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IDL and pointers [message #18434] Wed, 12 January 2000 00:00 Go to next message
Jonathan Joseph is currently offline  Jonathan Joseph
Messages: 69
Registered: September 1998
Member
As far as I can tell, the analog to pointers in IDL is handles.
This is very inconvenient for dereferencing pointers to
structures - especially if you want to do multiple dereferencing.
This is because you need to call HANDLE_VALUE
(twice [using NO_COPY] if you don't want to waste time
making a copy of the data structure).

So, I thought that now that they have been here for a while,
IDL objects should be very useful in these cases - since
they have the dereference operator ".".

But, there does not seem to be a way to access the instance
data outside of an object method. I don't want to have
to write object methods for every little piece of my object I want
to access. In C++ I can define parts of the class to be public and I
can access them at will. Is there any analog to this in IDL?

The current setup seems very inconvenient - especially for
debugging. If I have an object "a" and I want to see what
is in it's "foo" field, I can't even do "IDL> print, a.foo" I get:

% Object instance data is not visible outside class methods: A

Am I missing something fundamental here? I just want
the equivalent of some nice dynamically allocated structures
that I can have multiple pointers to and easily dereference.

For example,

structure A has a field that is a pointer to structure B
structure B has a field that is a pointer to structure C
structure C has the field FOO

I want the equivalent of something like the following C++
assignment: F = A.B->C->FOO
or if we just had a pointer to A: F = A->B->C->FOO

Thanks for any insight.

-Jonathan
Re: IDL and pointers [message #18624 is a reply to message #18434] Sun, 16 January 2000 00:00 Go to previous message
marc schellens[1] is currently offline  marc schellens[1]
Messages: 183
Registered: January 2000
Senior Member
Jonathan Joseph wrote:
>
> Well,
>
> OK, (hangs head sheepishly) I did finally find the section in the
> online reference manuals about pointers and pointer dereferencing.
>
> But, I would still like to know about the possiblity of publicly
> accessible parts of objects.
>
> -Jonathan

Robert Mallozzi has written an generic get method for objects.
Check out:
http://gammaray.msfc.nasa.gov/~mallozzi/home/software/idl/sr c/generic__get.pro

cheers,
:-) marc
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