Python ValueError要解压的值太多 - 不是真的吗？

Question

我之前在原因显而易见的地方遇到了这个错误,但我在下面的这个片段中遇到了麻烦.

#!/usr/bin/python

ACL = 'group:troubleshooters:r,user:auto:rx,user:nrpe:r'

for e in ACL.split(','):
  print 'e = "%s"' % e
  print 'type during split = %s' % type(e.split(':'))
  print 'value during split:  %s' % e.split(':')
  print 'number of elements:  %d' % len(e.split(':'))
  for (one, two, three) in e.split(':'):
      print 'one = "%s", two = "%s"' % (one, two)

我已经添加了那些用于调试的print语句,并且已经确认拆分正在生成一个3元素列表,但是当我尝试将它放入3个变量时,我得到:

e = "group:troubleshooters:r"
type during split = <type 'list'>
value during split:  ['group', 'troubleshooters', 'r']
number of elements:  3
Traceback (most recent call last):
  File "/tmp/python_split_test.py", line 10, in <module>
for (one, two, three) in e.split(':'):
ValueError: too many values to unpack

我错过了什么？

Answer 1

也许你应该:

one, two, three = e.split(":")

因为e.split(":")已经是具有三个值的可迭代.

如果你写

for (one, two, three) = something

然后something必须是可迭代的三个值的迭代,例如[[1, 2, 3], [4, 5, 6]]但不是[1, 2, 3].

Answer 2

for (one, two, three) in e.split(':'):

需要e.split()返回一个可迭代列表（例如一个二维列表）。for将迭代列表，并在迭代期间将嵌套列表的每个元素分配给相应的变量。

但e.split()只返回一个字符串列表。您不需要迭代，只需分配它们：

one, two, three = e.split(':')