[Tutor] RE module is working ?

[Karim]

Hello,

Any news on this topic?O:-)

Regards
Karim

On 02/02/2011 08:21 PM, Karim wrote:
>
> Hello,
>
> I am trying to subsitute a '""' pattern in '\"\"' namely escape 2 
> consecutives double quotes:
>
>     * *In Python interpreter:*
>
> $ python
> Python 2.7.1rc1 (r271rc1:86455, Nov 16 2010, 21:53:40)
> [GCC 4.4.3] on linux2
> Type "help", "copyright", "credits" or "license" for more information.
> >>> expression = *' "" '*
> >>> re.subn(*r'([^\\])?"', r'\1\\"', expression*)
> Traceback (most recent call last):
>   File "<stdin>", line 1, in <module>
>   File "/home/karim/build/python/install/lib/python2.7/re.py", line 
> 162, in subn
>     return _compile(pattern, flags).subn(repl, string, count)
>   File "/home/karim/build/python/install/lib/python2.7/re.py", line 
> 278, in filter
>     return sre_parse.expand_template(template, match)
>   File "/home/karim/build/python/install/lib/python2.7/sre_parse.py", 
> line 787, in expand_template
>     raise error, "unmatched group"
> sre_constants.error: unmatched group
>
> But if I remove '?' I get the following:
>
> >>> re.subn(r'([^\\])"', r'\1\\"', expression)
> (' \\"" ', 1)
>
> Only one substitution..._But this is not the same REGEX._ And the 
> count=2 does nothing. By default all occurrence shoul be substituted.
>
>     * *On linux using my good old sed command, it is working with my
>       '?' (0-1 match):*
>
> *$* echo *' "" '* | sed *'s/\([^\\]\)\?"/\1\\"/g*'*
>  \"\"
>
> *Indeed what's the matter with RE module!?*
>
> *Any idea will be welcome!
>
> Regards
> Karim*
> *
>
>
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