)
> >
> > When no garbageCollection occurs, that works fine (except a new
> > DependentsArray is created each time you add an Object).
> >
> > When a garbage collect occurs, all unreferenced (Object new) are removed
from
> > the DependentsArray, except one (I do not know who is referencing it, maybe
> > the BlockContext...).
> >
> > Thus you allocate a DependentsArray of size 21 and fail when storing element
> > number 22...
> >
> >> Thx
> >> Math
> >
> > What do you need DependentsArray for?
> >
> > Nicolas
>
> ok thx :)
>
> In fact this is "used" in SmaCC and raise this error:
>
> ======================================================
> DependentsArray(Object)>>error:
> Receiver: a DependentsArray(<keyword> ")" "]" <binarySymbol> "}" ";"
> <period> ">" <name> E O F)
> Arguments and temporary variables:
> aString: *'subscript is out of bounds: 23'*
> Receiver's instance variables:
> a DependentsArray(<keyword> ")" "]" <binarySymbol> "}" ";" <period> ">"
> <name> E O F)
>
> DependentsArray(Object)>>errorSubscriptBounds:
> Receiver: a DependentsArray(<keyword> ")" "]" <binarySymbol> "}" ";"
> <period> ">" <name> E O F)
> Arguments and temporary variables:
> index: 23
> Receiver's instance variables:
> a DependentsArray(<keyword> ")" "]" <binarySymbol> "}" ";" <period> ">"
> <name> E O F)
>
> DependentsArray(Object)>>at:put:
> Receiver: a DependentsArray(<keyword> ")" "]" <binarySymbol> "}" ";"
> <period> ">" <name> E O F)
> Arguments and temporary variables:
> index: 23
> value:
> Receiver's instance variables:
> a DependentsArray(<keyword> ")" "]" <binarySymbol> "}" ";" <period> ">"
> <name> E O F)
>
> WriteStream>>pastEndPut:
> Receiver: <<error during printing>>
> Arguments and temporary variables:
> anObject:
> oldSize: 2
> grownCollection: a DependentsArray(<keyword> ")" "]" <binarySymbol>
> "}" ";" <pe...etc...
> Receiver's instance variables:
> collection: a DependentsArray(<keyword> ")" "]" <binarySymbol> "}"
> ";" <period>...etc...
> position: 23
> readLimit: 23
> writeLimit: 1
>
>
> --- The full stack ---
> DependentsArray(Object)>>error:
> DependentsArray(Object)>>errorSubscriptBounds:
> DependentsArray(Object)>>at:put:
> WriteStream>>pastEndPut:
>  - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
> WriteStream>>nextPut:
> [] in DependentsArray>>copyWith: {[:s |  self   do: [:item | s nextPut:
> item].  s nextPut: newElement]}
> DependentsArray class(SequenceableCollection class)>>streamContents:
> DependentsArray>>copyWith:
> DependentsArray(Array)>>copyWithDependent:
> SmaCCSymbolSet(Object)>>addDependent:
> SmaCCSymbolSet>>addComponent:
> SmaCCSymbolSet>>baseOn:
> SmaCCSymbolSet class>>basedOn:
> SmaCCLR1Item>>moveNext
> [] in SmaCCItemSet>>moveOn: {[:each | each nextSymbol == aGrammarSymbol
>   ifTrue: [anItemSet add: each mo...]}
> SmaCCItemSet(Set)>>do:
> SmaCCItemSet>>moveOn:
> [] in SmaCCGrammarCompiler>>createItemSets {[:each |  newState :=
> itemSet moveOn: each.  newState notEmpty   ifTrue: [sh...]}
> SortedCollection(OrderedCollection)>>do:
> SmaCCGrammarCompiler>>createItemSets
> SmaCCGrammarCompiler>>transitionTable
> SmaCCGrammarCompiler>>compileTransitionTable
> SmaCCGrammarCompiler>>compileParser
> SmaCCGrammarCompiler>>createChanges
> ======================================================
>
>
>
>