Re: Accessing ComplexMatrix values from octave_value_list

[siko1056]

remigio wrote
> Hello Andy,
> 
> I tryed your suggestion and it didn't work, I made a minimum working
> example
> to help understand the problem : 
> ///////////////////////////////////////////////////////////////////////////////////
> #include <octave/oct.h>
> #include <octave/octave.h>
> #include 
> <cmath>
> DEFUN_DLD (function1, args, nargout,"function1")
> {
> ComplexMatrix  psi_int(2, 3);
> octave_value_list retval;
> retval(0) = octave_value(psi_int);
> return octave_value (retval);
> }
> 
> ///////////////////////////////////////////////////////////////////////////////////
> 
> #include &lt;octave/oct.h&gt;
> #include &lt;octave/octave.h&gt;
> #include &lt;octave/parse.h&gt;
> #include 
> <cmath>
> DEFUN_DLD (function2, args, nargout, "function2")
> {
> 
> octave_value_list out = feval("function1");
> ComplexMatrix psi_int = out(0).complex_matrix_value();
> 
> octave_value_list retval;
> retval(0) = octave_value(psi_int);
> return octave_value (retval);
> }
> 
> function1 executed in octave works fine and return a 2x3 zero matrix as
> expected but function2 which calls function1 and should return the same
> show
> the error message:
> 
> error: octave_base_value::complex_matrix_value(): wrong type argument
> 'cs-list'
> 
> I would be gratefull to anyone who can make clear what is wrong with this
> code,
> 
> Rémi

As Andy says, in function1, `return retval;` is fully sufficient, as
`retval` has already the correct type `octave_value_list`, you do not need
to wrap it again, see why:

What you do is the following (assume that `cs-list` and `octave_value_list`
are the same, which is not 100% true):

    octave_value_list retval;  // Create an empty `octave_value_list ()`
    retval(0) = octave_value(psi_int);  // Now we have `octave_value_list
(octave_value (ComplexMatrix))`
    return octave_value (retval);  // Now we return `octave_value
(octave_value_list (octave_value (ComplexMatrix)))`

This in turn will be wrapped again, because of the definition of DEFUN_DLD:

    octave_value_list (octave_value (octave_value_list (octave_value
(ComplexMatrix))))

Thus now when you unpack this from variable `out` in `function2` is:

    octave_value_list out = feval("function1");
    ComplexMatrix psi_int = out(0).complex_matrix_value();

where

    out(0)  // octave_value (octave_value_list (octave_value
(ComplexMatrix)))

is clearly to me an `octave_value_list`, not an `ComplexMatrix` in the 
first level.

HTH,
Kai




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