| Re: removing objects from a container [message #49004 is a reply to message #49000] |
Fri, 09 June 2006 16:38   |
Karl Schultz
Messages: 341
Registered: October 1999
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Senior Member |
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On Fri, 09 Jun 2006 14:08:01 -0400, Ben Tupper wrote:
> Hello,
>
> David - please look out the window at your roses for a few minutes...
>
> I can't quite figure the REMOVE method out. IDLgrROIgroup inherits from
> (eventually) IDL_CONTAINER so the REMOVE method is supposed to work. I
> don't see in the docs that IDLgrROIgroup overrides the method - but
> something is different.
>
>
> IDL> group = OBJ_NEW('IDLgrROIgroup')
> IDL> roi = OBJ_NEW('IDLgrROI')
> IDL> group->Add, roi
> IDL> group->REMOVE, /ALL
> % IDLGRROIGROUP::REMOVE: Incorrect number of arguments.
> % Execution halted at: $MAIN$
> IDL> group->IDL_CONTAINER::REMOVE,/ALL
>
>
> Is this a bug or just a thorn?
>
It looks like a new bug was introduced here in 6.3 while trying to fix
another problem.
The graphic objects have a PARENT property that is managed by the
IDLgrContainer class as graphic objects are added or removed to/from
containers like grModel. IDLgrROIGroup can't subclass from
IDLgrContainer because IDLgrROIGroup inherits from IDLanROIGroup, which
inherits from IDL_Container (IDLanROIGroup does not store displayable
graphic objects) So, IDLgrROIGroup inherits from IDL_Container for its
container functionality, and IDL_Container doesn't manage a PARENT
property.
So, prior to 6.3, the PARENT property of an IDLgrROI was never getting
updated as it was added or removed from an IDLgrROIGroup.
We fixed this bug in 6.3 by updating the PARENT property in the
already-overridden Add method and adding a new override for the Remove
method that would clear the PARENT property when an IDLgrROI object was
removed.
Unfortunately, the form IDLgrROIGroup->Remove, /ALL was not implemented
correctly in the new Remove method. And it probably was not documented
because it was supposed to work exactly like the superclass method.
I'll open a change request and fix this for next release.
The only workaround I can think of for now is:
group->Remove, group->Get(/ALL)
This would work correctly with or without the bug.
If you do
group->IDL_CONTAINER::REMOVE,/ALL
then the PARENT property of all the ROI's that were in the group will be
left referring to the group object. If that doesn't bother you, then this
would be another way to do it, but I don't think it is a good idea, as it
leaves potential dangling object references.
Karl
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