| Re: widget cleanup problem [message #51715 is a reply to message #51682] |
Tue, 05 December 2006 07:50  |
Braedley
Messages: 57
Registered: September 2006
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Member |
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David Fanning wrote:
> Paul van Delst writes:
>
>> I'm having a bit of issue with cleaning up after myself in a widget program.
>>
>> I have a main GUI that, alongside "regular widgets" also contains a bunch of standalone
>> compound widgets. The main GUI info structure and loading looks something like:
>>
>> Info = { Debug : Debug , $
>> cw1Id : cw1Id , $ ; compound widget 1 base id
>> cw2Id : cw2Id , $ ; compound widget 2 base id
>> cw3Id : cw3Id , $ ; compound widget 3 base id
>> .....etc....
>> cwNId : cwNId } ; compound widget N base id
>> InfoPtr = PTR_NEW( Info )
>> WIDGET_CONTROL, tlBaseId, SET_UVALUE = InfoPtr
>>
>> To get a look at the compound widgets info structure I do the following:
>>
>> WIDGET_CONTROL, Info.cw3Id, GET_UVALUE = cw3_InfoPtr
>>
>> My problem is that when an exit event occurs and the cleanup routine is called, the child
>> compound widgets are cleared first so the reference to their top-level-based is gone and I
>> now have dangling pointers.
>>
>> In my main "exit" event handler, all the various compound widget base ids are still valid.
>> However, by the time the "cleanup" routine is called, they are not -- and thus I can't
>> free the info pointers.
>>
>> I wanted the main "cleanup" routine to handle all the child compound widget pointer
>> free'ing. Does it *have* to be done in the main "exit" event handler?
>>
>> I hope my explanation above makes sense.
>
> People here are just entirely too optimistic today!
>
> With these kind of compound widgets, what we usually do
> is use KILL_NOTIFY to assign a callback to the TLB of the
> compound widget. (This isn't really a TLB, but you know
> what I mean.) When that base widget dies, you enter your
> "cleanup" routine for that compound widget. (This means
> you will have to write one for it.) This is where you
> free your pointer.
>
> This is *identical* to the CLEANUP routine you assign to
> the application's TLB, except that you can't (supposedly)
> use KILL_NOTIFY to assign a cleanup routine to a widget that
> is being managed directly by XManager. You have to use the
> CLEANUP keyword on XManager. (I see ITTVIS programmers break
> this rule all the time, so I presume it's not enforced like
> it used to be, but I still teach it this way. And it still
> works.)
>
> Cheers,
>
> David
> --
> David Fanning, Ph.D.
> Fanning Software Consulting, Inc.
> Coyote's Guide to IDL Programming: http://www.dfanning.com/
> Sepore ma de ni thui. ("Perhaps thou speakest truth.")
I have come to realize that I have a similar problem with a compound
widget I created. Some sample code:
pro cw_listSelect_cleanup, id
widget_control, widget_info(id, /child), get_uvalue=state
;pointer cleanup
ptr_free, state.initial_value, state.eding_value
widget_control, /destroy, id
end
function cw_listSelect, parent, value=value, $
uvalue=uvalue, uname=uname, $
sensitive=sensitive, frame=frame, $
title=title, xsize=xsize, ysize=ysize
base=widget_base(parent, col=1, $
uvalue=uvalue, sensitive=sensitive, $
frame=frame, uname=uname, title=title, $
kill_notify='cw_listselect_cleanup', $
pro_set_value='cw_listSelect_set', $
func_get_value='cw_listSelect_get')
label_base=widget_base(base, /row)
if n_elements(title) eq 1 then $
wTitle=widget_label(label_base, value=title)
;some irrelevant code
initial_value=ptr_new(value)
ending_value=ptr_new([''])
move_info={initial_list:initial_list, ending_list:ending_list, $
initial_value:initial_value, ending_value:ending_value}
;some more irrelevant code
widget_control, label_base, set_uvalue=move_info
return, base
end
My problem comes when I try to destroy the widget. I actually do make
it into the cleanup routine, but apparently label_base has already been
destroyed because I get the following error:
WIDGET_CONTROL: Invalid widget identifier: 0.
when I try to get the uvalue. I still want the user to be able to set
a uvalue for this compound widget, so setting the uvalue of base to
move_info won't work. Any suggestions?
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