将字典的字符串表示转换为字典? [英] Convert a String representation of a Dictionary to a dictionary?

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问题描述

如何将 str 表示为 dict (如下列字符串)转换为 dict

How can I convert the str representation of a dict, such as the following string, into a dict?

s = "{'muffin' : 'lolz', 'foo' : 'kitty'}"

我不想使用 eval 。还有什么我可以使用的?

I prefer not to use eval. What else can I use?

这个的主要原因是我写的同事之一,将所有输入转换成字符串。我不会去修改他的课程,以处理这个问题。

The main reason for this, is one of my coworkers classes he wrote, converts all input into strings. I'm not in the mood to go and modify his classes, to deal with this issue.

推荐答案

从Python 2.6开始可以使用内置的 ast.literal_eval

Starting in Python 2.6 you can use the built-in ast.literal_eval:

>>> import ast
>>> ast.literal_eval("{'muffin' : 'lolz', 'foo' : 'kitty'}")
{'muffin': 'lolz', 'foo': 'kitty'}

这比使用 eval 更安全。正如其自己的文档所说:

This is safer than using eval. As its own docs say:


>>> help(ast.literal_eval)
Help on function literal_eval in module ast:

literal_eval(node_or_string)
    Safely evaluate an expression node or a string containing a Python
    expression.  The string or node provided may only consist of the following
    Python literal structures: strings, numbers, tuples, lists, dicts, booleans,
    and None.

例如:

>>> eval("shutil.rmtree('mongo')")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<string>", line 1, in <module>
  File "/opt/Python-2.6.1/lib/python2.6/shutil.py", line 208, in rmtree
    onerror(os.listdir, path, sys.exc_info())
  File "/opt/Python-2.6.1/lib/python2.6/shutil.py", line 206, in rmtree
    names = os.listdir(path)
OSError: [Errno 2] No such file or directory: 'mongo'
>>> ast.literal_eval("shutil.rmtree('mongo')")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/opt/Python-2.6.1/lib/python2.6/ast.py", line 68, in literal_eval
    return _convert(node_or_string)
  File "/opt/Python-2.6.1/lib/python2.6/ast.py", line 67, in _convert
    raise ValueError('malformed string')
ValueError: malformed string

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