[Octave-bug-tracker] [bug #60237] Differente behaviour in anonymous function handling

[Denis Sbragion]

Follow-up Comment #5, bug #60237 (project octave):

Hello,

I think I nailed down the problem. I started from the textbook example at:

https://octave.org/doc/v6.2.0/Calling-Octave-Functions-from-Oct_002dFiles.html#Calling-Octave-Functions-from-Oct_002dFiles

and compared it to the NLOpt Octave interface. In the end it all boils down to
the following situation:


#include <octave/oct.h>
#include <octave/parse.h>

DEFMETHOD_DLD (callback, interp, args, nargout, "Callback Demo")
{
        int nargin = args.length ();

        if (nargin < 2)
                print_usage ();

        octave_value_list newargs;

        for (octave_idx_type i = nargin - 1; i > 0; i--)
                newargs(i-1) = args(i);

        octave_value_list retval;

        // Works
        retval = interp.feval (args(0), newargs, nargout);

        // Fails
        retval = interp.feval (args(0).function_value(), newargs, nargout);

        return retval;
}


This trivial callback function has to be called passing an anonymous function
with context inherited parameters like in the antest() example to see the
problem happening.

The NLOpt interface uses some more convoluted code which is equivalent to the
failing one above. I don't know if there has been some API change which
forbids the second type of call in 6.X. If this is the case I'll fix the NLOpt
interface and warn back the NLOpt developers.

Let me know.

Bye,

Denis Sbragion

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