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Why does Cython use PyObjects for very simple expressions?

asked 2012-04-03 23:09:19 +0200

chaesloc2 gravatar image

updated 2012-04-03 23:45:32 +0200


cimport cython
def f():
    cdef long a


  /* "_data_programfiles__sage_sage_notebook_sagenb_home_admin_1_code_sage119_spyx_0.pyx":12
 * def f():
 *     cdef long a
 *     a=long(1.5)             # <<<<<<<<<<<<<<
  __pyx_t_1 = PyFloat_FromDouble(1.5); if (unlikely(!__pyx_t_1)) {__pyx_filename = __pyx_f[0]; __pyx_lineno = 12; __pyx_clineno = __LINE__; goto __pyx_L1_error;}
  __pyx_t_2 = PyTuple_New(1); if (unlikely(!__pyx_t_2)) {__pyx_filename = __pyx_f[0]; __pyx_lineno = 12; __pyx_clineno = __LINE__; goto __pyx_L1_error;}
  __Pyx_GOTREF(((PyObject *)__pyx_t_2));
  PyTuple_SET_ITEM(__pyx_t_2, 0, __pyx_t_1);
  __pyx_t_1 = 0;
  __pyx_t_1 = PyObject_Call(((PyObject *)((PyObject*)(&PyLong_Type))), ((PyObject *)__pyx_t_2), NULL); if (unlikely(!__pyx_t_1)) {__pyx_filename = __pyx_f[0]; __pyx_lineno = 12; __pyx_clineno = __LINE__; goto __pyx_L1_error;}
  __Pyx_DECREF(((PyObject *)__pyx_t_2)); __pyx_t_2 = 0;
  __pyx_t_3 = __Pyx_PyInt_AsLong(__pyx_t_1); if (unlikely((__pyx_t_3 == (long)-1) && PyErr_Occurred())) {__pyx_filename = __pyx_f[0]; __pyx_lineno = 12; __pyx_clineno = __LINE__; goto __pyx_L1_error;}
  __Pyx_DECREF(__pyx_t_1); __pyx_t_1 = 0;
  __pyx_v_a = __pyx_t_3;

Why is the c code so complicated? I expected something like "__pyx_v_a=long(1.5);" Is there any way I can avoid all the PyObjects? (I don't need to, but I managed to do so in the rest of my code)

EDIT: So one way seems to be to 'cdef extern from "math.h" \n long floor(double x)'.

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answered 2012-04-04 03:25:38 +0200

Jason Grout gravatar image


cimport cython
def f():
    cdef long a

I think the problem is that you are calling the python long function. Instead, you can either do the above (or use your floor idea).

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Asked: 2012-04-03 23:09:19 +0200

Seen: 1,835 times

Last updated: Apr 04 '12