| Re: Empty FOREACH loop [message #75101] |
Tue, 15 February 2011 06:14  |
Michael Galloy
Messages: 1114
Registered: April 2006
|
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
Even more interesting:
IDL> print, !version
{ x86_64 darwin unix Mac OS X 8.0.1 Oct 5 2010 64 64}
IDL> groups = !null
IDL> foreach g, groups do help, g
But:
IDL> print, !version
{ x86_64 linux unix linux 8.0 Jun 18 2010 64 64}
IDL> groups = !null
IDL> foreach g, groups do help, g
% Variable is undefined: GROUPS.
% Execution halted at: $MAIN$
This must be a fix in 8.0.1. I will do some more research, but sheds
some light on the original situation that was causing me some problems
debugging.
Mike
--
www.michaelgalloy.com
Research Mathematician
Tech-X Corporation
|
|
|
|
| Re: Empty FOREACH loop [message #75107 is a reply to message #75101] |
Mon, 14 February 2011 19:08  |
penteado
Messages: 866
Registered: February 2018
|
Senior Member
Administrator |
|
|
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
IDL>
On Feb 14, 9:47 pm, Michael Galloy <mgal...@gmail.com> wrote:
> I was quite surprised when the following raised an error for me:
>
> IDL> foreach g, [] do help, g
> % Variable is undefined: <UNDEFINED>.
> % Execution halted at: $MAIN$
>
> Does this seem like unexpected behavior? I was expecting the loop just
> not to execute.
>
> Of course, whatever the right answer is, it shouldn't do this (as it
> does on my Mac):
>
> IDL> foreach g, [] do help, g
> % Temporary variables are still checked out - cleaning up...
>
> Mike
> --www.michaelgalloy.com
> Research Mathematician
> Tech-X Corporation
|
|
|
|
| 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
|
|
|
|
comp.lang.idl-pvwave archive
Members
Search
Help
Login
Home
