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Re: How to traverse/inquire a class object structure in IDL? [message #17392 is a reply to message #17387]

Wed, 13 October 1999 00:00

Pavel Romashkin
Messages: 166
Registered: April 1999

Senior Member

Paul,
I see no flaw (at least on my programming level) in what you did. Why can't you
just do the loop 13 times (this is the number of fields in your object structure,
and it will never change since it is a named structure)? The method is tied to the
type and 13 will always be OK, unless you are trying to write a generic method.
If you want a generic method (that would wipe out pointers in any
pointer-containing class), there is one way I saw it could be done. If you call
"help, self, /object, /output=report" inside the cleanup method, then it returns
also local information on the instance of that object, for example (I made a new
method called "names"):

a -> names
** Object class NASTI, 0 direct superclasses, 1 known method
Known Procedure Methods:
NASTI::NAMES
Instance Data:
** Structure NASTI, 13 tags, length=52:
WAVENUMBER POINTER <NullPointer>
RADIANCE POINTER <NullPointer>
ALTITUDE POINTER <NullPointer>
FOV_ANGLE POINTER <NullPointer>
FOV_INDEX POINTER <NullPointer>
LATITUDE POINTER <NullPointer>
LONGITUDE POINTER <NullPointer>
AIRCRAFT_ROLL POINTER <NullPointer>
AIRCRAFT_PITCH POINTER <NullPointer>
SCAN_LINE_INDEX POINTER <NullPointer>
DATE POINTER <NullPointer>
TIME POINTER <NullPointer>
DECIMAL_TIME POINTER <NullPointer>

Then you could programmatically inspect REPORT and find the number of tags in the
object instance. Then, clean it up with a loop, checking for the type of the field
being a pointer "if size(self.(i), /type) eq 10 then ptr_free, self.(i)".
I don't use objects of my own; so far I was happy with those IDL comes with. So,
don't blame me if my approach is awkward. I just tried to come up with a solution.
Maybe pros like David can give a much more elegant solution.
Good luck,
Pavel

> Not good. As more objects are created and destroyed, the valid pointer list
> grows. I would like to do the following in a CLEANUP method:
>
> FOR i = 0, n_object_structure_elements - 1 DO $
> IF ( PTR_VALID( self.(i) ) ) THEN $
> PTR_FREE, self.(i)
>
> that is, *explicitly* free up the pointers. This works great if I have a value
> for n_object_structure_elements.

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[Message index]

		Re: How to traverse/inquire a class object structure in IDL? By: davidf on Wed, 13 October 1999 00:00
		Re: How to traverse/inquire a class object structure in IDL? By: Paul van Delst on Wed, 13 October 1999 00:00
		Re: How to traverse/inquire a class object structure in IDL? By: Pavel Romashkin on Wed, 13 October 1999 00:00
		Re: How to traverse/inquire a class object structure in IDL? By: davidf on Wed, 13 October 1999 00:00
		Re: How to traverse/inquire a class object structure in IDL? By: Pavel Romashkin on Wed, 13 October 1999 00:00
		Re: How to traverse/inquire a class object structure in IDL? By: Pavel Romashkin on Wed, 13 October 1999 00:00
		Re: How to traverse/inquire a class object structure in IDL? By: davidf on Wed, 13 October 1999 00:00

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