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Re: Finding if a structure tag name is defined? [message #36693 is a reply to message #36688]

Tue, 14 October 2003 19:35

Mark Hadfield
Messages: 783
Registered: May 1995

Senior Member

wmc@bas.ac.uk wrote:
> David Fanning <david@dfanning.com> wrote:
>
>> Reimar Bauer writes:
>>
>>> I often use is_tag to determine if a tag is in a structure
>
>> But, alas, you are still going to have to call IS_TAG
>> as many times as you have letters in your keyword, if
>> you hope to fish it out unambiguously. :-(
>
> Hmm, so, isn't that a flaw in IDL? Taking on board your
> well-reasonsed critique of (over)using _extra, it still seems
> quite reasonable to expect to be able to find if a given tag
> exists in a given structure, via a mechanism as simple as
> using n_elements to see if a given variable exist. IDL seems
> to make this simple task harder than it should be.
>
> (and anyway, looking at the pro, it only needs calling once).

I thought David's point was that searching for a tag in the _EXTRA
structure (which is a little harder than it should be in IDL, but not
all that onerous) is something you generally should not do, because it
becomes laborious if you want to support keyword abbreviation. And of
course you *do* want to handle keyword abbrevation, unless you want to
write documentation that says "IDL allows abbreviated keywords, except
in my routines".

If you aren't interested in a keyword in the current routine, bundle it
in an _EXTRA structure (or _REF_EXTRA hidden string-array thingy). If
you do, declare it explicitly.

--
Mark Hadfield "Ka puwaha te tai nei, Hoea tatou"
m.hadfield@niwa.co.nz
National Institute for Water and Atmospheric Research (NIWA)

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[Message index]

		Re: Finding if a structure tag name is defined? By: mvukovic on Wed, 15 October 2003 11:51
		Re: Finding if a structure tag name is defined? By: Mark Hadfield on Tue, 14 October 2003 19:35
		Re: Finding if a structure tag name is defined? By: David Fanning on Tue, 14 October 2003 15:19
		Re: Finding if a structure tag name is defined? By: wmconnolley on Tue, 14 October 2003 14:53
		Re: Finding if a structure tag name is defined? By: David Fanning on Tue, 14 October 2003 09:55
		Re: Finding if a structure tag name is defined? By: R.Bauer on Tue, 14 October 2003 09:34
		Re: Finding if a structure tag name is defined? By: David Fanning on Tue, 14 October 2003 07:32

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