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http://issues.ops4j.org/browse/QI-221?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13310#action_13310
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Rickard Öberg commented on QI-221:
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No, not implemented in the domain model. When the calls reach the domain model
it's already "too late". Once the calls go through the domain model there would
typically be no way to undo/redo, not in the general case anyway. What you'd
want instead is to work with values representing the domain state, and then do
redo/undo on that state, until you decide to commit, or "save", which will
execute the changes in the domain model and after which you cannot undo/redo
again.
If that is the assumed model, then it becomes easier because values are
immutable. So whenever the client wants to change something it actually has to
create a mutable copy of the state, and so you don't have to keep track of what
methods do what, just the references to versions of the values you want to
undo/redo operations on.
Does that make sense to you?
Again: once the calls reach the actual domain model, that's that. You can't
undo that. Something that has happened, has happened. But, building up the list
of changes to perform on the domain model is still "in the air", and can hence
support undo/redo. And if based on values, it becomes even more natural as each
operation will be creating a new copy of the values, since values are immutable.
> Check nested UnitOfWork code so that it works properly.
> -------------------------------------------------------
>
> Key: QI-221
> URL: http://issues.ops4j.org/browse/QI-221
> Project: Qi4j
> Issue Type: Bug
> Reporter: Rickard Öberg
> Assignee: Rickard Öberg
> Priority: Critical
> Fix For: 1.0
>
>
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