call Cython function from C++

Question

I have a C++ library that has a Python wrapper (written with SWIG). This library allows executing small user-defined code (a callback), such as element-wise operations on a

Answer 1

You can achieve that by doing pure cdef functions :

# declare the prototype of your function
ctypedef void (*callback_ptr)(int arg)

# declare your function as cdef
cdef void my_callback(int arg):
    print 'doing some python here', arg

# now, you can use the cdef func as a callback
# in pure C !
cdef void run():
    cdef callback_ptr p = my_callback
    p(42)

if __name__ == '__main__':
    run()

Note: you can use "cython -a" to see that they are no python code involved for the content of run. So it will work with your c library.