| Re: object creation question [message #11531] |
Thu, 23 April 1998 00:00  |
Evilio del Rio
Messages: 17
Registered: December 1997
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Junior Member |
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On Mon, 20 Apr 1998, Louis J. Wicker wrote:
> I am trying to use objects to help develop a 2D plotting package for my
> cloud model data. I have run into a conceptual snag, and think that I am
> missing something obvious. Suppose I want to create an object which
> stores, amoung other things, a 2d array of data (like for imaging or
> contouring, etc). So I create the object using:
>
> --
> data2d = obj_new('scalar2d')
> --
>
> Then I define a structure definition as:
>
> --
> Pro scalar2d__define
>
> struct = {scalar2d, sdata: fltarr(nx,ny)}
>
> End
> --
>
> and then an init method:
>
> --
> Pro scalar2d::init
>
> array = fltarr(20,30)
>
> self.sdata = array
>
> End
> --
Hi Louis,
You need to use pointers. That's the not so obvious bit you are missing.
Look the documentation for the procedures, PTR_NEW(), PTR_FREE,
PTR_VALID(), etc. Here's a bit of code that can do what you
want (more or less...):
FUNCTION scalar2d::init,DATA=data ; Init method must be a function.
if (N_Elements(data) GT 1) then begin
; Put stuff to chek if input data is correct...
endif else return,0
self.sdata = PTR_NEW(data)
return,1
End
Pro scalar2d::cleanup
PTR_FREE,self.sdata ; Clean up allocated memory.
end
Pro scalar2d::plot
plot, *self.sdata
end
Pro scalar2d__define
struct = {scalar2d, sdata: PTR_NEW()}
End
---
data2d = obj_new('scalar2d',DATA=myData)
---
Hth.
Cheers,
____________________________________________________________ ________
Evilio Jose del Rio Silvan Institut de Ciencies del Mar
E-mail: edelrio@icm.csic.es URL: http://www.ieec.fcr.es/~evilio/
"Anywhere you choose,/ Anyway, you're gonna lose"- Mike Oldfield
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