python - 如何比较两个 ctypes 对象是否相等？

Question

import ctypes as ct

class Point(ct.Structure):
    _fields_ = [
        ('x', ct.c_int),
        ('y', ct.c_int),
    ]

p1 = Point(10, 10)
p2 = Point(10, 10)

print p1 == p2 # => False

相等运算符 '==' 在上面的简单情况下给出 False。有什么直接的方法吗？

编辑:

这里有一个稍微改进的版本(基于已接受的答案)，它也可以处理嵌套数组:

import ctypes as ct

class CtStruct(ct.Structure):

    def __eq__(self, other):
        for field in self._fields_:
            attr_name = field[0]
            a, b = getattr(self, attr_name), getattr(other, attr_name)
            is_array = isinstance(a, ct.Array)
            if is_array and a[:] != b[:] or not is_array and a != b:
                return False
        return True

    def __ne__(self, other):
        for field in self._fields_:
            attr_name = field[0]
            a, b = getattr(self, attr_name), getattr(other, attr_name)
            is_array = isinstance(a, ct.Array)
            if is_array and a[:] != b[:] or not is_array and a != b:
                return True
        return False

class Point(CtStruct):
    _fields_ = [
        ('x', ct.c_int),
        ('y', ct.c_int),
        ('arr', ct.c_int * 2),
    ]

p1 = Point(10, 20, (30, 40))
p2 = Point(10, 20, (30, 40))

print p1 == p2 # True

Answer 1

创建一个类MyCtStructure，那么它的所有子类都不需要实现__eq__ & __ne__。在您的案例中，定义 eq 不再是一件乏味的工作。

import ctypes as ct
class MyCtStructure(ct.Structure):

    def __eq__(self, other):
        for fld in self._fields_:
            if getattr(self, fld[0]) != getattr(other, fld[0]):
                return False
        return True

    def __ne__(self, other):
        for fld in self._fields_:
            if getattr(self, fld[0]) != getattr(other, fld[0]):
                return True
        return False

class Point(MyCtStructure):
    _fields_ = [
        ('x', ct.c_int),
        ('y', ct.c_int),
    ]


p1 = Point(10, 11)
p2 = Point(10, 11)

print p1 == p2