这一段python程序，为什么结果是这样的

[GCC-pig]

def saver(x=[]):
	x.append(1)
	print(x)
saver([2])
saver()
saver()
saver()

结果
[2, 1]
[1]
[1, 1]
[1, 1, 1]

[mohuanlun]

命名冲突，X就是个变量

[hw7be]

直接copy官方手册内容如下，链接https://docs.python.org/3/tutorial/controlflow.html#more-on-defining-functions Important warning: The default value is evaluated only once. This makes a difference when the default is a mutable object such as a list, dictionary, or instances of most classes. For example, the following function accumulates the arguments passed to it on subsequent calls:

def f(a, L=[]):
    L.append(a)
    return L

print(f(1))
print(f(2))
print(f(3))

This will print

[1]
[1, 2]
[1, 2, 3]

If you don’t want the default to be shared between subsequent calls, you can write the function like this instead:

def f(a, L=None):
    if L is None:
        L = []
    L.append(a)
    return L