more on unescaping escapes

[MRAB]

bvdp wrote:
> 
> So, we think something is working and send of a bug fix to our client :)
> 
> I'm not sure I understand this at all and wonder if there is bug?
> 
>  >>> a="c:\\Program\x20Files\\test"
>  >>> a
> 'c:\\Program Files\\test'
> 
> so far, so good.
> 
>  >>> a.decode("string-escape")
> 'c:\\Program Files\test'
> 
> Umm, not so good? The \\ before the P is okay, but the \\t is change to \t
> 
Decoding changes "\\x20" to "\x20", which is the same as " ", a space.

Decoding changes "\\t" to "\t", which is a tab.

Decoding _doesn't_ change "\\P" to "\P" because that's not a valid
escape sequence.

> and
> 
>  >>> print a.decode("string-escape")
> c:\Program Files        est
> 
> Now, decode() converted the \\t to a \t and print expanded the \t to a tab.
> 
\t is already a tab.

> I would have thought that the \\t would have the same result as the \\P ???
> 
> Obviously my brain is missing something (hopefully obvious).
> 
Before storing the string (writing it to the file), encode it and then
replace " " with "\\x20":

     C:\Program Files\test

becomes:

     C:\Program Files\test

and then:

     C:\\Program\x20Files\\test

After fetching the string (reading it from the file), decode it:

     C:\\Program\x20Files\\test

becomes:

     C:\Program Files\test