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Groups > comp.lang.python > #101751
| From | Wolfgang Maier <wolfgang.maier@biologie.uni-freiburg.de> |
|---|---|
| Newsgroups | comp.lang.python |
| Subject | Re: Powerful perl paradigm I don't find in python |
| Date | 2016-01-15 14:20 +0100 |
| Message-ID | <mailman.11.1452864029.15297.python-list@python.org> (permalink) |
| References | <n7adse$k6$1@dont-email.me> <n7af0o$kfr$1@ger.gmane.org> <mailman.5.1452854573.15297.python-list@python.org> <n7ajo0$k6v$1@dont-email.me> |
On 15.01.2016 12:04, Charles T. Smith wrote:
> On Fri, 15 Jan 2016 11:42:24 +0100, Wolfgang Maier wrote:
>
>> On 15.01.2016 10:43, Peter Otten wrote:
>>> Charles T. Smith wrote:
>>>
>>>> while ($str != $tail) {
>>>> $str ~= s/^(head-pattern)//;
>>>> use ($1);
>>>> }
>>>
> ....
>>
>> things = []
>> while some_str != tail:
>> m = re.match(pattern_str, some_str)
>> things.append(some_str[:m.end()])
>> some_str = some_str[m.end():]
>>
>> # do something with things
>
>
> Okay, I guess it's not a lot more work to use the end() method to manually
> cut out the found portion.
>
> What the original snippet does is parse *and consume* a string - actually,
> to avoid maintaining a cursor traverse the string. The perl feature is that
> substitute allows the found pattern to be replaced, but retains the group
> after the expression is complete.
>
> The end() method is actually such a cursor, but already set up for you
> by the class, and then the slicing considerably simplifies its use.
>
I see. If consuming the string is not essential for you, but just a
handy trick to avoid the cursor, you may prefer this (most likely
faster) solution:
pattern = pattern_str.compile()
try:
matches = pattern.findall(some_str, endpos=some_str.index(tail))
except ValueError:
# do something if tail is not found
pass
Best,
Wolfgang
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Powerful perl paradigm I don't find in python "Charles T. Smith" <cts.private.yahoo@gmail.com> - 2016-01-15 09:24 +0000
Re: Powerful perl paradigm I don't find in python Peter Otten <__peter__@web.de> - 2016-01-15 10:43 +0100
Re: Powerful perl paradigm I don't find in python Michael Vilain <vilain@NOspamcop.net> - 2016-01-15 02:20 -0800
Re: Powerful perl paradigm I don't find in python Wolfgang Maier <wolfgang.maier@biologie.uni-freiburg.de> - 2016-01-15 11:42 +0100
Re: Powerful perl paradigm I don't find in python "Charles T. Smith" <cts.private.yahoo@gmail.com> - 2016-01-15 11:04 +0000
Re: Powerful perl paradigm I don't find in python "Charles T. Smith" <cts.private.yahoo@gmail.com> - 2016-01-15 11:06 +0000
Re: Powerful perl paradigm I don't find in python Wolfgang Maier <wolfgang.maier@biologie.uni-freiburg.de> - 2016-01-15 14:20 +0100
Re: Powerful perl paradigm I don't find in python "Charles T. Smith" <cts.private.yahoo@gmail.com> - 2016-01-18 13:05 +0000
Re: Powerful perl paradigm I don't find in python Wolfgang Maier <wolfgang.maier@biologie.uni-freiburg.de> - 2016-01-18 14:33 +0100
Re: Powerful perl paradigm I don't find in python Peter Otten <__peter__@web.de> - 2016-01-15 14:34 +0100
Re: Powerful perl paradigm I don't find in python Ulli Horlacher <framstag@rus.uni-stuttgart.de> - 2016-01-15 13:51 +0000
Re: Powerful perl paradigm I don't find in python me <self@example.org> - 2016-01-15 15:20 +0000
Re: Powerful perl paradigm I don't find in python Nathan Hilterbrand <nhilterbrand@gmail.com> - 2016-01-15 11:54 -0500
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