关于python：为什么这些列表相同？

Why are these lists the same?

我不明白x和y是如何构成同一个列表的。我一直试图用print语句和import code; code.interact(local=locals())来调试它，但我不知道到底发生了什么：-(

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from collections import namedtuple, OrderedDict

coordinates_2d=["x","y"]

def virtual_container(virtual_container, objects_type):
"""Used to create a virtual object given a the type of container and what it holds.
The object_type needs to only have normal values."""
if issubclass(virtual_container, list):
class my_virtual_container_class:
"""This singleton class represents the container"""
def __init__(self):
#Define the default values
__vals__=OrderedDict([(key,list()) for key in objects_type])
print(id(__vals__["x"]), id(__vals__["y"]))#ids are different: 12911896 12911968
#Then functions to access them
d={key: lambda self: self.__vals__[key] for key in objects_type}
d["__vals__"]=__vals__
#Construct a named tuple from this
self.attr=type('attr_cl',(), d)()
print(id(self.attr.x()), id(self.attr.y()))#ids are same: 32904544 32904544
#TODO: Define the operators __del__, setitem, getitem. Also append
return my_virtual_container_class()

#Nice method of handling coordinates
coordinates=virtual_container(list, coordinates_2d)
x=coordinates.attr.x()
y=coordinates.attr.y()
x.append(1)
y.append(2)
print(x, y)#Prints [1, 2] [1, 2]

相关讨论

这一行有问题：

1	d={key: lambda self: self.__vals__[key] for key in objects_type}

lambda使用变量EDOCX1的值(0)，但该值在调用lambda时已发生更改，因此所有lambda实际上都将对键使用相同的值。

这可以通过一个小技巧来解决：将键作为默认参数值传递给lambda：

1	... lambda self, key=key: self.__vals__[key] ...

这样可以确保EDOCX1的值(0)与创建lambda时的值绑定在一起。