Cython：我们如何正确调用加、减、乘和除运算符？

Question

在.pxd文件中，我写了

    _Point operator+(const _Point other) const
    _Point operator -(const _Point other) const
    bool operator==(const _Point other) const

在.pyx文件中，我写了

def __eq__(self, Point other):
    cdef _Point* selfptr = self.c_point.get()
    cdef _Point* otherptr = other.c_point.get()
    return selfptr[0] == otherptr[0]

但是对于像

__add__

这样的运营商来说，我不能像

==

那样做同样的事情。

def __add__(self, Point other):
    cdef _Point * selfptr = self.c_point.get()
    cdef _Point * otherptr = other.c_point.get()
    return selfptr[0] + otherptr[0]

错误信息

    × python setup.py egg_info did not run successfully.
      │ exit code: 1
      ╰─> [27 lines of output]
          
          Error compiling Cython file:
          ------------------------------------------------------------
          ...
                  return not self.__eq__(other)
          
              def __add__(self, Point other):
                  cdef _Point * selfptr = self.c_point.get()
                  cdef _Point * otherptr = other.c_point.get()
                  return selfptr[0] + otherptr[0]
                                    ^
          ------------------------------------------------------------
          
          src/Geometry/Point/Point.pyx:170:26: Cannot convert '_Point' to Python object

我该如何解决这个问题？谢谢你

Answer 1

错误只是指出返回的

_Point

不是Python对象，你必须将其包装在Python对象中，一种方法是构造另一个PyPoint并替换其指针。

%%cython -c=-std=c++20 --cplus -a

cdef extern from *:
    """
    class Value
    {
      public:
      int m_val;
      Value(): m_val(0) {}
      Value(int val): m_val(val) {}
      Value operator+(const Value& other) const { return m_val + other.m_val;} 
    };
    """

    cdef cppclass Value:
        Value() noexcept
        Value(int) noexcept
        Value operator+(const Value&) const
        Value(Value) noexcept

cdef class PyValue:
    cdef Value* val

    def __init__(self):
      val = new Value(0)

    def __add__(self, PyValue other):
      ret_val = PyValue()
      del ret_val.val
      ret_val.val = new Value(self.val[0] + other.val[0])
      return ret_val