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[Python-Dev] Internal representation of strings and Micropython

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On 06/06/2014 09:53, Hrvoje Niksic wrote:> On 06/04/2014 05:52 PM, Mark Lawrence wrote:>> On 04/06/2014 16:32, Steve Dower wrote:>>>>>> If copying into a separate list is a problem (memory-wise),>>> re.finditer('\\S+', string) also provides the same behaviour and>>> gives me the sliced string, so there's no need to index for anything.>>>>>>> Out of idle curiosity is there anything that stops MicroPython, or any>> other implementation for that matter, from providing views of a string>> rather than copying every time?  IIRC memoryviews in CPython rely on the>> buffer protocol at the C API level, so since strings don't support this>> protocol you can't take a memoryview of them.  Could this actually be>> implemented in the future, is the underlying C code just too>> complicated, or what?>>>> Memory view of Unicode strings is controversial for two reasons:>> 1. It exposes the internal representation of the string. If memoryviews> of strings were supported in Python 3, PEP 393 would not have been> possible (without breaking that feature).>> 2. Even if it were OK to expose the internal representation, it might> not be what the users expect. For example, memoryview("Hrvoje") would> return a view of a 6-byte buffer, while memoryview("Nikšić") would> return a view of a 12-byte UCS-2 buffer. The user of a memory view might> expect to get UCS-2 (or UCS-4, or even UTF-8) in all cases.>> An implementation that decided to export strings as memory views might> be forced to make a decision about internal representation of strings,> and then stick to it.>> The byte objects don't have these issues, which is why in Python 2.7> memoryview("foo") works just fine, as does memoryview(b"foo") in Python 3.>Thanks for the explanation :)-- My fellow Pythonistas, ask not what our language can do for you, ask what you can do for our language.Mark Lawrence---This email is free from viruses and malware because avast! Antivirus protection is active.http://www.avast.com

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