Question

我有多个python类。其中一个类（例如，class1）的对象中包含大量数据（在运行时不会更改）。另一个类（例如class2）具有一个成员变量，该成员变量映射到class1的一个对象。假设class1和class2具有其他可变成员和不可变成员变量。

现在我也想对class2的对象进行深层复制。它还将对class2中的class1对象进行深度复制。但为了节省内存，我想避免这种情况。我该怎么做呢？

class class1:
    def __init__(self):
        self.largeData = None
        self.mutableVar = None
        self.immutableVar = None


class class2:
    def __init__(self, objc1: class1):
        self.objc1 = objc1  # of the type class1
        self.mutableVar = None
        self.immutableVar = None


c1_1 = class1()
c1_2 = class1()

c2_1 = class2(c1_1)

c2_1Copy = copy.deepcopy(c2_1)
# i want c2_1Copy to reference the same objc1 as c2_1,
# but different mutablevar and immutablevar

c2_2 = class2(c1_2)  # Note: cannot use static variable

请帮助我...
在此先感谢

Answer 1

使用__deepcopy__挂钩方法自定义对象的深层复制方式。

import copy


class LargeDataContainer:
    def __init__(self):
        self.data = "x" * 800


class Thing:
    def __init__(self, large_data: LargeDataContainer):
        self.large_data = large_data
        self.x = [1, 2, 3]

    def __deepcopy__(self, memo):
        new_inst = type(self).__new__(self.__class__)  # skips calling __init__
        new_inst.large_data = self.large_data  # just assign

        # rinse and repeat this for other attrs that need to be deepcopied:
        new_inst.x = copy.deepcopy(self.x, memo)
        return new_inst


ldc = LargeDataContainer()

t1 = Thing(ldc)
t2 = copy.deepcopy(t1)
assert t1 is not t2
assert t1.large_data is t2.large_data
assert t1.x is not t2.x

如何在python中选择性地进行深度复制？

1 个答案: