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

[Nathaniel Smith]

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