On 01/19/2015 09:01 AM, Eric V. Smith wrote:

I'd return a new copy (or, not implement it at all and let the default machinery call __mod__, and do the assignment). That's the least surprising to me, since the goal is to be compatible with 2.7's str %-formatting.

That certainly feels like the winning argument. :) -- ~Ethan~

Hello, On Mon, 19 Jan 2015 14:03:20 -0800 Guido van Rossum wrote:

On Mon, Jan 19, 2015 at 11:43 AM, Paul Sokolovsky wrote:

...

[...] So, suppose there's a requirement to support inplace operations (methods) on bytearray, what would be Pythonic way to implement it?

Something like:

b.lower_inplace() b.lower_i()

, or maybe

import bytearray_ops bytearray_ops.lower(b)

?

Please don't go there. The use cases are too rare.

recv_into() an HTTP request and .lower() it inplace to ease parsing? But I mostly raise that with MicroPython hat on, there it may be not necessarily superfluous. But then, having a separate module for such operations doesn't seem too bad, except that it would be retrograde action after "string" module deprecation in favor of methods. Anyway, I targetted that question for python-ideas on some easy day, and just took a quick chance here seeing someone else talking about inplace bytearray operations ;-).

-- --Guido van Rossum (python.org/~guido)

-- Best regards, Paul mailto:pmiscml@gmail.com

Hello, On Tue, 20 Jan 2015 18:15:02 +1300 Greg Ewing wrote:

Guido van Rossum wrote:

...

On Mon, Jan 19, 2015 at 11:43 AM, Paul Sokolovsky mailto:pmiscml@gmail.com> wrote:

b.lower_inplace() b.lower_i()

Please don't go there. The use cases are too rare.

And if you have such a use case, it's not too hard to do

b[:] = b.lower()

The point of inplace operations (memoryview's, other stuff already in Python) is to avoid unneeded memory allocation and copying. For 1Tb bytearray with 1Tb of RAM, it will be very hard to do. (Ditto for 100K bytearray with 150K RAM.) -- Best regards, Paul mailto:pmiscml@gmail.com

On Tue, Jan 20, 2015 at 11:48:10AM +0200, Paul Sokolovsky wrote:

Hello,

On Tue, 20 Jan 2015 18:15:02 +1300 Greg Ewing wrote:

...

Guido van Rossum wrote:

...

On Mon, Jan 19, 2015 at 11:43 AM, Paul Sokolovsky mailto:pmiscml@gmail.com> wrote:

b.lower_inplace() b.lower_i()

Please don't go there. The use cases are too rare.

And if you have such a use case, it's not too hard to do

b[:] = b.lower()

The point of inplace operations (memoryview's, other stuff already in Python) is to avoid unneeded memory allocation and copying. For 1Tb bytearray with 1Tb of RAM, it will be very hard to do. (Ditto for 100K bytearray with 150K RAM.)

You can just loop through the bytearray and assign elements. I use something along the lines of this for PyParallel where I'm operating on bytearrays that are backed by underlying socket buffers, where I don't want to do any memory allocations/reallocations: def toupper_bytes(data): assert isinstance(data, bytearray) a = ord('a') z = ord('z') for i in range(0, len(data)): c = data[i] if c >= a and c <= z: data[i] = c - 32 Low overhead, mostly stays within the same ceval frame. Should be a walk in the park for PyPy, Cython or Numba to optimize, too. Trent.