| Re: Object definition [message #20526] |
Sun, 09 July 2000 00:00 |
John-David T. Smith
Messages: 384
Registered: January 2000
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Senior Member |
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Any named structure (of the both the regular and object-class-defining
varieties) which IDL doesn't know about will cause a search on the path for a
defining procedure "name__define.pro". We take this functionality for
granted... so much so that various confusing things can happen when it is
circumvented (e.g. by restoring an object or named structure).
JD
--
J.D. Smith |*| WORK: (607) 255-5842
Cornell University Dept. of Astronomy |*| (607) 255-6263
304 Space Sciences Bldg. |*| FAX: (607) 255-5875
Ithaca, NY 14853 |*|
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| Re: Object definition [message #20536 is a reply to message #20526] |
Fri, 07 July 2000 00:00  |
davidf
Messages: 2866
Registered: September 1996
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Senior Member |
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Pavel Romashkin (promashkin@cmdl.noaa.gov) writes:
> I did not realize that HELP will call definition method without me
> creating an object instance first.
Well, assuming you have written the object definition
module correctly and given it and the file the correct
name. Which, since it is you, Pavel, I feel certain
is the case. :-)
Cheers,
David
P.S. Let's just say without Automatic Structure Definitions
it would be impossible to implement objects as named
structures, without (Heaven forbid) having to manually
compile them first. :-)
--
David Fanning, Ph.D.
Fanning Software Consulting
Phone: 970-221-0438 E-Mail: davidf@dfanning.com
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Toll-Free IDL Book Orders: 1-888-461-0155
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| Re: Object definition [message #20537 is a reply to message #20536] |
Fri, 07 July 2000 00:00 |
promashkin
Messages: 169
Registered: December 1999
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Senior Member |
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I guess I understand it now. Named structures are not retained after
session is over. If a named structure is defined as a variable, its
definition and name are gone after a session reset (or IDL quit).
However, for object definitions, executing "HELP, {my_obj}, /obj" in
fact calls the object definition code "my_obj__define" and creates a
blank instance of that object for HELP to use. Then, HELP returns info
on blank object instance. But, for a variable that contained a named
structure, such call results in the message:
% Attempt to call undefined procedure/function: 'TEMP__DEFINE'.
% Structure type not defined: TEMP.
Just as expected.
I did not realize that HELP will call definition method without me
creating an object instance first.
Cheers,
Pavel
Ben Tupper wrote:
> It is expected (at least I expect) the named structure to be retained
> from session to session. When I start-up a new session,
> I can do as you describe, HELP, {temp}, /Str and get output of all of the
> fields. The pointers are all null-pointers and the
> other fields are as I defined them in the Temp__Define procedure.
>
> I think you are describing a different behavior and I'm not clear on what
> the behavior is. As an example, it sounds like you might have defined a
> string field in the temp__DEFINE procedure as Temp.Name = ''. Later
> you did something like oTemp->SetProperty, Name = 'PAVEL'. Then you
> quit (or reset). Doing the Help, {Temp},Str shows Temp.Name =
> 'PAVEL'. Am I getting that right?g
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| Re: Object definition [message #20541 is a reply to message #20536] |
Fri, 07 July 2000 00:00 |
Ben Tupper
Messages: 186
Registered: August 1999
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Senior Member |
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Pavel Romashkin wrote:
> When I define an object (user-defined), there, of course, is a named
> structure named, lets say, "temp". So I can call "help, {temp}" to see
> what the fields are. Then, I reset IDL or even quit it. Then, start it
> again and type "help, {temp}" again - the information is printed out
> about the last state of the structure! Strange.
> I use 5.3 on a Mac.
> Thanks for any input.
> Pavel
Hello,
It is expected (at least I expect) the named structure to be retained
from session to session. When I start-up a new session,
I can do as you describe, HELP, {temp}, /Str and get output of all of the
fields. The pointers are all null-pointers and the
other fields are as I defined them in the Temp__Define procedure.
I think you are describing a different behavior and I'm not clear on what
the behavior is. As an example, it sounds like you might have defined a
string field in the temp__DEFINE procedure as Temp.Name = ''. Later
you did something like oTemp->SetProperty, Name = 'PAVEL'. Then you
quit (or reset). Doing the Help, {Temp},Str shows Temp.Name =
'PAVEL'. Am I getting that right?
Ben
--
Ben Tupper
Bigelow Laboratory for Ocean Science
tupper@seadas.bigelow.org
pemaquidriver@tidewater.net
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