| Re: object argument passing behaviour changed in v8.2.2? [message #86275 is a reply to message #86274] |
Tue, 22 October 2013 10:17  |
chris_torrence@NOSPAM
Messages: 528
Registered: March 2007
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Senior Member |
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On Tuesday, October 22, 2013 10:59:18 AM UTC-6, Paul van Delst wrote:
> On 10/22/2013 11:57 AM, Chris Torrence wrote:
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>>
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>> Hi Paul,
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>> I don't think this is a special case. It's also not
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>> "semi-passed-by-reference." The code is simply passing an expression
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>> into a routine, so IDL cannot store into it.
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>> Cheers, Chris
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>
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> Well, that's not the case. Both your, and my corrected, test cases shows
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> that you *can* store into the array element reference (well, the object
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> that was referenced in that array element) in the callee.
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>
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> It was the "redefinition" of the object in the routine (or method) that
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> was screwing things up.
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>
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> I know it won't (can't) change anytime soon, but I find the fact that an
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> array element reference is considered an expression in IDL very
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> confusing. It just doesn't grok well.
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> IDL users should be shielded from under-the-hood details like argument
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> passing mechanisms, IMO (that's my Fortran90/95/2003 side talking).
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>
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> cheers,
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>
>
> paulv
Yep, I agree that a different decision would have been better. Unfortunately, we would have to travel back 30 years in time to tell David Stern... If I recall, Fortran 77 passed by reference (even for array elements), so David could have gotten it right... Oh well.
-Chris
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