mathutils_Euler.c

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/*
 *
 * ***** BEGIN GPL LICENSE BLOCK *****
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * The Original Code is Copyright (C) 2001-2002 by NaN Holding BV.
 * All rights reserved.
 *
 *
 * Contributor(s): Joseph Gilbert
 *
 * ***** END GPL LICENSE BLOCK *****
 */

#include <Python.h>

#include "mathutils.h"

#include "BLI_math.h"
#include "BLI_utildefines.h"
#include "BLI_dynstr.h"

#define EULER_SIZE 3

//----------------------------------mathutils.Euler() -------------------
//makes a new euler for you to play with
static PyObject *Euler_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
{
    PyObject *seq = NULL;
    const char *order_str = NULL;

    float eul[EULER_SIZE] = {0.0f, 0.0f, 0.0f};
    short order = EULER_ORDER_XYZ;

    if (kwds && PyDict_Size(kwds)) {
        PyErr_SetString(PyExc_TypeError,
                        "mathutils.Euler(): "
                        "takes no keyword args");
        return NULL;
    }

    if (!PyArg_ParseTuple(args, "|Os:mathutils.Euler", &seq, &order_str))
        return NULL;

    switch (PyTuple_GET_SIZE(args)) {
    case 0:
        break;
    case 2:
        if ((order = euler_order_from_string(order_str, "mathutils.Euler()")) == -1)
            return NULL;
        /* intentionally pass through */
    case 1:
        if (mathutils_array_parse(eul, EULER_SIZE, EULER_SIZE, seq, "mathutils.Euler()") == -1)
            return NULL;
        break;
    }
    return Euler_CreatePyObject(eul, order, Py_NEW, type);
}

/* internal use, assume read callback is done */
static const char *euler_order_str(EulerObject *self)
{
    static const char order[][4] = {"XYZ", "XZY", "YXZ", "YZX", "ZXY", "ZYX"};
    return order[self->order - EULER_ORDER_XYZ];
}

short euler_order_from_string(const char *str, const char *error_prefix)
{
    if ((str[0] && str[1] && str[2] && str[3] == '\0')) {
        switch (*((PY_INT32_T *)str)) {
            case 'X'|'Y'<<8|'Z'<<16:    return EULER_ORDER_XYZ;
            case 'X'|'Z'<<8|'Y'<<16:    return EULER_ORDER_XZY;
            case 'Y'|'X'<<8|'Z'<<16:    return EULER_ORDER_YXZ;
            case 'Y'|'Z'<<8|'X'<<16:    return EULER_ORDER_YZX;
            case 'Z'|'X'<<8|'Y'<<16:    return EULER_ORDER_ZXY;
            case 'Z'|'Y'<<8|'X'<<16:    return EULER_ORDER_ZYX;
        }
    }

    PyErr_Format(PyExc_ValueError,
                 "%s: invalid euler order '%s'",
                 error_prefix, str);
    return -1;
}

/* note: BaseMath_ReadCallback must be called beforehand */
static PyObject *Euler_ToTupleExt(EulerObject *self, int ndigits)
{
    PyObject *ret;
    int i;

    ret = PyTuple_New(EULER_SIZE);

    if (ndigits >= 0) {
        for (i = 0; i < EULER_SIZE; i++) {
            PyTuple_SET_ITEM(ret, i, PyFloat_FromDouble(double_round((double)self->eul[i], ndigits)));
        }
    }
    else {
        for (i = 0; i < EULER_SIZE; i++) {
            PyTuple_SET_ITEM(ret, i, PyFloat_FromDouble(self->eul[i]));
        }
    }

    return ret;
}

//-----------------------------METHODS----------------------------
//return a quaternion representation of the euler

PyDoc_STRVAR(Euler_to_quaternion_doc,
".. method:: to_quaternion()\n"
"\n"
"   Return a quaternion representation of the euler.\n"
"\n"
"   :return: Quaternion representation of the euler.\n"
"   :rtype: :class:`Quaternion`\n"
);
static PyObject *Euler_to_quaternion(EulerObject *self)
{
    float quat[4];

    if (BaseMath_ReadCallback(self) == -1)
        return NULL;

    eulO_to_quat(quat, self->eul, self->order);

    return Quaternion_CreatePyObject(quat, Py_NEW, NULL);
}

//return a matrix representation of the euler
PyDoc_STRVAR(Euler_to_matrix_doc,
".. method:: to_matrix()\n"
"\n"
"   Return a matrix representation of the euler.\n"
"\n"
"   :return: A 3x3 roation matrix representation of the euler.\n"
"   :rtype: :class:`Matrix`\n"
);
static PyObject *Euler_to_matrix(EulerObject *self)
{
    float mat[9];

    if (BaseMath_ReadCallback(self) == -1)
        return NULL;

    eulO_to_mat3((float (*)[3])mat, self->eul, self->order);

    return Matrix_CreatePyObject(mat, 3, 3 , Py_NEW, NULL);
}

PyDoc_STRVAR(Euler_zero_doc,
".. method:: zero()\n"
"\n"
"   Set all values to zero.\n"
);
static PyObject *Euler_zero(EulerObject *self)
{
    zero_v3(self->eul);

    if (BaseMath_WriteCallback(self) == -1)
        return NULL;

    Py_RETURN_NONE;
}

PyDoc_STRVAR(Euler_rotate_axis_doc,
".. method:: rotate_axis(axis, angle)\n"
"\n"
"   Rotates the euler a certain amount and returning a unique euler rotation\n"
"   (no 720 degree pitches).\n"
"\n"
"   :arg axis: single character in ['X, 'Y', 'Z'].\n"
"   :type axis: string\n"
"   :arg angle: angle in radians.\n"
"   :type angle: float\n"
);
static PyObject *Euler_rotate_axis(EulerObject *self, PyObject *args)
{
    float angle = 0.0f;
    int axis; /* actually a character */

    if (!PyArg_ParseTuple(args, "Cf:rotate_axis", &axis, &angle)) {
        PyErr_SetString(PyExc_TypeError,
                        "Euler.rotate_axis(): "
                        "expected an axis 'X', 'Y', 'Z' and an angle (float)");
        return NULL;
    }

    if (!(ELEM3(axis, 'X', 'Y', 'Z'))) {
        PyErr_SetString(PyExc_ValueError,
                        "Euler.rotate_axis(): "
                        "expected axis to be 'X', 'Y' or 'Z'");
        return NULL;
    }

    if (BaseMath_ReadCallback(self) == -1)
        return NULL;


    rotate_eulO(self->eul, self->order, (char)axis, angle);

    (void)BaseMath_WriteCallback(self);

    Py_RETURN_NONE;
}

PyDoc_STRVAR(Euler_rotate_doc,
".. method:: rotate(other)\n"
"\n"
"   Rotates the euler a by another mathutils value.\n"
"\n"
"   :arg other: rotation component of mathutils value\n"
"   :type other: :class:`Euler`, :class:`Quaternion` or :class:`Matrix`\n"
);
static PyObject *Euler_rotate(EulerObject *self, PyObject *value)
{
    float self_rmat[3][3], other_rmat[3][3], rmat[3][3];

    if (BaseMath_ReadCallback(self) == -1)
        return NULL;

    if (mathutils_any_to_rotmat(other_rmat, value, "euler.rotate(value)") == -1)
        return NULL;

    eulO_to_mat3(self_rmat, self->eul, self->order);
    mul_m3_m3m3(rmat, other_rmat, self_rmat);

    mat3_to_compatible_eulO(self->eul, self->eul, self->order, rmat);

    (void)BaseMath_WriteCallback(self);
    Py_RETURN_NONE;
}

PyDoc_STRVAR(Euler_make_compatible_doc,
".. method:: make_compatible(other)\n"
"\n"
"   Make this euler compatible with another,\n"
"   so interpolating between them works as intended.\n"
"\n"
"   .. note:: the rotation order is not taken into account for this function.\n"
);
static PyObject *Euler_make_compatible(EulerObject *self, PyObject *value)
{
    float teul[EULER_SIZE];

    if (BaseMath_ReadCallback(self) == -1)
        return NULL;

    if (mathutils_array_parse(teul, EULER_SIZE, EULER_SIZE, value,
                              "euler.make_compatible(other), invalid 'other' arg") == -1)
    {
        return NULL;
    }

    compatible_eul(self->eul, teul);

    (void)BaseMath_WriteCallback(self);

    Py_RETURN_NONE;
}

//----------------------------Euler.rotate()-----------------------
// return a copy of the euler

PyDoc_STRVAR(Euler_copy_doc,
".. function:: copy()\n"
"\n"
"   Returns a copy of this euler.\n"
"\n"
"   :return: A copy of the euler.\n"
"   :rtype: :class:`Euler`\n"
"\n"
"   .. note:: use this to get a copy of a wrapped euler with\n"
"      no reference to the original data.\n"
);
static PyObject *Euler_copy(EulerObject *self)
{
    if (BaseMath_ReadCallback(self) == -1)
        return NULL;

    return Euler_CreatePyObject(self->eul, self->order, Py_NEW, Py_TYPE(self));
}

//----------------------------print object (internal)--------------
//print the object to screen

static PyObject *Euler_repr(EulerObject *self)
{
    PyObject *ret, *tuple;

    if (BaseMath_ReadCallback(self) == -1)
        return NULL;

    tuple = Euler_ToTupleExt(self, -1);

    ret = PyUnicode_FromFormat("Euler(%R, '%s')", tuple, euler_order_str(self));

    Py_DECREF(tuple);
    return ret;
}

static PyObject *Euler_str(EulerObject *self)
{
    DynStr *ds;

    if (BaseMath_ReadCallback(self) == -1)
        return NULL;

    ds = BLI_dynstr_new();

    BLI_dynstr_appendf(ds, "<Euler (x=%.4f, y=%.4f, z=%.4f), order='%s'>",
                       self->eul[0], self->eul[1], self->eul[2], euler_order_str(self));

    return mathutils_dynstr_to_py(ds); /* frees ds */
}

static PyObject *Euler_richcmpr(PyObject *a, PyObject *b, int op)
{
    PyObject *res;
    int ok = -1; /* zero is true */

    if (EulerObject_Check(a) && EulerObject_Check(b)) {
        EulerObject *eulA = (EulerObject *)a;
        EulerObject *eulB = (EulerObject *)b;

        if (BaseMath_ReadCallback(eulA) == -1 || BaseMath_ReadCallback(eulB) == -1)
            return NULL;

        ok = ((eulA->order == eulB->order) && EXPP_VectorsAreEqual(eulA->eul, eulB->eul, EULER_SIZE, 1)) ? 0 : -1;
    }

    switch (op) {
    case Py_NE:
        ok = !ok; /* pass through */
    case Py_EQ:
        res = ok ? Py_False : Py_True;
        break;

    case Py_LT:
    case Py_LE:
    case Py_GT:
    case Py_GE:
        res = Py_NotImplemented;
        break;
    default:
        PyErr_BadArgument();
        return NULL;
    }

    return Py_INCREF(res), res;
}

//---------------------SEQUENCE PROTOCOLS------------------------
//----------------------------len(object)------------------------
//sequence length
static int Euler_len(EulerObject *UNUSED(self))
{
    return EULER_SIZE;
}
//----------------------------object[]---------------------------
//sequence accessor (get)
static PyObject *Euler_item(EulerObject *self, int i)
{
    if (i < 0) i = EULER_SIZE - i;

    if (i < 0 || i >= EULER_SIZE) {
        PyErr_SetString(PyExc_IndexError,
                        "euler[attribute]: "
                        "array index out of range");
        return NULL;
    }

    if (BaseMath_ReadIndexCallback(self, i) == -1)
        return NULL;

    return PyFloat_FromDouble(self->eul[i]);

}
//----------------------------object[]-------------------------
//sequence accessor (set)
static int Euler_ass_item(EulerObject *self, int i, PyObject *value)
{
    float f = PyFloat_AsDouble(value);

    if (f == -1 && PyErr_Occurred()) { // parsed item not a number
        PyErr_SetString(PyExc_TypeError,
                        "euler[attribute] = x: "
                        "argument not a number");
        return -1;
    }

    if (i < 0) i = EULER_SIZE - i;

    if (i < 0 || i >= EULER_SIZE) {
        PyErr_SetString(PyExc_IndexError,
                        "euler[attribute] = x: "
                        "array assignment index out of range");
        return -1;
    }

    self->eul[i] = f;

    if (BaseMath_WriteIndexCallback(self, i) == -1)
        return -1;

    return 0;
}
//----------------------------object[z:y]------------------------
//sequence slice (get)
static PyObject *Euler_slice(EulerObject *self, int begin, int end)
{
    PyObject *tuple;
    int count;

    if (BaseMath_ReadCallback(self) == -1)
        return NULL;

    CLAMP(begin, 0, EULER_SIZE);
    if (end < 0) end = (EULER_SIZE + 1) + end;
    CLAMP(end, 0, EULER_SIZE);
    begin = MIN2(begin, end);

    tuple = PyTuple_New(end - begin);
    for (count = begin; count < end; count++) {
        PyTuple_SET_ITEM(tuple, count - begin, PyFloat_FromDouble(self->eul[count]));
    }

    return tuple;
}
//----------------------------object[z:y]------------------------
//sequence slice (set)
static int Euler_ass_slice(EulerObject *self, int begin, int end, PyObject *seq)
{
    int i, size;
    float eul[EULER_SIZE];

    if (BaseMath_ReadCallback(self) == -1)
        return -1;

    CLAMP(begin, 0, EULER_SIZE);
    if (end < 0) end = (EULER_SIZE + 1) + end;
    CLAMP(end, 0, EULER_SIZE);
    begin = MIN2(begin, end);

    if ((size = mathutils_array_parse(eul, 0, EULER_SIZE, seq, "mathutils.Euler[begin:end] = []")) == -1)
        return -1;

    if (size != (end - begin)) {
        PyErr_SetString(PyExc_ValueError,
                        "euler[begin:end] = []: "
                        "size mismatch in slice assignment");
        return -1;
    }

    for (i = 0; i < EULER_SIZE; i++)
        self->eul[begin + i] = eul[i];

    (void)BaseMath_WriteCallback(self);
    return 0;
}

static PyObject *Euler_subscript(EulerObject *self, PyObject *item)
{
    if (PyIndex_Check(item)) {
        Py_ssize_t i;
        i = PyNumber_AsSsize_t(item, PyExc_IndexError);
        if (i == -1 && PyErr_Occurred())
            return NULL;
        if (i < 0)
            i += EULER_SIZE;
        return Euler_item(self, i);
    }
    else if (PySlice_Check(item)) {
        Py_ssize_t start, stop, step, slicelength;

        if (PySlice_GetIndicesEx((void *)item, EULER_SIZE, &start, &stop, &step, &slicelength) < 0)
            return NULL;

        if (slicelength <= 0) {
            return PyTuple_New(0);
        }
        else if (step == 1) {
            return Euler_slice(self, start, stop);
        }
        else {
            PyErr_SetString(PyExc_IndexError,
                            "slice steps not supported with eulers");
            return NULL;
        }
    }
    else {
        PyErr_Format(PyExc_TypeError,
                     "euler indices must be integers, not %.200s",
                     Py_TYPE(item)->tp_name);
        return NULL;
    }
}


static int Euler_ass_subscript(EulerObject *self, PyObject *item, PyObject *value)
{
    if (PyIndex_Check(item)) {
        Py_ssize_t i = PyNumber_AsSsize_t(item, PyExc_IndexError);
        if (i == -1 && PyErr_Occurred())
            return -1;
        if (i < 0)
            i += EULER_SIZE;
        return Euler_ass_item(self, i, value);
    }
    else if (PySlice_Check(item)) {
        Py_ssize_t start, stop, step, slicelength;

        if (PySlice_GetIndicesEx((void *)item, EULER_SIZE, &start, &stop, &step, &slicelength) < 0)
            return -1;

        if (step == 1)
            return Euler_ass_slice(self, start, stop, value);
        else {
            PyErr_SetString(PyExc_IndexError,
                            "slice steps not supported with euler");
            return -1;
        }
    }
    else {
        PyErr_Format(PyExc_TypeError,
                     "euler indices must be integers, not %.200s",
                     Py_TYPE(item)->tp_name);
        return -1;
    }
}

//-----------------PROTCOL DECLARATIONS--------------------------
static PySequenceMethods Euler_SeqMethods = {
    (lenfunc) Euler_len,                    /* sq_length */
    (binaryfunc) NULL,                      /* sq_concat */
    (ssizeargfunc) NULL,                    /* sq_repeat */
    (ssizeargfunc) Euler_item,              /* sq_item */
    (ssizessizeargfunc) NULL,               /* sq_slice, deprecated  */
    (ssizeobjargproc) Euler_ass_item,       /* sq_ass_item */
    (ssizessizeobjargproc) NULL,            /* sq_ass_slice, deprecated */
    (objobjproc) NULL,                      /* sq_contains */
    (binaryfunc) NULL,                      /* sq_inplace_concat */
    (ssizeargfunc) NULL,                    /* sq_inplace_repeat */
};

static PyMappingMethods Euler_AsMapping = {
    (lenfunc)Euler_len,
    (binaryfunc)Euler_subscript,
    (objobjargproc)Euler_ass_subscript
};

/* euler axis, euler.x/y/z */

PyDoc_STRVAR(Euler_axis_doc,
"Euler axis angle in radians.\n\n:type: float"
);
static PyObject *Euler_axis_get(EulerObject *self, void *type)
{
    return Euler_item(self, GET_INT_FROM_POINTER(type));
}

static int Euler_axis_set(EulerObject *self, PyObject *value, void *type)
{
    return Euler_ass_item(self, GET_INT_FROM_POINTER(type), value);
}

/* rotation order */

PyDoc_STRVAR(Euler_order_doc,
"Euler rotation order.\n\n:type: string in ['XYZ', 'XZY', 'YXZ', 'YZX', 'ZXY', 'ZYX']"
);
static PyObject *Euler_order_get(EulerObject *self, void *UNUSED(closure))
{
    if (BaseMath_ReadCallback(self) == -1) /* can read order too */
        return NULL;

    return PyUnicode_FromString(euler_order_str(self));
}

static int Euler_order_set(EulerObject *self, PyObject *value, void *UNUSED(closure))
{
    const char *order_str = _PyUnicode_AsString(value);
    short order = euler_order_from_string(order_str, "euler.order");

    if (order == -1)
        return -1;

    self->order = order;
    (void)BaseMath_WriteCallback(self); /* order can be written back */
    return 0;
}

/*****************************************************************************/
/* Python attributes get/set structure:                                      */
/*****************************************************************************/
static PyGetSetDef Euler_getseters[] = {
    {(char *)"x", (getter)Euler_axis_get, (setter)Euler_axis_set, Euler_axis_doc, (void *)0},
    {(char *)"y", (getter)Euler_axis_get, (setter)Euler_axis_set, Euler_axis_doc, (void *)1},
    {(char *)"z", (getter)Euler_axis_get, (setter)Euler_axis_set, Euler_axis_doc, (void *)2},
    {(char *)"order", (getter)Euler_order_get, (setter)Euler_order_set, Euler_order_doc, (void *)NULL},

    {(char *)"is_wrapped", (getter)BaseMathObject_is_wrapped_get, (setter)NULL, BaseMathObject_is_wrapped_doc, NULL},
    {(char *)"owner", (getter)BaseMathObject_owner_get, (setter)NULL, BaseMathObject_owner_doc, NULL},
    {NULL, NULL, NULL, NULL, NULL}  /* Sentinel */
};


//-----------------------METHOD DEFINITIONS ----------------------
static struct PyMethodDef Euler_methods[] = {
    {"zero", (PyCFunction) Euler_zero, METH_NOARGS, Euler_zero_doc},
    {"to_matrix", (PyCFunction) Euler_to_matrix, METH_NOARGS, Euler_to_matrix_doc},
    {"to_quaternion", (PyCFunction) Euler_to_quaternion, METH_NOARGS, Euler_to_quaternion_doc},
    {"rotate_axis", (PyCFunction) Euler_rotate_axis, METH_VARARGS, Euler_rotate_axis_doc},
    {"rotate", (PyCFunction) Euler_rotate, METH_O, Euler_rotate_doc},
    {"make_compatible", (PyCFunction) Euler_make_compatible, METH_O, Euler_make_compatible_doc},
    {"__copy__", (PyCFunction) Euler_copy, METH_NOARGS, Euler_copy_doc},
    {"copy", (PyCFunction) Euler_copy, METH_NOARGS, Euler_copy_doc},
    {NULL, NULL, 0, NULL}
};

//------------------PY_OBECT DEFINITION--------------------------
PyDoc_STRVAR(euler_doc,
"This object gives access to Eulers in Blender."
);
PyTypeObject euler_Type = {
    PyVarObject_HEAD_INIT(NULL, 0)
    "mathutils.Euler",              //tp_name
    sizeof(EulerObject),            //tp_basicsize
    0,                              //tp_itemsize
    (destructor)BaseMathObject_dealloc,     //tp_dealloc
    NULL,                           //tp_print
    NULL,                           //tp_getattr
    NULL,                           //tp_setattr
    NULL,                           //tp_compare
    (reprfunc) Euler_repr,          //tp_repr
    NULL,                           //tp_as_number
    &Euler_SeqMethods,              //tp_as_sequence
    &Euler_AsMapping,               //tp_as_mapping
    NULL,                           //tp_hash
    NULL,                           //tp_call
    (reprfunc) Euler_str,           //tp_str
    NULL,                           //tp_getattro
    NULL,                           //tp_setattro
    NULL,                           //tp_as_buffer
    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HAVE_GC, //tp_flags
    euler_doc, //tp_doc
    (traverseproc)BaseMathObject_traverse,  //tp_traverse
    (inquiry)BaseMathObject_clear,  //tp_clear
    (richcmpfunc)Euler_richcmpr,    //tp_richcompare
    0,                              //tp_weaklistoffset
    NULL,                           //tp_iter
    NULL,                           //tp_iternext
    Euler_methods,                  //tp_methods
    NULL,                           //tp_members
    Euler_getseters,                //tp_getset
    NULL,                           //tp_base
    NULL,                           //tp_dict
    NULL,                           //tp_descr_get
    NULL,                           //tp_descr_set
    0,                              //tp_dictoffset
    NULL,                           //tp_init
    NULL,                           //tp_alloc
    Euler_new,                      //tp_new
    NULL,                           //tp_free
    NULL,                           //tp_is_gc
    NULL,                           //tp_bases
    NULL,                           //tp_mro
    NULL,                           //tp_cache
    NULL,                           //tp_subclasses
    NULL,                           //tp_weaklist
    NULL                            //tp_del
};
//------------------------Euler_CreatePyObject (internal)-------------
//creates a new euler object
/*pass Py_WRAP - if vector is a WRAPPER for data allocated by BLENDER
 (i.e. it was allocated elsewhere by MEM_mallocN())
  pass Py_NEW - if vector is not a WRAPPER and managed by PYTHON
 (i.e. it must be created here with PyMEM_malloc())*/
PyObject *Euler_CreatePyObject(float *eul, short order, int type, PyTypeObject *base_type)
{
    EulerObject *self;

    self = base_type ?  (EulerObject *)base_type->tp_alloc(base_type, 0) :
                        (EulerObject *)PyObject_GC_New(EulerObject, &euler_Type);

    if (self) {
        /* init callbacks as NULL */
        self->cb_user = NULL;
        self->cb_type = self->cb_subtype = 0;

        if (type == Py_WRAP) {
            self->eul = eul;
            self->wrapped = Py_WRAP;
        }
        else if (type == Py_NEW) {
            self->eul = PyMem_Malloc(EULER_SIZE * sizeof(float));
            if (eul) {
                copy_v3_v3(self->eul, eul);
            }
            else {
                zero_v3(self->eul);
            }

            self->wrapped = Py_NEW;
        }
        else {
            Py_FatalError("Euler(): invalid type!");
        }

        self->order = order;
    }

    return (PyObject *)self;
}

PyObject *Euler_CreatePyObject_cb(PyObject *cb_user, short order, int cb_type, int cb_subtype)
{
    EulerObject *self = (EulerObject *)Euler_CreatePyObject(NULL, order, Py_NEW, NULL);
    if (self) {
        Py_INCREF(cb_user);
        self->cb_user =         cb_user;
        self->cb_type =         (unsigned char)cb_type;
        self->cb_subtype =      (unsigned char)cb_subtype;
        PyObject_GC_Track(self);
    }

    return (PyObject *)self;
}