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Re: determining if a structure has a given tag [message #66918]

Wed, 17 June 2009 17:12

Jeremy Bailin
Messages: 618
Registered: April 2008

Senior Member

On Jun 17, 8:09 am, Reimar Bauer <R.Ba...@fz-juelich.de> wrote:
> Jeremy Bailin schrieb:
>
>
>
>> I'm sure there is a simple answer to this, but I can't find it.
>
>> Does someone know of a programmatic way to determine if a given tag is
>> defined in a structure, without resorting to TAG_NAMES (which seems
>> downright ugly). I can do something like
>
>> if n_elements(variable) eq 0
>
>> to determine if a variable has been defined, but to figure out if a
>> structure tag is defined I need to grab a list of all tags?? I guess I
>> want something that's functionally equivalent to:
>
>> if total(tag_names(struct) eq strupcase(tag)) gt 0
>
>> but which doesn't make me shudder. The closest discussion I can find
>> on this is here:
>> http://groups.google.com/group/comp.lang.idl-pvwave/browse_t hread/thr...
>> ...but most of that focuses on the peculiarities of dealing with
>> _EXTRA, not the more generic case.
>
>> -Jeremy.
>
> Result=is_tag(structure,tagname)
>
> http://www.fz-juelich.de/icg/icg-1/idl_icglib/idl_source/idl _html/dba...
>
> cheers
> Reimar

So the basic answer appears to be "no, you can't do it without using
TAG_NAMES, but you can encapsulate it inside another function so you
don't notice." ;-)

-Jeremy.

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[Message index]

		Re: determining if a structure has a given tag By: Jeremy Bailin on Wed, 17 June 2009 17:12
		Re: determining if a structure has a given tag By: R.Bauer on Wed, 17 June 2009 05:09
		Re: determining if a structure has a given tag By: mankoff on Wed, 17 June 2009 03:00
		Re: determining if a structure has a given tag By: dosfun on Tue, 16 June 2009 22:51

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