Hi Tobias,

On Wed, Jul 6, 2016 at 12:23 AM, Tobias Pape <Das.Linux at gmx.de> wrote:

>
> On 06.07.2016, at 08:17, Eliot Miranda <eliot.miranda at gmail.com> wrote:
>
> > On Tue, Jul 5, 2016 at 10:21 PM, Tobias Pape <Das.Linux at gmx.de> wrote:
> >
> > On 06.07.2016, at 01:13, commits at source.squeak.org wrote:
> >
> > > Eliot Miranda uploaded a new version of System to project The Trunk:
> > > http://source.squeak.org/trunk/System-eem.835.mcz
> > >
> > > ==================== Summary ====================
> > >
> > > Name: System-eem.835
> > > Author: eem
> > > Time: 5 July 2016, 6:13:25.980763 pm
> > > UUID: 44354df1-cecb-414c-a705-daa84b7388dd
> > > Ancestors: System-eem.834
> > >
> > > Fix reading methods from DataStreams on Spur.  Old code used pre-Spur
> numLits header format, and was not 64-bit aware.
> > >
> >
> > Does that mean that pre-Spur methods on datastreams cannot be read in
> Spur images?
> > That would be a bummer…
> >
> > It needs some kind of version stamp on the stream.  Point me to some
> such and we can switch hit.
>
> There is none.
> I would say, we store the data in the format DataStream already know
> (which happens to be
> the Pre-Spur version) and adapt on read. That would ensure backward- and
> forward-compatibility:
>
> - We could still read CMs serialized in pre-spur.
> - We could also read Spur-CMs in pre-spur images.
>
> Ok. -- break --
> I just realized that what you changed was the read part. so no
> problem here. We could change the part to do things differently
> when running on spur or non-spur.
>

The thing is that the two header formats are incompatible.  The old one
allows up to 2^9-1 literals, the new one up to 2^15-1.  So staying with the
old format limits us.  We need some kind of version stamp.  Right now
DataStream and ImageSegment are extremely version-dependent and hence
restrictive formats.  It would be good for someone to revisit them and try
and add some kind of versioning information, preferably supporting backward
compatibility.


>
> Best regards
>         -Tobias
>
>
> >
> >
> > Best regards
> >         -Tobias
> >
> > > =============== Diff against System-eem.834 ===============
> > >
> > > Item was changed:
>
>
>
>
>


-- 
_,,,^..^,,,_
best, Eliot
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