[squeak-dev] Producing alpha images

Keith Hodges keith_hodges at yahoo.co.uk
Wed Dec 10 05:10:29 UTC 2008


Andreas Raab wrote:
> Hi Keith -
>
> Keith Hodges wrote:
>> Edgar has delivered image after image, but does that help anyone in the
>> long run really. It  doesn't help me. I have production code and I don't
>> have time to spend a month moving it form one image to another manually,
>> without any tools to help, broken MC, broken Universes etc. It doesnt
>> help us move forward in the future to something like Morphic 3.0, or COG
>> for which atomic loading is likely to be essential.
>
> There is only one way to answer your question: YES!!! It *does* help
> to produce alpha images.
I didn't say there was anything wrong with alpha images. What I said was
that an alpha image doesn't help me with the integration process, if I
have legacy code.

If I change an API in 3.11, and I have a package version I am developing
in 3.11, I will break all the code that relies on the new API, and my
package will not work for those on older images. Clients of my package
will have to stick with the old version of my package until they get to
the image transition point, and then they will have to port to my new
version.

However if I have a place in the framework to publish the new api for
older images, then this allows my package to continue to be supported in
older images even though it is using the upto date api.

The clients can keep up to date with my changes to my package, and when
it comes to transitioning to a new image, there is nothing required for
it to work.

This is what LevelPlayingField does. So I am simply proposing that an
alpha image without thought for a compatability layer is r&d.

Keith



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