| Re: Initializing object array [message #38426 is a reply to message #38425] |
Mon, 08 March 2004 22:31   |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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Dick Jackson writes:
> class = { MYCLASS, contours:ObjArr(nElements)}
>
> would do it, but it will be a fixed number of elements, and the passed
> 'contours' would have to match that. If that's what you need, then fine,
> but I bet you need flexibility. All I can see for a solution right now
> is using a pointer:
>
> class = { MYCLASS, contours:Ptr_New(/Allocate_Heap)}
>
> then, to assign it:
> *self.contours = contours
>
> and to refer to one contour:
> (*self.contours)[i]
>
> Sorry if I'm stating the obvious... or am *I* missing something?
Well, after taking a nap I can see that it is going to
have to be a pointer, but I still can't see why. :-)
I often use object containers to store objects, but I guess
this might have been the first time (at least in a while)
that I tried to store an object array. Oddly, an object
array is an object reference:
IDL> a = ObjArr(5)
IDL> Help, a
A OBJREF = Array[5]
So you might think that if b was initialized as an object reference,
you could store an object array in it. It should fit, it's just a
long integer.
IDL> struct = {b:Obj_New()}
IDL> struct.b = a
% Expression must be a scalar in this context: A.
Of course, with a structure I can do this:
IDL> struct = {c:ObjArr(5)}
IDL> struct.c = a
But I can't see a way to initialize an *object* like that. For example,
this doesn't work:
FUNCTION MyProg::INIT, a
self.c = ObjArr(5)
self.c = a
RETURN, 1
END
PRO MyProg__Define
class = {MYPROG, c:Obj_New()}
END
When I run it, I get this:
IDL> d = Obj_New('myprog', a)
% Expression must be a scalar in this context: <OBJREF Array[5]>.
Isn't that strange!?
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting
Coyote's Guide to IDL Programming: http://www.dfanning.com/
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