| Re: Initializing object array [message #38425 is a reply to message #38420] |
Tue, 09 March 2004 01:53   |
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marc schellens[1]
Messages: 183
Registered: January 2000
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Senior Member |
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David Fanning wrote:
> 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]
IDL> a=indgen(5)
IDL> help,a
A INT = Array[5]
Its an *array* of object references, as 'a' is an *array* of INT.
> 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!?
Its all perfectly fine.
Maybe you used before a container?
Cheers,
marc
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