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Re: no backwards compatibility in IDL 5.6 [message #34276 is a reply to message #34266]

Mon, 03 March 2003 09:12

JD Smith
Messages: 850
Registered: December 1999

Senior Member

On Fri, 28 Feb 2003 13:02:15 -0700, JD Smith wrote:

> On Fri, 28 Feb 2003 12:42:42 -0700, David Fanning wrote:
>
>> Pavel Romashkin (pavel_romashkin@hotmail.com) writes:
>>
>>> Why is EXECUTE used in this program? Why can't the value just be
>>> returned from each CASE? Execute will slow it down and as far as I can
>>> tell, does nothing special. There is no code that follows the CASE to
>>> prevent you from returning at any point. Will it not compile in 5.4
>>> with the extra keyword? I thought keyword mismatches are runtime
>>> errors. Am I missing something?
>>
>> Alright, here is why I am using EXECUTE. If I change the code to this:
>>
>> returnValue = 0.0
>> version = Float(!VERSION.Release)
>> IF (version LE 5.5) THEN returnValue = ATAN(imgpart, realpart) $
>> ELSE returnValue = ATAN(complexNum, /Phase)
>>
>> Then the code won't compile in IDL 5.4, complaining about the PHASE
>> keyword not being defined. :-(
>>
>>
>> P.S. The code *does* compile in IDL 5.5, by the way, even though the
>> PHASE keyword is not defined there, either.
>
> Which is when _STRICT_EXTRA was first introduced. Coincidence?
>
> My consipiracy theory: RSI switched from checking built-in system
> routine keywords at compile to run-time with v5.5. This isn't the
> first time they've done this type of thing: around v5.3, they switched
> from checking the validity of system variables at compile time to run
> time (which was rather convenient, actually).
>
> JD

Just to clarify, for the sake of RSI's hard working engineers: this
conspiracy theory, like many others, is entertaining, but entirely
untrue. IDL checks at compile time whether *any* keywords are allowed
at all. Since ATAN went from having none to having one keyword, this
explains the difference.

JD

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[Message index]

		no backwards compatibility in IDL 5.6 By: Alexander Rauscher on Thu, 27 February 2003 04:52
		Re: no backwards compatibility in IDL 5.6 By: JD Smith on Mon, 03 March 2003 09:12
		Re: no backwards compatibility in IDL 5.6 By: David Fanning on Fri, 28 February 2003 20:40
		Re: no backwards compatibility in IDL 5.6 By: Craig Markwardt on Fri, 28 February 2003 18:20
		Re: no backwards compatibility in IDL 5.6 By: David Fanning on Fri, 28 February 2003 15:55
		Re: no backwards compatibility in IDL 5.6 By: Pavel Romashkin on Fri, 28 February 2003 15:32
		Re: no backwards compatibility in IDL 5.6 By: JD Smith on Fri, 28 February 2003 12:35
		Re: no backwards compatibility in IDL 5.6 By: David Fanning on Fri, 28 February 2003 12:28
		Re: no backwards compatibility in IDL 5.6 By: JD Smith on Fri, 28 February 2003 12:02

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