| Re: widget cleanup problem [message #51681] |
Tue, 28 November 2006 12:10  |
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Paul Van Delst[1]
Messages: 1157
Registered: April 2002
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Senior 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.
You're brilliant, you are.
> 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.)
I actually already had all the various cleanup routines - when i write widget code my
fingers just type out the code on their own. I just didn't know how to invoke it.
Bloody beautiful. My widget proggy works, the aussies won the first test. It's been a good
week so far. :o)
cheers,
paulv
--
Paul van Delst Ride lots.
CIMSS @ NOAA/NCEP/EMC Eddy Merckx
Ph: (301)763-8000 x7748
Fax:(301)763-8545
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