Cython：使用原始指针进行重载构造函数初始化

Question

我试图包装两个C++类：Cluster和ClusterTree。ClusterTree有一个方法get_current_cluster()，它实例化一个集群对象，并返回对它的引用。ClusterTree拥有集群对象，并在C++中管理其创建和删除。

我用cython包装了Cluster，生成了PyCluster。

PyCluster应该有两种创建方式：

1）通过传入两个数组，这意味着Python应该通过直接传入一个原始C++指针（由ClusterTree的get_current_cluster())创建）来自动处理删除（通过__dealloc___
2)。

from libcpp cimport bool
from libcpp.vector cimport vector

cdef extern from "../include/Cluster.h" namespace "Terran":
    cdef cppclass Cluster:
        Cluster(vector[vector[double]],vector[int]) except +

cdef class PyCluster:
    cdef Cluster* __thisptr
    __autoDelete = True

    def __cinit__(self, vector[vector[double]] data, vector[int] period):
        self.__thisptr = new Cluster(data, period)  

    @classmethod
    def __constructFromRawPointer(self, raw_ptr):
        self.__thisptr = raw_ptr
        self.__autoDelete = False

    def __dealloc__(self):
        if self.__autoDelete:
            del self.__thisptr

cdef extern from "../include/ClusterTree.h" namespace "Terran":
    cdef cppclass ClusterTree:
        ClusterTree(vector[vector[double]],vector[int]) except +
        Cluster& getCurrentCluster()

cdef class PyClusterTree:

    cdef ClusterTree *__thisptr

    def __cinit__(self, vector[vector[double]] data, vector[int] period):
        self.__thisptr = new ClusterTree(data,period)

    def __dealloc__(self):
        del self.__thisptr

    def get_current_cluster(self):

        cdef Cluster* ptr = &(self.__thisptr.getCurrentCluster())
        return PyCluster.__constructFromRawPointer(ptr)

这导致：

Error compiling Cython file:
------------------------------------------------------------
...
    def get_current_cluster(self):
        cdef Cluster* ptr = &(self.__thisptr.getCurrentCluster())
        return PyCluster.__constructFromRawPointer(ptr)
                                                     ^
------------------------------------------------------------

terran.pyx:111:54: Cannot convert 'Cluster *' to Python object

注我不能cdef__init__或@classmethods。

Answer 1

指针只能作为参数传递给cdef函数，而cinit必须是def函数。但是提供一个classmethod几乎是要走的路！

cdef Cluster* __thisptr
cdef bool __wrapped  ## defaults to False

@staticmethod
cdef PyCluster wrap(Cluster* ptr):
    cdef PyCluster pc = PyCluster([], [])  ## Initialize as cheaply as possible
    del pc.__thisptr  ## delete the old pointer to avoid memory leaks!
    pc.__thisptr = ptr
    pc.__wrapped = True
    return pc