Re: `argn' ? … still part of Octave ?

[Ben Abbott]

On Oct 5, 2011, at 9:31 PM, Carnë Draug wrote:

> On 6 October 2011 01:42, Ben Abbott <address@hidden> wrote:
>> On Oct 5, 2011, at 8:11 PM, Carnë Draug wrote:
>>> On 5 October 2011 13:28, Ben Abbott <address@hidden> wrote:
>>>> On Oct 5, 2011, at 12:07 AM, John W. Eaton wrote:
>>>>> On  4-Oct-2011, Ben Abbott wrote:
>>>>> | I noticed in the doc string for "whos" that "argn" is mentioned ...
>>>>> |
>>>>> | "Automatic variable.  An automatic variable is one created by the 
>>>>> interpreter, for example `argn'."
>>>>> |
>>>>> | Is "argn" still a part of Octave, and if so, what is its function?
>>>>> 
>>>>> It's like inputname, but it can return something even if the argument
>>>>> was an expression.
>>>> 
>>>> Thanks. I asked because of the bug reported below.
>>>> 
>>>>        https://savannah.gnu.org/bugs/?34478
>>>> 
>>>> Apparently, "argn" isn't working for the private functions for @-style 
>>>> objects.
>>> 
>>> Hi
>>> 
>>> I found this because I wanted to implement a new class and was trying
>>> to mimic the obj.method type of API (for matlab compatibility). The
>>> idea is to use arg (or inputname) to get the name of the variable in
>>> the caller and change its value with assignin('caller',...)
>>> 
>>> 
>>>> Playing a bit, I noticed some unexpected behavior (I was curious how argn 
>>>> compared with inputname())
>>> 
>>> By the way, since inputname just evals args in the caller, it has the same 
>>> bug.
>>> 
>>>> function varargout = fubar (varargin)
>>>>  varargout{1} = argn(1:nargin);
>>>>  for n = 1:nargin
>>>>    varargout{2}(n) = {inputname(n)};
>>>>  endfor
>>>> endfunction
>>>> 
>>>> a = 1; b = 2; c = 3; d = 4;
>>>> 
>>>> [args, inputs] = fubar(a, b, c, d)
>>>> args =
>>>> 
>>>> a
>>>> b
>>>> c
>>>> d
>>>> 
>>>> inputs =
>>>> {
>>>>  [1,1] = a
>>>>  [1,2] = b
>>>>  [1,3] = c
>>>>  [1,4] = d
>>>> }
>>>> 
>>>> [args, inputs] = fubar(a, b, a*b, c, d)
>>>> args = abacd
>>>> inputs =
>>>> {
>>>>  [1,1] = a
>>>>  [1,2] = b
>>>>  [1,3] =
>>>>  [1,4] = c
>>>>  [1,5] = d
>>>> }
>>> 
>>> I don't think so. In the second example, inputname behaves correctly
>>> because arguments that don't have an identifier, should return an empty
>>> string. The third argument does not have a corresponding variable on
>>> the caller workspace (a*b) so inputname returns an empty string for
>>> those cases.
>>> 
>> 
>> Ok, you're right, inputname() is obviously working correctly. But the "args" 
>> in the second example is incorrect?
> 
> I checked again and it's not incorrect. The problem was in the loop to
> get argn in the cell array. The following works fine:
> 
> function fubar (varargin)
>    disp(argn)
> endfunction
> 
> a = 1; b = 2; c = 3; d = 4;
> 
> fubar (a, b, a*b, c, d)

Ok, so it appears when "a*b" is present a "\n" is missing?

Ben