when does `__cinit__` been called?

[Jiajun Huang]

hi, all:

    I'm reading <Cython, A Guide for Python Programmers>, and in the chapter 5, section `C-Level Initialization and Finalization`, it says "Cython guarantees that __cinit__ is called exactly once and that it is called before __init, __new__ or alternative Python-level constructors...". But, as far as I know

from libc.stdlib cimport malloc, free

cdef class Matrix:

    cdef:

        unsigned int nrows, ncols

        double *_matrix

    def __cinit__(self, nr, nc):

        print("[__cinit__]id of self: %s" % id(self))

        self.nrows = nr

        self.ncols = nc

        self._matrix = <double *>malloc(nr * nc * sizeof(double))

        if self._matrix == NULL:

            raise MemoryError()

    def __dealloc__(self):

        if self._matrix != NULL:

            free(self._matrix)

    # @classmethod

    # def __new__(cls, nr, nc):

        # print("id of cls: %s" % id(cls))

        # return super().__new__(cls, nr, nc)

    def __init__(self, nr, nc):

        print("[__init__]id of self: %s" % id(self))

the `self` object in `__init__` is the return value of `__new__`. and I've run it:

In [1]: import matrix

In [2]: matrix.Matrix(1, 2)

[__cinit__]id of self: 140461907621872

[__init__]id of self: 140461907621872

Out[2]: <matrix.Matrix at 0x7fbfd61bb7f0>

yes, `__cinit__` is called before `__init__`, but what about `__new__`? we can only get `self` object through `__new__`, right? so is it("Cython guarantees that __cinit__ is called exactly once and that it is called before __init, __new__ or alternative Python-level constructors...") wrong?

[Robert Bradshaw]

__new__ is not yet supported for cdef classes.

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[Jiajun Huang]

thanks. :)

在 2017年1月14日星期六 UTC+8上午1:32:04，Robert Bradshaw写道：