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_overloadMinus: what to do with invalid input? [message #89928]

Mon, 29 December 2014 10:34

Paul Van Delst[1]
Messages: 1157
Registered: April 2002

Senior Member

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:

IDL> q = fd_cloud[0] - 1
IDL> 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:

IDL> q = fd_cloud[0] - 1
% CLOUD::_OVERLOADMINUS: Must supply two Cloud objects for subtraction

Which is the more idiomatic for IDL?

cheers,

paulv

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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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