[Python-Dev] Python 3.x and bytes

Antoine Pitrou solipsis at pitrou.net
Thu May 19 12:37:27 CEST 2011

On Thu, 19 May 2011 17:49:47 +1000
Nick Coghlan <ncoghlan at gmail.com> wrote:
> It's a mental model problem. People try to think of bytes as
> equivalent to 2.x str and that's just wrong, wrong, wrong. It's far
> closer to array.array('c'). Strings are basically *unique* in
> returning a length 1 instance of themselves for indexing operations.
> For every other sequence type, including tuples, lists and arrays,
> slicing returns a new instance of the same type, while indexing will
> typically return something different.
> Now, we definitely didn't *help* matters by keeping so many of the
> default behaviours of bytes() and bytearray() coupled to ASCII-encoded
> text, but that was a matter of practicality beating purity: there
> really *are* a lot of wire protocols out there that are ASCII based.

I think "practicality beating purity" should have been extended to
__getitem__ as well. I have almost never had a use for treating a
bytestring as a sequence of integers, while treating a bytestring as a
sequence of one-byte strings is *very* common.

(and, as you say, if you want a sequence of integers you can already
use array.array() which gives you more flexibility as to the width and
signedness of integers)



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