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Re: indexing a structure in a list [message #87475 is a reply to message #87474]

Wed, 05 February 2014 10:05

Michael Galloy
Messages: 1114
Registered: April 2006

Senior Member

On 2/5/14, 10:52 AM, Craig Markwardt wrote:
> On Wednesday, February 5, 2014 11:36:09 AM UTC-5, Helder wrote:
>> Hi,
>>
>> I've got the feeling this should work, but for some reason it isn't.
>>
>> So here is some code to test the problem with the errors describe in it:
>>
>>
>>
>> PRO testStrutRef
>> Compile_Opt idl2
>> a = list(findgen(10), /extract)
>> a[4] = {value:3.0}
>> help, a[4], /struct
>> ;a[4].value = 4.0 ;won't work: % Attempt to store into an expression: >
>> ;(a[4]).value = 4.0 ;won't work: % Attempt to store into an expression: Structure reference.
>> ;((a)[4]).value = 4.0 ;won't work: % Attempt to store into an expression: Structure reference.
>> struct = a[4]
>> struct.value = 4.0
>> a[4] = struct ;works, but not really straight forward...
>> print, a
>> END
>>
>> It seems like I can't address a structure element of a list directly.
>> Did I misplace my parenthesis? Is there a less cumbersome workaround?
>
> Seems like a flat-out bug to me. List elements should be "lvalues," as they say in the compile business.
> Craig
>

Yes, seems like a bug. Note that index notation works:

IDL> print, (a[4]).(0)
3.00000

Mike
--
Michael Galloy
www.michaelgalloy.com
Modern IDL: A Guide to IDL Programming (http://modernidl.idldev.com)
Research Mathematician
Tech-X Corporation

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[Message index]

		indexing a structure in a list By: Helder Marchetto on Wed, 05 February 2014 08:36
		Re: indexing a structure in a list By: David Fanning on Wed, 05 February 2014 09:00
		Re: indexing a structure in a list By: Craig Markwardt on Wed, 05 February 2014 09:52
		Re: indexing a structure in a list By: Michael Galloy on Wed, 05 February 2014 10:05
		Re: indexing a structure in a list By: Helder Marchetto on Wed, 05 February 2014 11:42

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