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Re: Why is array.array('u') deprecated?

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From Peter Otten <__peter__@web.de>
Subject Re: Why is array.array('u') deprecated?
Date Fri, 08 May 2015 15:11:35 +0200
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jonathan.slenders@gmail.com wrote:

>> Can you expand a bit on how array("u") helps here? Are the matches in the
>> gigabyte range?
> 
> I have a string of unicode characters, e.g.:
> 
> data = array.array('u', u'x' * 1000000000)
> 
> Then I need to change some data in the middle of this string, for
> instance:
> 
> data[500000] = 'y'
> 
> Then I want to use re to search in this text:
> 
> re.search('y', data)
> 
> This has to be fast. I really don't want to split and concatenate strings.
> Re should be able to process it and the expressions can be much more
> complex than this. (I think it should be anything that implements the
> buffer protocol).
> 
> So, this works perfectly fine and fast. But it scares me that it's
> deprecated and Python 4 will not support it anymore.

Hm, this doesn't even work with Python 3:

>>> data = array.array("u", u"x"*1000)
>>> data[100] = "y"
>>> re.search("y", data)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python3.4/re.py", line 166, in search
    return _compile(pattern, flags).search(string)
TypeError: can't use a string pattern on a bytes-like object

You can search for bytes

>>> re.search(b"y", data)
<_sre.SRE_Match object; span=(400, 401), match=b'y'>
>>> data[101] = "z"
>>> re.search(b"y", data)
<_sre.SRE_Match object; span=(400, 401), match=b'y'>
>>> re.search(b"yz", data)
>>> re.search(b"y\0\0\0z", data)
<_sre.SRE_Match object; span=(400, 405), match=b'y\x00\x00\x00z'>

but if that is good enough you can use a bytearray in the first place.

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Thread

Why is array.array('u') deprecated? jonathan.slenders@gmail.com - 2015-05-08 02:14 -0700
  Re: Why is array.array('u') deprecated? wxjmfauth@gmail.com - 2015-05-08 02:37 -0700
  Re: Why is array.array('u') deprecated? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-05-08 20:29 +1000
    Re: Why is array.array('u') deprecated? jonathan.slenders@gmail.com - 2015-05-08 04:05 -0700
      Re: Why is array.array('u') deprecated? Peter Otten <__peter__@web.de> - 2015-05-08 13:35 +0200
        Re: Why is array.array('u') deprecated? jonathan.slenders@gmail.com - 2015-05-08 05:12 -0700
          Re: Why is array.array('u') deprecated? Peter Otten <__peter__@web.de> - 2015-05-08 15:11 +0200
            Re: Why is array.array('u') deprecated? jonathan.slenders@gmail.com - 2015-05-08 07:40 -0700
              Re: Why is array.array('u') deprecated? Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-05-11 08:03 +0100

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