Ticket #555 (closed enhancement: fixed)
Opened 2011-06-01T15:28:08-05:00
Last modified 2011-06-07T17:26:10-05:00
Convention for how a plugin handles no image/view selected
| Reported by: | gharris | Owned by: | curtis |
|---|---|---|---|
| Priority: | major | Milestone: |
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| Component: | Plugin Framework | Version: | |
| Severity: | serious | Keywords: | |
| Cc: | Blocked By: | ||
| Blocking: |
Description
If the plugin relies on there being a view selected, it may do this in its constructor:
final AbstractDatasetView view = getActiveDisplayView();
And then if no view exists, referencing view throws NullPointer exception.
Change History
comment:1 Changed 2011-06-01T15:36:29-05:00 by curtis
comment:2 Changed 2011-06-01T16:13:54-05:00 by gharris
I like it (at least as the short-term.)
Ideally we will have an encoding of the conditions in such a way that the actions can be enabled/disabled based on selection...
comment:3 Changed 2011-06-07T17:26:10-05:00 by curtis
- Status changed from new to closed
- Resolution set to fixed
Rather than a companion interface, as of 14f53919701b09367691844cfe1cf9dd2202b9b9 it is possible for a plugin preprocessor to provide a message indicating a reason for cancelation. This message is propagated through the system. Specifically, at the PluginRunner level it becomes a warning-style StatusEvent that the Swing UI displays to the end user in a dialog box.
We will still need a solution in the long term to query a plugin for whether the current context is acceptable to execution.
One solution could be to have a companion interface (similar to PreviewPlugin) called ConditionalPlugin with a "String checkConditions()" method that verifies the current program state is acceptable to execution. In the example above, this method would check if view!=null, returning null if so. If the conditions fail, the method returns a string error message explaining why the plugin cannot be executed. The plugin UI framework can then display a modal dialog box with the error message, if the conditions are not met.