用Cython包装C ++类时处理指针

问题描述

使用cython处理指针时遇到麻烦.该类的cython实现包含指向类Person的C ++实例的指针.这是我的.pyx文件:

I'm having trouble when handling pointers with cython. The cython implementation of the class holds a pointer to a C++ instance of class Person. Here's my .pyx file:

person.pyx

cdef class PyPerson:
    cdef Person *pointer

    def __cinit__(self):
        self.pointer=new Person()

    def set_parent(self, PyPerson father):
        cdef Person new_father=*(father.pointer)
        self.c_person.setParent(new_father)

C ++方法setParent将Person对象作为参数.由于PyPerson类的属性pointer是指向Person对象的指针，因此我认为我可以使用*(PyPersonObject.pointer)语法使用*pointer所指向的地址来获取该对象.但是，当我尝试编译它时，出现以下错误

The C++ method setParent takes a Person object as an argument. Since the attribute pointer of the PyPerson class is a pointer to a Person object, I thought that I could get the object at the adress pointed by *pointer with the syntax *(PyPersonObject.pointer). However when I try to compile it I get the following error

 def set_parent(self, PyPerson father):
    cdef Person new_father=*(father.pointer)
                             ^
------------------------------------------------------------

person.pyx:51:30: Cannot assign type 'Person *' to 'Person'

有人知道我该如何到达指针的地址?当我在C ++程序中执行相同操作时，不会出现任何错误.这是C ++类的实现，以备不时之需:

Does someone knows how can I get to the object at the adress of the pointer?When I do the same in a C++ program I get no error. Here's the implementation of the C++ class in case you want to see it :

person.cpp

Person::Person():parent(NULL){
}

Person::setParent(Person &p){
     parent=&p;
}

注意:由于涉及完整类的其他原因，我无法通过持有Person实例(cdef Peron not_pointer)来解决该问题.

NOTE: I can't solve it by holding a Person instance (cdef Peron not_pointer) for other reasons involving the complete class.

推荐答案

我应该阅读有关将C ++与Cython结合使用的整个cython文档.对于那些不知道的人，不能在Cython中使用解引用运算符*.相反，您需要从cython.operator模块导入dereference.当您要访问指定地址的对象时，应输入dereference(pointer).

I should have read the entire cython docs on using C++ with Cython. For those who don't know, the dereference operator* can't be used in Cython. Instead you need to import dereference from the cython.operator module. When you want to access the object at the pointed address, you should write dereference(pointer).

具体来说，我的问题的答案是写cdef Person new_father=dereference(father.c_person).

In concrete, the answer to my problem is to write cdef Person new_father=dereference(father.c_person).

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