Re: object oriented dilemma

[davidf(at)dfanning.com (David Fanning)]

Jason Li (jylimd@yahoo.com) writes:

> If I want to write an image processing software using OOP method, I would
> normally define a structure in __define module:
> 
> PRO myProgram__define
>     struct = {imagePointer:Ptr_New()}
> END
> 
> Traditionally, a pointer is used to take care of variable image size. Then
> load an image to self.imagePointer in the myProgram__init module.
> 
> hugeImage = bytarr(huge, huge)
> self.imagePointer = Ptr_New(hugeImage, /no_copy)
> 
> 
> Now in my METHOD modules, I have to perform an operation on line by line
> basis. I don't know how to get a line data out of this self.imagePointer
> without making a copy (dereferencing) of it first. My image size is rather
> large. I don't how to be more memory efficient.
> 
> Question: What is the solution to this?

I presume you mean you are taking a line of your image
like this:

   line = (*self.imagePointer)[5,*]

I find it hard to believe (given what I know about how
pointers work in IDL) that this takes any more memory
than this does:

   line = self.image[5,*]

What evidence do you have that a huge amount of memory
is being used?

Everything I know about pointer variables convinces me
that they are really treated like any other IDL variable
inside of IDL. Evidence to the contrary would be depressing. :-(

Cheers,

David
-- 
David Fanning, Ph.D.
Fanning Software Consulting
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