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Re: _overloadMinus: what to do with invalid input? [message #89929 is a reply to message #89928]

Mon, 29 December 2014 11:41

Michael Galloy
Messages: 1114
Registered: April 2006

Senior Member

Paul van Delst <paul.vandelst@noaa.gov> wrote:
> Hello,
>
> I am overloading the "-" operator for various objects and I have a
> philosophical question about what to do when the objects do not match.
>
> For example, should one return a FALSE result if the objects are not the same, e.g.
>
> FUNCTION Cloud::_overloadMinus, left, right
> IF ( (~ ISA(left,'Cloud')) || (~ ISA(right,'Cloud')) ) THEN $
> RETURN, FALSE
>
> giving:
>
>> q = fd_cloud[0] - 1
>> help, q
> Q INT = 0
>
>
> ...or should one throw an error an halt, e.g.
>
>
> FUNCTION Cloud::_overloadMinus, left, right
> IF ( (~ ISA(left,'Cloud')) || (~ ISA(right,'Cloud')) ) THEN $
> MESSAGE, 'Must supply two Cloud objects for subtraction'
>
> leading to:
>
>> q = fd_cloud[0] - 1
> % CLOUD::_OVERLOADMINUS: Must supply two Cloud objects for subtraction
>
>
> Which is the more idiomatic for IDL?
>
> cheers,
>
> paulv

I would think an error and halting, like IDL would do if you tried to use
an invalid operator with the native types. What happens if you try to add
two pointers? (not in front of my computer right now)

Mike
--
www.michaelgalloy.com
Research Mathematician
Tech-X Corporation

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[Message index]

		_overloadMinus: what to do with invalid input? By: Paul Van Delst[1] on Mon, 29 December 2014 10:34
		Re: _overloadMinus: what to do with invalid input? By: Michael Galloy on Mon, 29 December 2014 11:41
		Re: _overloadMinus: what to do with invalid input? By: penteado on Mon, 29 December 2014 14:27
		Re: _overloadMinus: what to do with invalid input? By: Paul Van Delst[1] on Tue, 30 December 2014 06:58

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