comp.lang.idl-pvwave archive: archive » Re: How to traverse/inquire a class object structure in IDL?

Home » Public Forums » archive » Re: How to traverse/inquire a class object structure in IDL?

Show: Today's Messages :: Show Polls :: Message Navigator
E-mail to friend

Re: How to traverse/inquire a class object structure in IDL? [message #17388 is a reply to message #17387]

Wed, 13 October 1999 00:00

Paul van Delst
Messages: 364
Registered: March 1997

Senior Member

First off, thanks to David and Pavel for their insights. Before I could check the
newsgroup for replies, one of our younger go-getter science types came and told me
something about object oriented programming that made good sense:

The data should be an attribute of the object, not the object itself.

Hmm. Anyway, he and I sat down for about 15 minutes and came up with the following
class structure definition and cleanup method:

PRO nasti__define

; -- Define the NAMED data structure attribute
data = { data, $
wavenumber : PTR_NEW(), $
radiance : PTR_NEW(), $
altitude : PTR_NEW(), $
fov_angle : PTR_NEW(), $
fov_index : PTR_NEW(), $
latitude : PTR_NEW(), $
longitude : PTR_NEW(), $
aircraft_roll : PTR_NEW(), $
aircraft_pitch : PTR_NEW(), $
scan_line_index : PTR_NEW(), $
date : PTR_NEW(), $
time : PTR_NEW(), $
decimal_time : PTR_NEW() }

; -- Create object CLASS structure
nasti = { nasti, $
data : data }

END

I like this becuase now I can add additional attributes whenever I want, e.g.
global attribute data read from the netCDF data file containing instrument
calibration information and/or processing software CVS/RCS info etc.

The cleanup method is now:

PRO nasti::cleanup

PRINT, FORMAT = '( /5x, "Clean up..." )'

; -- Free up pointers
n_data_fields = N_TAGS( self.data )
FOR i = 0, n_data_fields - 1 DO $
IF ( PTR_VALID( self.data.(i) ) ) THEN $
PTR_FREE, self.data.(i)

END

I just couldn't bring myself to typing PTR_FREE, self.whatever a bunch of times
because if I ever change the data structure definition, I would have to change the
cleanup as well. I like changes in my code to have as small a footprint as
possible, i.e. change is required in as few places as possible. Dunno if that's a
great idea but for my simple little example but it's a start. Right?

I wish I'd "discovered" objects earlier......all that code I wrote that *needs* the
data to be encapsulated. Crikey.

Thanks again!

paulv

--
Paul van Delst
Space Science and Engineering Center | Ph/Fax: (608) 265-5357, 262-5974
University of Wisconsin-Madison | Email: paul.vandelst@ssec.wisc.edu
1225 W. Dayton St., Madison WI 53706 | Web: http://airs2.ssec.wisc.edu/~paulv

Report message to a moderator

[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

Previous Topic:	polyfill on a map
Next Topic:	IDL and KDE

-=] Back to Top [=-

[ Syndicate this forum (XML) ] [

] [

]

Current Time: Mon Dec 01 06:56:48 PST 2025

Total time taken to generate the page: 0.56262 seconds