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Re: Pass by value and performance [message #46700 is a reply to message #46698]

Wed, 14 December 2005 09:54

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

Kenneth P. Bowman writes:

> Perhaps someone can clarify this for me.
>
> I was doing this
>
> data = {values : FLTARR(...), $
> other : other stuff ...}
>
> Then pass "data" to a procedure and do this
>
> result = INTERPOLATE(data.values, x, y, z)
>
> In this case data.values is passed by reference. (p. 92 of Building IDL
> Applications)
>
>
> If I were to use pointers, I could do something like this instead
>
> data = {values : PTR_NEW(FLTARR(...)), $
> other : other stuff ...}
>
> Pass "data" to a procedure and do this
>
> result = INTERPOLATE(*data.values, x, y, z)
>
> Is *data.values passed by reference or by value? And how does one tell?

I would test it with my little JUNK program from before,
like so:

IDL> b = {ptr:Ptr_New(5)}
IDL> junk, *b.ptr
IDL> help, *b.ptr
<PtrHeapVar26> INT = 25

Whoa! Excuse me. I need to do a little more work on that
pointer chapter.

Cheers,

David

--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/

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[Message index]

		Re: Pass by value and performance By: JD Smith on Wed, 14 December 2005 11:04
		Re: Pass by value and performance By: David Fanning on Wed, 14 December 2005 09:54
		Re: Pass by value and performance By: Kenneth P. Bowman on Wed, 14 December 2005 09:28
		Re: Pass by value and performance By: David Fanning on Wed, 14 December 2005 09:08
		Re: Pass by value and performance By: Paul Van Delst[1] on Wed, 14 December 2005 09:02
		Re: Pass by value and performance By: David Fanning on Wed, 14 December 2005 07:53
		Re: Pass by value and performance By: Kenneth P. Bowman on Wed, 14 December 2005 07:09
		Re: Pass by value and performance By: peter.albert@gmx.de on Tue, 13 December 2005 23:38
		Re: Pass by value and performance By: Antonio Santiago on Wed, 14 December 2005 22:56

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