How to decipher :re.split(r"(\(\([^)]+\)\))" in the example

Fri Jul 11 11:18:09 EDT 2014

----- Original Message -----
> From: Steven D'Aprano <steve at pearwood.info>
> To: python-list at python.org
> Cc: 
> Sent: Friday, July 11, 2014 11:04 AM
> Subject: Re: How to decipher :re.split(r"(\(\([^)]+\)\))" in the example
>> On 2014年7月10日 23:33:27 -0400, Roy Smith wrote:
>>> In article <mailman.11747.1405046292.18130.python-list at python.org>,
>>   Tim Chase <python.list at tim.thechases.com> wrote:
>>>>> On 2014年07月10日 22:18, Roy Smith wrote:
>>> > > Outside this are \( and \): these are literal opening 
> and closing
>>> > > bracket characters. So:
>>> > > 
>>> > >    \(\([^)]+\)\)
>>> >
>>> > although, even better would be to use to utterly awesome
>>> >> re.VERBOSE
>>> > flag, and write it as:
>>> > 
>>> >      \({2} [^)]+ \){2}
>>>>>> Or heck, use a multi-line verbose expression and comment it for
>>> clarity:
>>>>>>   r = re.compile(r"""
>>>     (            # begin a capture group
>>>       \({2}      # two literal "(" characters [^)]+  
>     # one or more
>>>       non-close-paren characters \){2}      # two literal 
> ")"
>>>       characters
>>>     )            # close the capture group """, 
> re.VERBOSE)
>>>>>> -tkc
>>>> Ugh.  That reminds me of the classic commenting anti-pattern:
>> The sort of dead-simple commenting shown below is not just harmless but 
> can be *critically important* for beginners, who otherwise may not know 
> what "l = []" means.
>>> l = []                  # create an empty list 
>> for i in range(10):    # iterate over the first 10 integers
>>     l.append(i)        # append each one to the list
>
Anything better than this hideous type of commenting: (?#...), e.g
>>> re.match("(19|20)[0-9]{2}(?#year)-[0-9]{2}(?#month)", "2010-12")
Same thing for the 'limsux' modifiers, although *maybe* they can be useful.