为C ++编译时无法使Cython工作

Question

I'm trying do a simple example to cythonize a c++ Test class. I can't get it to work, why?

Here is my code, very basic:

mytest.h:

class Test
{
public:
    Test(unsigned test = 0);

    void print();
private:
    unsigned m_test;

};

mytest.cpp:

#include "mytest.h"
#include <iostream>
using namespace std;

Test::Test(unsigned test)
: m_test(test)
{
  cout << "Test::Test" << endl;
}
void Test::print()
{
  cout << "print:" << m_test << endl;
}

For the Cython part, I have, test.pyx :

cdef extern from "mytest.h":
  cdef cppclass Test:
    Test(unsigned int) except +
    void print()

cdef class pyTest:
  cdef Test* thisptr
    def __cinit__(self, unsigned test):
    self.thisptr = new Test(test)
  def __dealloc__(self):
    del self.thisptr

And i compile with:

cython --cplus test.pyx

... And get a ton of error messages, like "Empty declarator":

> Error compiling Cython file:
> ------------------------------------------------------------
> ...
> cdef extern from "mytest.h":
>         cdef cppclass Test:
>                 Test(unsigned int) except +
>                 void print()
>       ^
> ------------------------------------------------------------
>  
> test.pyx:4:7: Empty declarator
> 
> Error compiling Cython file:
> ------------------------------------------------------------
> ...
> cdef extern from "mytest.h":
>         cdef cppclass Test:
>                 Test(unsigned int) except +
>                 void print()
>       ^
> ------------------------------------------------------------
>
> test.pyx:4:7: Syntax error in C variable declaration

What am I not seeing ?

Thanks

Answer 1

I've been where you are few weeks ago. Since I am a new user of Cython as well, I can't say for sure, but giving following advice.

You may want to put following lines at the top of your .pyx file (very easy to ignore in Cython tutorial)

# distutils: language = c++
# distutils: sources = mytest.cpp.

And for compile command, you can use:

cython -a test.pyx --cplus

Hope it helps. :)

Answer 2

I had exactly the same problem a few days ago. The issue is with the name of your print() method. For some reason, which I dont know exactly, cython doesn't like print(). If you change it to any other name, like printtest(). It will compile just fine.