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Re: Empty FOREACH loop [message #81734 is a reply to message #75101]

Fri, 12 October 2012 14:33

Dick Jackson
Messages: 347
Registered: August 1998

Senior Member

> On 2/14/11 8:08 pm, Paulo Penteado wrote:
>>
>> I also get the temporary variables stuff, and agree that things like
>>
>> foreach el,!null do print,el
>> foreach el,[] do print,el
>> foreach el,{} do print,el
>>
>> Should all do nothing, with no errors.
>>
>> But if foreach is given a named variable that is !null it does nothing
>> as expected:
>>
>> IDL> n=!null
>> IDL> foreach el,n do print,el

Those examples are good, but today I realize I'd really like this to work (quietly do no iterations) if I use an undefined variable (such as an unfilled keyword variable):

IDL> foreach x, myUndefinedNonVariable do print,x
% Variable is undefined: MYUNDEFINEDNONVARIABLE.
% Execution halted at: $MAIN$

Would anyone else agree that with no elements in myUndefinedNonVariable, this should quietly do no iterations?

Cheers,
-Dick

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[Message index]

		Re: Empty FOREACH loop By: Michael Galloy on Tue, 15 February 2011 06:14
		Re: Empty FOREACH loop By: penteado on Mon, 14 February 2011 19:08
		Re: Empty FOREACH loop By: Dick Jackson on Fri, 12 October 2012 14:33

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