How to create a public cython function that can receive c++ struct/instance or python object as parameter? -

my rectangle.h

namespace shapes {     class rectangle {     public:         int x0, y0, x1, y1;         rectangle();         rectangle(int x0, int y0, int x1, int y1);         ~rectangle();         int getarea();     }; } 

my rectangle.cpp

#include "rectangle.h" namespace shapes {   rectangle::rectangle() { }     rectangle::rectangle(int x0, int y0, int x1, int y1) {         x0 = x0;         y0 = y0;         x1 = x1;         y1 = y1;     }     rectangle::~rectangle() { }     int rectangle::getarea() {         return (x1 - x0) * (y1 - y0);     } } 

my rect.pyx

# distutils: language = c++ # distutils: sources = rectangle.cpp  cdef extern "rectangle.h" namespace "shapes":     cdef cppclass rectangle:         rectangle() except +         rectangle(int, int, int, int) except +         int x0, y0, x1, y1         int getarea()  cdef class pyrectangle:     cdef rectangle c_rect     def __cinit__(self, int x0, int y0, int x1, int y1):         self.c_rect = rectangle(x0, y0, x1, y1)     def get_area(self):         return self.c_rect.getarea()  cdef public int cythonfunc(pyrectangle py_rect):     result = py_rect.get_area()     return result 

my main.cpp

#include <python.h>  #include "rect.h"  #include "rectangle.h" #include <iostream>  int main (int argc, char *argv[]) {   int result;   py_initialize();    pyinit_rect();   shapes::rectangle c_rect = shapes::rectangle(0,0,2,1);   result = cythonfunc(c_rect);   std::cout<<result<<"\n";    py_finalize();    return 0; } 

my makefile

all:         cython3 --cplus rect.pyx         c++ -g -o2 -c rect.cpp -o rect.o `python3-config --includes`         c++ -g -o2 -c rectangle.cpp -o rectangle.o `python3-config --includes`         c++ -g -o2 -c main.cpp -o main.o `python3-config --includes`         c++ -g -o2 -o rect rectangle.o rect.o main.o `python3-config --libs`  clean:         rm -f rect rect.cpp rect.h *.o 

my problem related "cythonfunc" in rect.pyx. intended public function can called main rectangle struct/object parameter, , return area main.cpp.

i've tried c struct , python object, both not work me. if use codes, compiler gives error of

error compiling cython file: ------------------------------------------------------------ ...     def __cinit__(self, int x0, int y0, int x1, int y1):         self.c_rect = rectangle(x0, y0, x1, y1)     def get_area(self):         return self.c_rect.getarea()  cdef public int cythonfunc(pyrectangle py_rect):                           ^ ------------------------------------------------------------  rect.pyx:19:27: function declared public or api may not have private types 

so added "public" pyrectangle, got error:

error compiling cython file: ------------------------------------------------------------ ...         rectangle() except +         rectangle(int, int, int, int) except +         int x0, y0, x1, y1         int getarea()  cdef public class pyrectangle:     ^ ------------------------------------------------------------  rect.pyx:12:5: type object name specification required 'public' c class 

if change cythonfunc to:

cdef public int cythonfunc(rectangle c_rect):     result = c_rect.getarea()     return result 

i got error of:

in file included main.cpp:3:0: rect.h:21:42: warning: ‘cythonfunc’ initialized , declared ‘extern’  __pyx_extern_c dl_import(int) cythonfunc(shapes::rectangle);                                           ^ rect.h:21:42: error: ‘shapes’ has not been declared main.cpp: in function ‘int main(int, char**)’: main.cpp:17:29: error: ‘cythonfunc’ cannot used function    result = cythonfunc(c_rect);                              ^ 

i can success passing separate x0, y0, x1, y1 parameter cythonfunc. there correct way passing cpp struct/object or python object parameter cython public function?

with respect second attempt (which more sensible way of calling c++, although i'd pass reference):

cdef public int cythonfunc(rectangle c_rect):     result = c_rect.getarea()     return result 

the issue doesn't know rectangle is, since cython generated rect.h doesn't include rectangle.h. easiest way fix swap order of includes in main.cpp:

#include "rectangle.h" // 1 first #include "rect.h" 

the error "shapes has not been declared" telling this...

---

with respect first attempt, right have make pyrectangle public. need specify "type object name" cython tells you. shown here (although isn't hugely clear...):

cdef public class pyrectangle [object c_pyrect, type c_pyrect_t]:     # ... before 

this ensures pyrectangle available c/c++ struct c_pyrect (and cythonfunc signature int cythonfunc(struct c_pyrect *);.)

also, python typeobject defining pyrectangle available c_pyrect_t, don't need that.