[Glass] About GsDeployer new doBulkMigrate

[Dale Henrichs]

Mariano,

You are correct, but once you've migrated all of your instances forward,
you don't need the classes in your class history ...

The other thing to watch for when doing bulk migrations is executing code
during the load that might REQUIRE all instances to be migrated ... the
migrations are not done until the end of the load  ... the classic example
is Monticell itself ... back when I was actively finding and fixing bugs in
the Monticello loaders the new methods were being sent to old instances so
i _had_ to migrate during the load ...

As a final comment ... if for some reason you mess up your class history,
it should be possible to rebuild the class history from the instances of
the old class ... while it is something you don't want to do ... it's worth
keeping in mind that it can be done in an emergency:)

Dale


On Wed, Apr 16, 2014 at 12:05 PM, Mariano Martinez Peck <
marianopeck at gmail.com> wrote:

> Hi gemstoners,
>
> I have just finished reading "Chapter 10 - Class Creation, Versions, and
> Instance Migration" but when I was about to start writing some scripts I
> found GsDeployer. I found this very interesting expression: "GsDeployer new
> doBulkMigrate".
>
> I am not 100% sure of what it does, so please confirm if I understand
> correctly:
>
> 1) it searches each class of symbol list of current user that has more
> than 1 in the class history
> 2) it migrates each version of each found class to the last one from the
> history. And this migration is the basic ones... I mean, new instVars in
> new class will be with nil, and old instVars not existing in new class will
> be dropped, etc.
> 3) committs etc..
>
> So...is that correct? If true, then it means that if I don't have any
> specific migration matter (like instVar renaming, or initialize some new
> instvar with some state that depends on old value, etc etc etc), that would
> migrate everything automatically, right?
>
> But...if that's correct...I need to be *very very very* careful in
> executing such a migration since after the migration I will have lost all
> previous class versions and more importantly, I will have lost instVars
> from old classes in the case new class does not define them. Correct?
>
> Thanks in advance,
>
> --
> Mariano
> http://marianopeck.wordpress.com
>
> _______________________________________________
> Glass mailing list
> Glass at lists.gemtalksystems.com
> http://lists.gemtalksystems.com/mailman/listinfo/glass
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.gemtalksystems.com/mailman/private/glass/attachments/20140416/4b1553fb/attachment.html>