[Python-Dev] Adding bytes.frombuffer() constructor to PEP 467 (was: [Python-ideas] Adding bytes.frombuffer() constructor (original) (raw)

Nathaniel Smith njs at pobox.com
Wed Oct 12 01:03:37 EDT 2016

On Tue, Oct 11, 2016 at 9:08 PM, INADA Naoki <songofacandy at gmail.com> wrote:

From Python 3.4, bytearray is good solution for I/O buffer, thanks to #19087 [1]. Actually, asyncio uses bytearray as I/O buffer often.

Whoa what?! This is awesome, I had no idea that bytearray had O(1) deletes at the front. I literally reimplemented this myself on type of bytearray for some 3.5-only code recently because I assumed bytearray had the same asymptotics as list, and AFAICT this is totally undocumented. Shouldn't we write this down somewhere? Maybe here? -> https://docs.python.org/3/library/functions.html#bytearray

# when length=-1 (default), use until end of byteslike. bytes.frombuffer(byteslike, length=-1, offset=0)

This seems reasonable to me. Mostly I've dealt with the problem by writing functions like your read_line so that they return bytearray objects, since that's the only thing you can get out of a bytearray without double-copying. But returning bytes would feel a bit cleaner, and this would allow that.

-n

-- Nathaniel J. Smith -- https://vorpus.org

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