yarp bindings give error with Vector conversion

[towardthesea]

Describe the bug
I used to do following in Python with yarp bindings to convert a Swig object of Vector to Vector in yarp 2.x, for example when using iKin to get the current joint angles of the iCubArm

        angle = self._iArm.getAng()  #_iArm = icub.iCubArm('right')
        print('angle', angle)
        angle_vector = yarp.Vector(angle)  # my result yarp Vector of joint angles

However, I got following error when doing the same with yarp 3.x

('angle', <Swig Object of type 'yarp::sig::Vector *' at 0x7f82a0098240>)
Traceback (most recent call last):
  File "demo/yarp_demo.py", line 550, in <module>
    arm_estimation.runModule(rf)
...
    return _yarp.RFModule_runModule(self, *args)
  File "demo/yarp_demo.py", line 264, in updateModule
    self.predict_yarp
  File "demo/yarp_demo.py", line 443, in predict_yarp
    angle_vector = yarp.Vector(angle)
  File "/home/pnguyen/icub-workspace/yarp/build/lib/python/yarp.py", line 13830, in __init__
    this = _yarp.new_Vector(*args)
NotImplementedError: Wrong number or type of arguments for overloaded function 'new_Vector'.
  Possible C/C++ prototypes are:
    yarp::sig::VectorOf< double >::VectorOf()
    yarp::sig::VectorOf< double >::VectorOf(size_t)
    yarp::sig::VectorOf< double >::VectorOf(size_t,double const &)
    yarp::sig::VectorOf< double >::VectorOf(size_t,double const *)
    yarp::sig::VectorOf< double >::VectorOf(yarp::sig::VectorOf< double > const &)

swig/python detected a memory leak of type 'yarp::sig::Vector *', no destructor found.

and the application failed.

Configuration (please complete the following information):

• OS: ubuntu 16.04
• yarp version: >3.1 (devel)
  
  
  
  • compiler:
  
  

Probably some changes with the definition of Vector in yarp 3.x causes some mismatches after conversion of swig.

[towardthesea]

cc @nunoguedelha @traversaro @Nicogene

[towardthesea]

Add another typedef in yarp.i file like this:

%inline %{
    typedef yarp::sig::VectorOf<double> Vector;
%}

before:

%template(Vector) yarp::sig::VectorOf<double>;

can help solve the issue.

Tested with python binding only!

[nunoguedelha]

Very nice solution! hoping it will work with Matlab bindings. Well it should. I'll test ASAP.

[towardthesea]

Also worked with Java through Matlab (I mean this )!

[nunoguedelha]

I just tested:

• the Matlab bindings using the Mex file directly still work fine
• I couldn't get rid of the fix that replaced all yarp::sig::Vector instances by yarp::sig::VectorOf (https://github.com/robotology/yarp/pull/1811)

Beware of this issue https://github.com/robotology/yarp/commit/2417c7d5e50aebca2ca8532fb40e7084262d50e8, which fix consisted in making SWIG skip the typedef of Vector: https://github.com/robotology/yarp/blob/2417c7d5e50aebca2ca8532fb40e7084262d50e8/src/libYARP_sig/include/yarp/sig/Vector.h#L35-L37

Without this guard, the Ruby bindings generation were crashing!

CC @Nicogene

[towardthesea]

I can compile with Lua and Ruby options but cannot test them. Maybe @vtikha can help with Lua test

[nunoguedelha]

Python bindings fixed by https://github.com/robotology/yarp/pull/1828. Also fixes some left overs on Matlab bindings regarding issue with yarp::sig::Vector.

[traversaro]

Should have been fixed by the merge of https://github.com/robotology/yarp/pull/1828 . Let us know if there are more problems.

[Nicogene]

I removed

inline %{
typedef yarp::sig::VectorOf<double> Vector;
%}

from yarp.i, keeping %template(Vector) yarp::sig::VectorOf<double>;
and the test proposed by @traversaro

import yarp
import unittest

class VectorTest(unittest.TestCase):

    def test_vector_copy_costructor(self):
        vecSize = 10
        vec = yarp.Vector(vecSize)
        self.assertEqual(vec.size(), vecSize)
        vecCheck = yarp.Vector(vec)
        self.assertEqual(vec.size(), vecCheck.size())


if __name__ == '__main__':
    unittest.main() 

works fine.
Maybe we are missing the point here, what is the type of angle?
Because looking around I see that the two directive for SWIG templates are quite the same

[traversaro]

Actually the test that I proposed was not effective in capturing the issue. I guess it is something related to functions that are returing a yarp::sig::Vector, but I could not find one to test in YARP that is wrapped in the bindings.

[nunoguedelha]

FYI there was a typo in https://github.com/robotology/yarp/pull/1828, so I've submitted a PR https://github.com/robotology/yarp/pull/1840 with what should be a cleaner fix, not using %inline at all but %{...%} along with the %template which was already there.

[towardthesea]

Actually the test that I proposed was not effective in capturing the issue. I guess it is something related to functions that are returing a yarp::sig::Vector, but I could not find one to test in YARP that is wrapped in the bindings.

@Nicogene Indeed, the errors with VectorOf only show when you call a function with Vector as argument.

[Nicogene]

Ah I see! The problem wasn't the copy constructor but this line:

print('angle',angle)

where angle is a yarp::sig::Vector.

[Nicogene]

The problem comes out when you try to construct a Vector from a Vector returned by a function, in #1840 I added test that check this issue.

[Nicogene]

Closing when #1840 will be merged

[Nicogene]

Fixed by #1840