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Re: How to delete a variable [message #88383 is a reply to message #88382]

Fri, 18 April 2014 13:24

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

wlandsman writes:

> There are times when one wants to delete variables inside a program to save memory. (The intrinsic DELVAR command can only be called at the main level.) For example, the Coyote program UNDEFINE ( http://www.idlcoyote.com/programs/undefine.pro ) tests whether a variable is a pointer, object, structure or ordinary variable, and will apply HEAP_FREE, OBJ_DESTROY, iteration, or set an ordinary variable to 0.
>
> I was using a more elegant but apparently less reliable solution in delvarx.pro
> http://idlastro.gsfc.nasa.gov/ftp/pro/misc/delvarx.pro
>
> in which the single statement
>
> Heap_Free, PTR_NEW(x , /No_Copy)
>
> would release the memory and destroy any type of IDL variable x. But I have gotten reports that in some cases this can be terribly slow. Actually the two reports have both been on CentOS Linux systems running IDL 7.0, so perhaps this is a problem fixed in more recent versions of IDL. But can anyone think of a reason why the above statement is not good way to release memory?

Well, HEAP_FREE has to search the entire variable list for heap
variables no longer attached to a reference. Perhaps you mean Ptr_Free.

Cheers,

David

--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.idlcoyote.com/
Sepore ma de ni thue. ("Perhaps thou speakest truth.")

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[Message index]

		How to delete a variable By: wlandsman on Fri, 18 April 2014 12:29
		Re: How to delete a variable By: David Fanning on Fri, 18 April 2014 13:24
		Re: How to delete a variable By: wlandsman on Fri, 18 April 2014 13:31
		Re: How to delete a variable By: jigga1206 on Fri, 18 April 2014 13:29
		Re: How to delete a variable By: Fabzi on Wed, 23 April 2014 07:30
		Re: How to delete a variable By: David Fanning on Wed, 23 April 2014 07:34
		Re: How to delete a variable By: Craig Markwardt on Wed, 23 April 2014 08:09
		Re: How to delete a variable By: David Fanning on Wed, 23 April 2014 08:38
		Re: How to delete a variable By: wlandsman on Wed, 23 April 2014 10:42

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