为什么此字符串不能与ast.literal_eval一起使用 [英] Why does this string not work with ast.literal_eval

问题描述

我收到了格式错误的字符串错误.

I get a malformed string error.

这是我的测试

>>> eval("'Hello:: '+'fdsfds'")
'Hello:: fdsfds'
>>> import ast
>>> ast.literal_eval("'Hello:: '+'fdsfds'")
Traceback (most recent call last):
  File "<pyshell#4>", line 1, in <module>
    ast.literal_eval("'Hello:: '+'fdsfds'")
  File "C:\Python27\lib\ast.py", line 80, in literal_eval
    return _convert(node_or_string)
  File "C:\Python27\lib\ast.py", line 79, in _convert
    raise ValueError('malformed string')
ValueError: malformed string

推荐答案

来自ast.literal_eval docs :

提供的字符串或节点只能由以下Python文字结构组成:字符串，数字，元组，列表，字典，布尔值和无.

The string or node provided may only consist of the following Python literal structures: strings, numbers, tuples, lists, dicts, booleans, and None.

使用+的串联不包括在其中:它不是文字表达式，而是对str.__add__的调用.与1+1或"hello".upper()无法正常工作的原因相同.

Concatenation using + isn't included within that: it's not a literal expression, it's a call to str.__add__. It's the same reason 1+1 or "hello".upper() wouldn't work.

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