Re: [Python-ideas] incremental hashing in __hash__

On 5 January 2017 at 00:31, Steven D'Aprano wrote: > This is a good point. Until now, I've been assuming that > hash.from_iterable should consider order. But frozenset shows us that > sometimes the hash should *not* consider order. > > This hints that perhaps the hash.from_iterable() should have i

Re: [Python-ideas] incremental hashing in __hash__

But, I think that the problem with adding `__hash__` to collections.abc.Iterable is that not all iterables are immutable -- And if they aren't immutable, then allowing them to be hashed is likely to be a pretty bad idea... I'm still having a hard time being convinced that this is very much of an o

Re: [Python-ideas] incremental hashing in __hash__

On 28.12.2016 04:13, [email protected] wrote: > Suppose you have implemented an immutable Position type to represent > the state of a game played on an MxN board, where the board size can > grow quite large. > ... > > According to > https://docs.python.org/3/reference/datamodel.html#object.__ha

Re: [Python-ideas] incremental hashing in __hash__

On Thu, Jan 5, 2017 at 4:00 AM Matt Gilson wrote: > But, I think that the problem with adding `__hash__` to > collections.abc.Iterable is that not all iterables are immutable -- And if > they aren't immutable, then allowing them to be hashed is likely to be a > pretty bad idea... > Good point.

Re: [Python-ideas] incremental hashing in __hash__

The point is that the OP doesn't want to write his own hash function, but wants Python to provide a standard way of hashing an iterable. Today, the standard way is to convert to tuple and call hash on that. That may not be efficient. FWIW from a style perspective, I agree with OP. On Thu, Jan 5,

Re: [Python-ideas] incremental hashing in __hash__

On Thu, Jan 5, 2017, at 04:00, Matt Gilson wrote: > But, I think that the problem with adding `__hash__` to > collections.abc.Iterable is that not all iterables are immutable -- And > if > they aren't immutable, then allowing them to be hashed is likely to be a > pretty bad idea... Why? This shoul

[Python-ideas] PEP 540: Add a new UTF-8 mode

Hi, Nick Coghlan asked me to review his PEP 538 "Coercing the legacy C locale to C.UTF-8": https://www.python.org/dev/peps/pep-0538/ Nick wants to change the default behaviour. I'm not sure that I'm brave enough to follow this direction, so I proposed my old "-X utf8" command line idea as a new P

Re: [Python-ideas] incremental hashing in __hash__

On 5 January 2017 at 13:28, Neil Girdhar wrote: > The point is that the OP doesn't want to write his own hash function, but > wants Python to provide a standard way of hashing an iterable. Today, the > standard way is to convert to tuple and call hash on that. That may not be > efficient. FWIW f

Re: [Python-ideas] PEP 540: Add a new UTF-8 mode

> https://www.python.org/dev/peps/pep-0540/ I read the PEP 538, PEP 540, and issues related to switching to UTF-8. At least, I can say one thing: people have different points of view :-) To understand why people disagree, I tried to categorize the different point of views and Python expectations:

Re: [Python-ideas] PEP 540: Add a new UTF-8 mode

2017-01-05 17:50 GMT+01:00 Victor Stinner : > In its current shame, my PEP 540 leaves Python default unchanged, but > adds two modes: UTF-8 and UTF-8 strict. The UTF-8 mode is more or less > the UNIX mode generalized for all inputs and outputs: mojibake is a > feature, just pass bytes unchanged. Th

Re: [Python-ideas] incremental hashing in __hash__

I agree with Paul -- I'm not convinced that this is common enough or that the benefits are big enough to warrant something builtin. However, I did decide to dust off some of my old skills and I threw together a simple gist to see how hard it would be to create something using Cython based on the C

Re: [Python-ideas] PEP 540: Add a new UTF-8 mode

Hi! On Thu, Jan 05, 2017 at 04:38:22PM +0100, Victor Stinner wrote: > Always use UTF-8 > > > Python already always use the UTF-8 encoding on Mac OS X, Android and Windows. > Since UTF-8 became the defacto encoding, it makes sense to always use it on > all > platforms with any

Re: [Python-ideas] incremental hashing in __hash__

On Thu, Jan 5, 2017 at 10:58 AM Paul Moore wrote: > On 5 January 2017 at 13:28, Neil Girdhar wrote: > > The point is that the OP doesn't want to write his own hash function, but > > wants Python to provide a standard way of hashing an iterable. Today, > the > > standard way is to convert to tup

Re: [Python-ideas] PEP 540: Add a new UTF-8 mode

On Thu, Jan 05, 2017 at 04:38:22PM +0100, Victor Stinner wrote: [...] > Python 3 promotes Unicode everywhere including filenames. A solution to > support filenames not decodable from the locale encoding was found: the > ``surrogateescape`` error handler (`PEP 393 >

Re: [Python-ideas] PEP 540: Add a new UTF-8 mode

>> Always use UTF-8 >> >> >> Python already always use the UTF-8 encoding on Mac OS X, Android and >> Windows. >> Since UTF-8 became the defacto encoding, it makes sense to always use it on >> all >> platforms with any locale. > >Please don't! I use different locales and enco

Re: [Python-ideas] PEP 540: Add a new UTF-8 mode

2017-01-06 0:35 GMT+01:00 Steven D'Aprano : >> Python 3 promotes Unicode everywhere including filenames. A solution to >> support filenames not decodable from the locale encoding was found: the >> ``surrogateescape`` error handler (`PEP 393 >> `_), store u

Re: [Python-ideas] PEP 540: Add a new UTF-8 mode

Ok, I modified my PEP: the POSIX locale now enables the UTF-8 mode. 2017-01-05 18:10 GMT+01:00 Victor Stinner : > A common request is that "Python just works" without having to pass a > command line option or set an environment variable. Maybe the default > behaviour should be left unchanged, but

Re: [Python-ideas] PEP 540: Add a new UTF-8 mode

2017-01-06 2:15 GMT+01:00 INADA Naoki : >>> Always use UTF-8 (...) >>Please don't! (...) > > For stdio (including console), PYTHONIOENCODING can be used for > supporting legacy system. > e.g. `export PYTHONIOENCODING=$(locale charmap)` The problem with ignoring the locale by default and forcin

Re: [Python-ideas] incremental hashing in __hash__

Paul Moore writes: > The debate here regarding tuple/frozenset indicates that there may not > be a "standard way" of hashing an iterable (should order matter?). If part of the data structure, yes, if an implementation accident, no. > Although I agree that assuming order matters is a reasonabl

Re: [Python-ideas] PEP 540: Add a new UTF-8 mode

Oleg Broytman writes: > On Thu, Jan 05, 2017 at 04:38:22PM +0100, Victor Stinner > wrote: > > Since UTF-8 became the defacto encoding, it makes sense to always > > use it on all platforms with any locale. > >Please don't! I've quoted Victor out of context, and his other posts make m

Re: [Python-ideas] PEP 540: Add a new UTF-8 mode

Victor Stinner writes: > Python 3.6 is not exactly in the first or the later category: "it > depends". > > To read data from the operating system, Python 3.6 behaves in "UNIX > mode": os.listdir() *does* return invalid filenames, it uses a funny > encoding using surrogates. > > To write

Re: [Python-ideas] PEP 540: Add a new UTF-8 mode

2017-01-06 3:10 GMT+01:00 Stephen J. Turnbull : > I've quoted Victor out of context, and his other posts make me very > doubtful that he considers this a serious alternative. That said, I'm > +1 on "don't!" The "always ignore locale and force UTF-8" option has supporters. For example, Nick Coghla

Re: [Python-ideas] PEP 540: Add a new UTF-8 mode

2017-01-06 3:10 GMT+01:00 Stephen J. Turnbull : > The point of this, I suppose, is that piping to xargs works by > default. Please read the second version (latest) version of my PEP 540 which contains a new "Use Cases" section which helps to define issues and the behaviour of the different modes.

Re: [Python-ideas] PEP 540: Add a new UTF-8 mode

On 6 January 2017 at 12:37, Victor Stinner wrote: > 2017-01-06 3:10 GMT+01:00 Stephen J. Turnbull > : >> I've quoted Victor out of context, and his other posts make me very >> doubtful that he considers this a serious alternative. That said, I'm >> +1 on "don't!" > > The "always ignore locale and

Re: [Python-ideas] incremental hashing in __hash__

On Thu, Jan 5, 2017 at 9:10 PM Stephen J. Turnbull < [email protected]> wrote: > Paul Moore writes: > > > The debate here regarding tuple/frozenset indicates that there may not > > be a "standard way" of hashing an iterable (should order matter?). > > If part of the data struct

Re: [Python-ideas] PEP 540: Add a new UTF-8 mode

On Fri, Jan 06, 2017 at 02:54:49AM +0100, Victor Stinner wrote: > Let's say that you have the filename b'nonascii\xff': it's decoded as > 'nonascii\xdcff' by the UTF-8 mode. How do GUIs handle such filename? > (I don't know the answer, it's a real question ;-)) I ran this in Python 2.7 to create