How do I un-escape a backslash-escaped string in python?

Question

Suppose I have a string which is a backslash-escaped version of another string. Is there an easy way, in Python, to unescape the string? I could, for example, do:

>>> escaped_str = '"Hello,\\nworld!"'
>>> raw_str = eval(escaped_str)
>>> print raw_str
Hello,
world!
>>>

However that involves passing a (possibly untrusted) string to eval() which is a security risk. Is there a function in the standard lib which takes a string and produces a string with no security implications?

Answer 1

>>> print '"Hello,\\nworld!"'.decode('string_escape')
"Hello,
world!"

Answer 2

You can use ast.literal_eval which is safe:

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. (END)

Like this:

>>> import ast
>>> escaped_str = '"Hello,\\nworld!"'
>>> print ast.literal_eval(escaped_str)
Hello,
world!