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Re: Tough System Variable Question for the IDL Gurus [message #68621]

Wed, 11 November 2009 17:51

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

David Fanning writes:

> Maybe a pointer *will* work.
>
> IDL> defsysv, '!tester', Ptr_New(5)
> IDL> help, !tester
> <Expression> POINTER = <PtrHeapVar795>
> IDL> help, *!tester
> <PtrHeapVar795> LONG = 5
> IDL> ptr_Free, !tester
> IDL> !tester = Ptr_New(/ALLOCATE_HEAP)
> IDL> help, /heap
> Heap Variables:
> # Pointer: 1
> # Object : 0
>
> <PtrHeapVar2> UNDEFINED = <Undefined>

Well, this could be confusing. Let me take my example
all from the same IDL session:

IDL> defsysv, '!tester', Ptr_New(5)
IDL> help, !tester
<Expression> POINTER = <PtrHeapVar1>
IDL> help, *!tester
<PtrHeapVar1> LONG = 5
IDL> Ptr_Free, !tester
IDL> !tester = Ptr_New(/Allocate_Heap)
IDL> help, !tester
<Expression> POINTER = <PtrHeapVar2>
IDL> help, *!tester
<PtrHeapVar2> UNDEFINED = <Undefined>
IDL> help, /heap
Heap Variables:
# Pointer: 1
# Object : 0
<PtrHeapVar2> UNDEFINED = <Undefined>
IDL> Ptr_Free, !tester
IDL> help, /heap
Heap Variables:
# Pointer: 0
# Object : 0

Cheers,

David

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

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[Message index]

		Re: Tough System Variable Question for the IDL Gurus By: David Fanning on Wed, 11 November 2009 17:51
		Re: Tough System Variable Question for the IDL Gurus By: David Fanning on Wed, 11 November 2009 17:45
		Re: Tough System Variable Question for the IDL Gurus By: ben.bighair on Wed, 11 November 2009 16:12
		Re: Tough System Variable Question for the IDL Gurus By: Foldy Lajos on Wed, 11 November 2009 14:26

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