On: Faster Natural Language Processing in Python

[dr_zoidberg]

Cython is compiled C that uses CPythons objects. If you can distill your algorithm to a full C(ython) implementation, you get CPython objects + C code, which is then compiled with the (appropriate version of the) system compiler.

So for example, from this little Cython code:

    def cy(int x):
        return x + 1

You get the following C code:

    /* Python wrapper */
    static PyObject *__pyx_pw_6hworld_1cy(PyObject *__pyx_self, PyObject *__pyx_arg_x); /*proto*/
    static PyMethodDef __pyx_mdef_6hworld_1cy = {"cy", (PyCFunction)__pyx_pw_6hworld_1cy, METH_O, 0};
    static PyObject *__pyx_pw_6hworld_1cy(PyObject *__pyx_self, PyObject *__pyx_arg_x) {
      int __pyx_v_x;
      PyObject *__pyx_r = 0;
      __Pyx_RefNannyDeclarations
      __Pyx_RefNannySetupContext("cy (wrapper)", 0);
      assert(__pyx_arg_x); {
        __pyx_v_x = __Pyx_PyInt_As_int(__pyx_arg_x); if (unlikely((__pyx_v_x == (int)-1) && PyErr_Occurred())) __PYX_ERR(0, 1, __pyx_L3_error)
      }
      goto __pyx_L4_argument_unpacking_done;
      __pyx_L3_error:;
      __Pyx_AddTraceback("hworld.cy", __pyx_clineno, __pyx_lineno, __pyx_filename);
      __Pyx_RefNannyFinishContext();
      return NULL;
      __pyx_L4_argument_unpacking_done:;
      __pyx_r = __pyx_pf_6hworld_cy(__pyx_self, ((int)__pyx_v_x));

      /* function exit code */
      __Pyx_RefNannyFinishContext();
      return __pyx_r;
    }

    static PyObject *__pyx_pf_6hworld_cy(CYTHON_UNUSED PyObject *__pyx_self, int __pyx_v_x) {
      PyObject *__pyx_r = NULL;
      __Pyx_RefNannyDeclarations
      __Pyx_RefNannySetupContext("cy", 0);
    /* … */
      /* function exit code */
      __pyx_L1_error:;
      __Pyx_XDECREF(__pyx_t_1);
      __Pyx_AddTraceback("hworld.cy", __pyx_clineno, __pyx_lineno, __pyx_filename);
      __pyx_r = NULL;
      __pyx_L0:;
      __Pyx_XGIVEREF(__pyx_r);
      __Pyx_RefNannyFinishContext();
      return __pyx_r;
    }
    /* … */
      __pyx_tuple_ = PyTuple_Pack(2, __pyx_n_s_x, __pyx_n_s_x); if (unlikely(!__pyx_tuple_)) __PYX_ERR(0, 1, __pyx_L1_error)
      __Pyx_GOTREF(__pyx_tuple_);
      __Pyx_GIVEREF(__pyx_tuple_);
    /* … */
      __pyx_t_1 = PyCFunction_NewEx(&__pyx_mdef_6hworld_1cy, NULL, __pyx_n_s_hworld); if (unlikely(!__pyx_t_1)) __PYX_ERR(0, 1, __pyx_L1_error)
      __Pyx_GOTREF(__pyx_t_1);
      if (PyDict_SetItem(__pyx_d, __pyx_n_s_cy, __pyx_t_1) < 0) __PYX_ERR(0, 1, __pyx_L1_error)
      __Pyx_DECREF(__pyx_t_1); __pyx_t_1 = 0;
      __Pyx_XDECREF(__pyx_r);
      __pyx_t_1 = __Pyx_PyInt_From_long((__pyx_v_x + 1)); if (unlikely(!__pyx_t_1)) __PYX_ERR(0, 2, __pyx_L1_error)
      __Pyx_GOTREF(__pyx_t_1);
      __pyx_r = __pyx_t_1;
      __pyx_t_1 = 0;
      goto __pyx_L0;

That compiles and becomes part of a C-extension that you can load with "import module" from within Python.