[great-users] Abort a transformation

[Achim Gädke]

On 23/02/11 05:07, Daniel Balasubramanian wrote:
> Hi Achim,
>
> If I understand correctly, what you're trying to do is exit the transformation based on some condition, such as a pattern match.  Is this correct?  If so, you could use Test/Case blocks.  Insert a Test block, and put a Case block first that tests the condition for termination.  If that Case is true, then don't have any output ports for that Case (use a "Cut" element, too).  Otherwise, control will fall through to the next Case block in which you could just pass the input straight through to the next rule.
>   
Hi Daniel!

Thanks for the answer. I use test blocks as desribed above frequently to
gain the complement of a match.

Unfortunately, this is not what I was aiming to.

Here is an example:
One might expect a forest structure given by a certain kind of
associations in a model. By labeling the objects successively from the
roots of the trees, one gains the tree-membership of each object. If
there are isolated cyclic structures, these objects have these
associations but won't get a label.

The following transformation might ignore these objects, but the
programmer might wish to abort the transformation - because the model
does not make sense.

Cheers, Achim