How do I include a C++ class in a namespace into Cython?

Question

I'm trying to create a wrap for a set C++ classes so I can use it in Python using Cython. This is what I have tried so far.

cdef extern from "HilClass.h" namespace "acro":
    cdef cppclass _HilClass "HilClass":
        void start()

cdef class HilClass:
    cdef _HilClass *ptr

    cpdef start(self):
        self.ptr.start()

That doesn't compile. I get the errors below, which by now I've come to learn that a possible cause is that it doesn't find the class. So after checking I had properly included the headers and sources I looked into the .cpp generated by Cython. I searched for acro but was unable to find it. It wasn't mentioned anywhere in the code.

error C2143: syntax error: missing ';' before '*'
error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
error C2238: unexpected token(s) preceding ';'
... (more warning and errors related to HilClass)

This is when I decided to change the second line to.

    cdef cppclass _HilClass "acro::HilClass":

This does compile. But this wasn't done in any example/tutorial I've found. So my question is, I'm I missing something and will my 'workaround' keep working reliably.

NOTE: I'm not interested in creating an instance of this class from within Python or Cython, I just need it to wrap around a HilClass pointer.

EDIT: This is the code inside 'HilClass.h'. 'acrophobe.h' has a few class forward declarations, enums, typedef unint#_t ####, and includes stdint.

#include "acrophobe.h"

namespace acro {
    class HilClass
    {
    public:
        HilClass(AcrophobeClass *acro_ptr);
        ~HilClass();

        HILSocketClass *sck;

        void start();
        void acrophile_iteration(char dest, lbp::PortID_t PortID);

        void set_activity_iteration_start(bool s);
        // More of these set_activity functions
        void set_activity_logging(bool s);


    private:
        AcrophobeClass *acro;

    };
}

Answer 1

You need to define as you have done

cdef cppclass _HilClass "acro::HilClass"

because you are giving acro::HilClass an alias _HilClass. You could test what happens if you define

cdef cppclass HilClass:
    void start()

and then later (the class name is just for an example)

cdef class PyHilClass:
    cdef HilClass * ptr

I don't see any reason why your solution would not be reliable.