使用Cython将结构从C返回到Python [英] Return a struct from C to Python using Cython

问题描述

我正在尝试将结构从c文件传递回Python。假设我有一个文件pointc.c，如下所示：

I am trying to pass a struct back into my Python from a c file. Let's say I have a file pointc.c like this:

typedef struct Point {
    int x;
    int y;
} Point;

struct Point make_and_send_point(int x, int y);

struct Point make_and_send_point(int x, int y) {
    struct Point p = {x, y};
    return p;
}

然后我像这样设置一个point.pyx文件：

Then I set-up a point.pyx file like this:

"# distutils: language = c"
# distutils: sources = pointc.c

cdef struct Point:
    int x
    int y

cdef extern from "pointc.c":
    Point make_and_send_point(int x, int y)

def make_point(int x, int y):
    return make_and_send_point(x, y) // This won't work, but compiles without the 'return' in-front of the function call

如何将返回的结构放入Python？这种事情是否只有通过在Cython中创建结构并通过引用void c函数进行发送才能实现？

How do I get the returned struct into my Python? Is this kind of thing only possible by creating a struct in the Cython and sending by reference to a void c function?

作为参考，我的setup.py是：

As a reference, my setup.py is:

from distutils.core import setup, Extension
from Cython.Build import cythonize

setup(ext_modules = cythonize(
      "point.pyx",
      language="c"
     )
)

推荐答案

通常，您通常会编写某种包含c级结构的包装器类，例如：

Most typically you would write some kind of wrapper class that holds the c-level struct, for example:

# point.pyx
cdef extern from "pointc.c":
    ctypedef struct Point:
        int x
        int y
    Point make_and_send_point(int x, int y)

cdef class PyPoint:
    cdef Point p

    def __init__(self, x, y):
        self.p = make_and_send_point(x, y)

    @property
    def x(self):
       return self.p.x

    @property
    def y(self):
        return self.p.y

使用情况

>>> import point
>>> p = point.PyPoint(10, 10)
>>> p.x
10

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