Re: scope of variable in NCL

Hi,

For what it is worth, I am puzzled by how the original example even
worked.

  Copyright (C) 1995-2009 - All Rights Reserved
  University Corporation for Atmospheric Research
  NCAR Command Language Version 5.1.1
  The use of this software is governed by a License Agreement.
  See http://www.ncl.ucar.edu/ for more details.
ncl 0> function test(a,b,c)
ncl 1> local a,b,c
ncl 2> begin
ncl 3> a=-999
ncl 4> return(1)
ncl 5> end
ncl 6> print(""+test(a,1,2))
fatal:Variable (a) is undefined
fatal:Execute: Error occurred at or near line 6

daryl

On Fri, 16 Oct 2009, David Brown wrote:

> Hi Saji,
> Wei is quite correct about this case. Arguments are passed by
> reference and the variables they reference can be modified inside the
> function. The 'local' statement has no meaning for arguments. You can
> ignore the last message I sent. I apologize that I did not notice that
> 'a' was being used as an argument to the function.
> -dave
>
> On Oct 16, 2009, at 8:09 AM, Wei Huang wrote:
>
>> Saji,
>>
>> That is because you use "a" as an argument element, and local.
>>
>> If you do "print("" + test(0,1,2))", then you can not change "a"
>> out side your function.
>>
>> Wei Huang
>> huangwei@ucar.edu
>> VETS/CISL
>> National Center for Atmospheric Research
>> P.O. Box 3000 (1850 Table Mesa Dr.)
>> Boulder, CO 80307-3000 USA
>> (303) 497-8924
>>
>>
>>
>>
>>
>> On Oct 15, 2009, at 11:03 PM, Saji N Hameed wrote:
>>
>>> Even declaring "a" as local does not seem to work :(
>>> ncl 1> function test(a,b,c)
>>> ncl 2> local a,b,c
>>> ncl 3> begin
>>> ncl 4> a=-999
>>> ncl 5> return(1)
>>> ncl 6> end
>>> ncl 7> print(""+test(a,1,2))
>>> (0) 1
>>> ncl 8> print(""+a)
>>> (0) -999
>>>
>>> * Saji N Hameed <saji@apcc21.net> [2009-10-16 13:59:15 +0900]:
>>>
>>>> Dear NCL Developers,
>>>>
>>>> I suppose that the following should not happen. Isn't it a bug?
>>>> We are told that variables inside a function have local scope, and
>>>> this unusual feature can lead to a lot of headaches. Any solutions,
>>>> other than "local a" or using another variable name than "a"
>>>>
>>>> Copyright (C) 1995-2009 - All Rights Reserved
>>>> University Corporation for Atmospheric Research
>>>> NCAR Command Language Version 5.1.1
>>>> The use of this software is governed by a License Agreement.
>>>> See http://www.ncl.ucar.edu/ for more details.
>>>> ncl 0> a=5
>>>> ncl 1> function testme(a,b,c)
>>>> ncl 2> begin
>>>> ncl 3> a=2
>>>> ncl 4> return(1)
>>>> ncl 5> end
>>>> ncl 6> print(""+a)
>>>> (0) 5
>>>> ncl 7> print(""+testme(a,1,2))
>>>> (0) 1
>>>> ncl 8> print(""+a)
>>>> (0) 2
>>>>
>>>> Thanks,
>>>> saji
>>>> --
>>>>
>>>>
>>>> _______________________________________________
>>>> ncl-talk mailing list
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>>>>
>>>
>>> --
>>> Saji N. Hameed
>>>
>>> APEC Climate Center
>>> 1463 U-dong, Haeundae-gu, +82 51 745
>>> 3951
>>> BUSAN 612-020, KOREA saji@apcc21.net
>>> Fax: +82-51-745-3999
>>>
>>>
>>>
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>>
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Received on Fri Oct 16 09:34:56 2009