unescape escapes in strings

[MRAB]

bvdp wrote:
> MRAB wrote:
>> bvdp wrote:
>>>
>>> When reading lines of data from a file in the from (no quotes!)
>>>
>>>     foo\x20bar
>>>
>>> and I assign to a variable in a line line like:
>>>
>>>  f = file('infile', 'r')
>>>  for a in f:
>>>     print a
>>>
>>> the string is read in as string with the literal characters 'f', 'o' 
>>> ... 'x' , '2' ...
>>>
>>> as compared to an assignment like:
>>>
>>>  a="foo\x20bar"
>>>
>>> which is identical to
>>>
>>> a="foo bar"
>>>
>>> Okay, so far ... I think this is what I want since my program is 
>>> using space characters as delimiters and I'm trying to use the \x20 
>>> notation to avoid splitting.
>>>
>>> But, now the problem. When I finally assign the string with the \x20 
>>> to a variable the literals are still there. And here I really want 
>>> them all nicely converted to the desired values.
>>>
>>> So, the question is: is there an "unescape()" for strings so that 
>>> "foo\x20bar" is converted to "foo bar"????
>>>
>>  >>> a = r"foo\x20bar"
>>  >>> print a
>> foo\x20bar
>>  >>> a = a.decode("string-escape")
>>  >>> print a
>> foo bar
>>
> 
> Thanks ... I think in my original testing I tried decode() but it didn't 
> work. Testing more ...
> 
>  the file has 2 lines:
>   foo bar
>   foo\x20bar
> 
> and the program to read is:
> f=file('in', 'r')
> for a in f:
>     a = a.strip()
>     a=a.decode()

You didn't specify what kind of decoding you want!

>     print list(a)
> 
> I get:
> 
> python read.py
> []
> [u'f', u'o', u'o', u' ', u'b', u'a', u'r']
> [u'f', u'o', u'o', u'\\', u'x', u'2', u'0', u'b', u'a', u'r']
> 
> So, the \x20 is still literal.
> 
> Any other ideas??? I suppose I could write a re expression ... but 
> surely that is not needed???
>