How to unencapsulate string for another string?

Question

I'd like to unencapsulate a string (in Python) from another string.

For example, from:

>>> string1
"u'abcde'"

I'd like to get:

>>> string2
'abcde'

`string1.split("'")[1]` also works. – martineau Feb 06 '15 at 14:16 — martineau, Feb 06 '15 at 14:16

Avinash Raj · Accepted Answer · 2015-02-06T12:19:52.607

1

Seems like you want the function eval

>>> stri = "u'abcde'"
>>> eval(stri)
'abcde'

>>> help(eval)
Help on built-in function eval in module builtins:

eval(...)
    eval(source[, globals[, locals]]) -> value

    Evaluate the source in the context of globals and locals.
    The source may be a string representing a Python expression
    or a code object as returned by compile().
    The globals must be a dictionary and locals can be any mapping,
    defaulting to the current globals and locals.
    If only globals is given, locals defaults to it.

As per the below comments, you need to use ast.literal_eval function instead of in-built eval function because eval will evaluate arbitrary (and potentially dangerous) code, whereas ast.literal_eval will only evaluate Python literals.

>>> import ast
>>> stri = "u'abcde'"
>>> ast.literal_eval(stri)
'abcde'

edited Feb 06 '15 at 12:19

answered Feb 06 '15 at 12:11

Avinash Raj

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for safety you should use `ast.literal_eval` instead of `eval` – jamylak Feb 06 '15 at 12:13
@jamylak may i know why? – Avinash Raj Feb 06 '15 at 12:15
Yeah, to elaborate, you could inject whatever code you want inside `eval` to delete all your files and other things. – jamylak Feb 06 '15 at 12:16
2

@AvinashRaj because `eval` will evaluate arbitrary (and potentially dangerous) code, whereas `ast.literal_eval` will only evaluate Python literals. See [the docs](https://docs.python.org/2/library/ast.html#ast.literal_eval) and e.g. http://stackoverflow.com/q/1832940/3001761. – jonrsharpe Feb 06 '15 at 12:17
Thanks `^.*\b(jon|jamy)` – Avinash Raj Feb 06 '15 at 12:23

How to unencapsulate string for another string?

1 Answers1