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Re: IDLv5.4

David Fanning wrote:
> Jeffrey Newmark (newmark@eitv2.nascom.nasa.gov) writes:
> > I was wondering if anyone has had problems reading save sets
> > made with IDL V5.4 on older versions? Is this a feature?
> Uh, yes. It has been a feature since IDL 0.934b.
> > I can read old save sets on the new version. If indeed the savesets
> > are not backwards compatible, that is very annoying!
> What can I say. Get used to disappointment. :-)
> Cheers,
> David
> P.S. Let's just say I'm working on a future-looking
> version of IDL that will anticipate all the new features
> in the product up through February 29th, 2043. You
> should see the list!!

Oh, actually some degree of forward compatibility _is_ possible after
all. I recently opened my eyes in amazement when I was able to read a
text document produced with StarOffice 5.2 in the StarOffice 5.1
version. Seems like this would never be possible with MS Word, for
they release new versions every so often specifically to ensure that
the file format changes. 

In terms of the IDL sav files, it should be possible for RSI to create
a file format that is preserved over version changes most of the time,
so that only new features will not be recognized when reading them
into an older version of IDL. In fact, some work on this could open
possibilities for cheap (free?) runtime licenses allowing only
execution of sav files but no pro file compilation or interactive
command line. Right now it seems practically impossible to distribute
applications as sav files because you have to provide one for every
new version (I vaguely remember that sav files are not even backwards
compatible ?). 


[[ Dr. Martin Schultz   Max-Planck-Institut fuer Meteorologie    [[
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