[英]syntax error on nonlocal statement in Python
I would like to test the example of the use of the nonlocal statement specified in the answer on this question: 我想测试在此问题的答案中指定的使用非本地语句的示例:
def outer():
x = 1
def inner():
nonlocal x
x = 2
print("inner:", x)
inner()
print("outer:", x)
but when I try to load this code, I always get a syntax error: 但是当我尝试加载此代码时,总是会出现语法错误:
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "t.py", line 4
nonlocal x
^
SyntaxError: invalid syntax
Does anybody know what I am doing wrong here (I get the syntax error for every example that I use, containing nonlocal
). 有人知道我在这里做错了吗(我使用的每个示例都包含
nonlocal
的语法错误。)
nonlocal
only works in Python 3; nonlocal
仅适用于Python 3; it is a new addition to the language . 这是该语言的一种新增加 。
In Python 2 it'll raise a syntax error; 在Python 2中,它将引发语法错误; python sees
nonlocal
as part of an expression instead of a statement. python将
nonlocal
视为表达式的一部分,而不是语句。
This specific example works just fine when you actually use the correct Python version: 当您实际使用正确的Python版本时,此特定示例可以正常工作:
$ python3.3
Python 3.3.0 (default, Sep 29 2012, 08:16:08)
[GCC 4.2.1 Compatible Apple Clang 3.1 (tags/Apple/clang-318.0.58)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> def outer():
... x = 1
... def inner():
... nonlocal x
... x = 2
... print("inner:", x)
... inner()
... print("outer:", x)
...
Names listed in a nonlocal statement must not collide with pre-existing bindings in the local scope.
非本地语句中列出的名称不得与本地范围内的现有绑定冲突。
https://docs.python.org/3/reference/simple_stmts.html#the-nonlocal-statement https://docs.python.org/3/reference/simple_stmts.html#the-nonlocal-statement
def outer(): x = 1 def inner(): nonlocal x y = 2 x = y print("inner: ", x) inner() print("outer: ", x)
>>> outer() inner: 2 outer: 2
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