or that your tone doesn’t fit the style
or the Python community, or whatever, I don’t think so. Look at the proposal to
change variable deletion time—that’s gotten a ton of pushback, and it’s
certainly not because nobody respects Guido or nobody likes him.
______
On Apr 10, 2020, at 12:46, Chamoun Saoma wrote:
>
> I have an idea to improve the python language through the creation of a new
> and very readable function.
> #
> def ranlen(x):
> #range of length of x
> return range(len(x))
> ###
tire new list
> before summing.
It sounds like you really are just looking for generator expressions, which
were added in Python 2.4 a couple decades ago. They have the same syntax as
list comprehensions without the square brackets, but they generate one element
at a time instead of generati
nswer to one of these—although unless that good
answer is performance, it seems like this should be a 5-line class in Python,
not a custom C class. (Keep in mind that defaultdict was added somewhere around
2.4 or 2.5, while __missing__ has only been there since somewhere around
2.7/3.3. I’ll bet it
a return value plus an OK or an Error, you
specify either an Ok(return value) or an Err(error value). Sure, technically
that’s the same amount of information, but the way it’s done, together with the
syntactic sugar provided by the language, makes a big difference, which I’ll
get to below.
>
CPython, a new class can have whatever
cross-implementation requirements we write into it. You can document that a
StringBuilder doesn’t retain all of its input strings, but is at minimum
roughly as efficient as making a list of strings and joining them anyway, and
every Python implementation will d
e presenting a
dynamic Spam* array terminated by a sentinel value), and iteration still works.___________
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e, as opposed to in collections or something else in
the Data Types chapter in the docs, but that’s true of most of functools, and
at least once people discover it (from a Python-list or StackOverflow question
or whatever) they’ll learn where it is and be able to use it easily, just like
the rest
s extra parameters in -- and the
> dataclass' __init__ won't accept extra arguments.
Can’t you just create InitVar attributes for the extra args you want to pass
through in that case?
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the connection between two key components in an
air traffic control system, then you probably do want to put in that effort. If
it’s an internal class that only gets constructed in one place, in a tool for
trolling each other with bad music in the office stereo that only you and three
colleag
effort—just make Y pass everything through, and the couple places you end up
needing to pass down one of those Pandas-y arguments you just do so, and it
works, and that’s fine.
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a file to resume the TLS session later on. Please tell me how
>> this is done if I'm wrong.
>
> Not a Python SSL expert, but have you tried pickling the session object?
>
> If that doesn't work, then I would say that adding pickle support
> (using the semantics y
it they could stay as competitors on PyPI forever, while if it turns out that
the extension hooks aren’t sufficient, someone could propose exactly what needs
to be changed to make the extension writable.
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any other dunder that is only implicitly called on builtin types?
Actually, IIRC, __getattr__ is itself another example. Python never calls
__getattr__, only __getattribute__. However, object.__getattribute__ (and
type.__getattribute__) calls __getattr__ on failure, the exact same way
dict.__
that, in idiomatic and readable
code (and in fact with variations—update, |, or ChainMap); why would I want to
be able to write the same thing in another way that’s conceptually backward,
probably less efficient, and doesn’t work in Python 3.8? If the issue is just
that you have those default va
either one of them…)
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way or not. And even if it does,
that hurdle of describing the syntax in a way that people won’t get confused
the way they do when they first learn the feature in C++ might be hard to
overcome. But it’s at least plausible that it could be readable and learnable
enough.
______
place where it gets complicated, but
there may be others I haven’t remembered. I can dig this up if you‘re
interested. Maybe it’s even worth cleaning up and posting to PyPI, or even
proposing for somewhere in the stdlib (collections or functools?).
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(And I like the
overall idea in this thread if someone can come up with good enough syntax.)
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Mapping…). Whether that counts as an argument for or against any version
of the various proposals in this thread, I’m not sure.
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On Apr 16, 2020, at 20:48, [email protected] wrote:
>
> In Javascript ES6 they don't have sets built like python so `{}` always
> refers to objects being constructed. It does indeed support implicit key:
> value pairs, so in ES6 `{ a: a, b: x, c: c }` is equivalent
d I think better, way.
> But implementing this change with the argument of making function calls less
> repetitive or verbose when having redundant named keywords and variables
> doesn't sell it to me.
>
> See, function calls would still suffer to be less redundant if we go with
> On Apr 17, 2020, at 01:58, Steven D'Aprano wrote:
>
> On Thu, Apr 16, 2020 at 09:21:05PM -0700, Andrew Barnert via Python-ideas
> wrote:
>
>> But I don’t see why that rules out the “bare colon” form that I and
>> someone else apparently both proposed
inly fluent) speakers
of a LTR-written language (as were the designers of Lisp, most of the C
committee, etc.). If Steve has a problem reading it, I think it’s probably just
him, but of course if I’m wrong I hope (and expect) others will chime in.
___
P
ing in that case.
I’m not sure how much that parallel means (or even what it would imply if it
did mean a lot). I think I’m still -0.5, and the fact that you can get the same
effect if you’re willing to use CPython frame hacks doesn’t make me either more
or less negative.
___
ot other uses of **unpacking, or
having a mode switch in the middle of call syntax, or anything else proposed so
far.)
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On Apr 17, 2020, at 13:12, David Mertz wrote:
>
> However, proposals for symbols in Python *do* pop
> up from time to time, so this would perhaps make such a thing harder if
> it ever becomes desired (which is unlikely, but possible).
Sure. It would also conflict with Nick Coghlan’
ort of get
the hang of doing, which is not usually what you’re aiming for with a language
feature.
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additional syntax with a different
meaning in just one specific context, calls, that’s not legal in the others.
Each special case like that makes the language’s syntax a little harder to
internalize, and it’s a good thing that Python has a lot fewer such special
cases than, say, C.
Worse, this
exception adds a small cost to
learning the language, but Python doesn’t have to be perfectly regular like
Lisp or Smalltalk, it just has to be a lot less irregular than C or Perl. Most
special cases aren’t special enough, but some are.
A subscription looks like a list display, but it’s not. Mi
On Apr 20, 2020, at 08:41, J. Pic wrote:
>
>
> Currently, list.append(x) mutates the list and returns None.
Yes, which is consistent with the vast majority of mutating methods in Python.
It would be pretty weird to make lst.append(x) return x, while lst.extend(xs)
still returns Non
On Apr 20, 2020, at 01:06, M.-A. Lemburg wrote:
>
> The current version already strikes me as way too complex.
> It's by far the most complex piece of grammar we have in Python:
>
> funcdef: 'def' NAME parameters ['->' test] ':' [TYPE_COMMEN
o be added as a flag on the builtin.
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On Apr 20, 2020, at 11:01, Christopher Barker wrote:
>
> The JSON - related example is a good one -- JSON maps well to "data" in
> Python, dicts and lists of numbers and strings. If you find yourself
> converting a bunch of variable names to/from JSON, you probably shoul
ould be a better design if you were doing Python from
scratch, but I think the established existence of zip_longest pushes us the
other way.
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On Apr 20, 2020, at 13:03, Eric V. Smith wrote:
>
> On 4/20/2020 3:39 PM, Andrew Barnert via Python-ideas wrote:
>>
>>
>> As I said, wanting to check does come up sometimes—I know I have written
>> this myself at least once, and I’d be a little surprised if
matter if you zip(y, x, strict=True) instead?
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ht
it’s a declarative format, it’s just that often it’s intended to be
understood as representing an object graph.
> In Python, you need to decide how you want to work with it, either as an
> object with attributes or a dict. But if you are getting it from JSON, it's a
> dict to begin
new
strict=True/zip_strict/zip_equal) is probably not a great tragedy.
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y even with `strict=True`"
out loud; maybe that's a mild argument for using a different qualifier like
`equal`, as in more-itertools?)
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marginal benefit. That’s why I think the whole
proposal is marginal. It’s almost never going to be a huge win—but it may be a
small win in so many places that it adds up to being worth it.
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On Apr 20, 2020, at 16:24, M.-A. Lemburg wrote:
>
> On 20.04.2020 19:43, Andrew Barnert via Python-ideas wrote:
>>> On Apr 20, 2020, at 01:06, M.-A. Lemburg wrote:
>>>
>>> The current version already strikes me as way too complex.
>>> It's by f
> On Apr 20, 2020, at 17:22, Steven D'Aprano wrote:
>
> On Mon, Apr 20, 2020 at 03:28:09PM -0700, Andrew Barnert via Python-ideas
> wrote:
>
>> Admittedly, such cases are almost surely not that common, but I
>> actually have some line-numbering code that did so
On Apr 21, 2020, at 01:27, M.-A. Lemburg wrote:
>
> On 21.04.2020 04:25, Andrew Barnert via Python-ideas wrote:
>>> On Apr 20, 2020, at 16:24, M.-A. Lemburg wrote:
>>>
>>> On 20.04.2020 19:43, Andrew Barnert via Python-ideas wrote:
>>>>>
On Apr 21, 2020, at 01:36, Serhiy Storchaka wrote:
>
> 20.04.20 23:33, Andrew Barnert via Python-ideas пише:
>> Should this print 1 or 2 or raise StopIteration or be a don’t-care?
>> Should it matter if you zip(y, x, strict=True) instead?
>
> It should print 2 in bot
th
it.
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proselytize for the next one.
If you can convince lots of people that they should care about the choice more
often and get them using the explicit functions, it’ll be a lot harder to argue
that everyone is happy with today’s behavior.
_______
Python-ideas mai
and counter start from zero by
> default. I would have asked you why you were counting your lines
> starting from zero instead of using `enumerate(xs, 1)` but I thought
> that was intentional.
You were right, counting from 0 was intentional. Just as it is almost
everywhere in Python. Th
> On Apr 21, 2020, at 16:02, Steven D'Aprano wrote:
>
> On Tue, Apr 21, 2020 at 12:25:06PM -0700, Andrew Barnert via Python-ideas
> wrote:
>>> On Apr 21, 2020, at 01:36, Serhiy Storchaka wrote:
>>> except ValueError: # assuming that’s the excepti
d by extend. And of course you’re adding extend_const. I don’t know if
that’s worth fixing separately, but if not it seems to me it’s probably worth
fixing in your patch.
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> On Apr 22, 2020, at 14:09, Steven D'Aprano wrote:
>
> On Wed, Apr 22, 2020 at 10:33:24AM -0700, Andrew Barnert via Python-ideas
> wrote:
>
>> If that is your long-term goal, I think you could do it in three steps.
>
> I think the first step is a PEP. This i
even
after you figure it out, it would hardly be any more obvious to other people
who need a noop function where to go digging for it than it was for you.
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ved that problem, and now everyone
can stop talking past each other.
(Although the couple of people who suggested wanting to _handle_ the error as a
normal case rather than treating it as a logic error to debug like your
examples still need to give use cases if they want anything different th
On Apr 25, 2020, at 09:40, Christopher Barker wrote:
>
> - The main exception to this may be when one of them is infinite, but how
> common is that, really? Remember that when zip was first created (py2) it was
> a list builder, not an iterator, and Python itself was much less
on. This includes the really trivial case where you know
what’s needed before you fork any threads that might need it (although for a
lot of those cases, in Python, it’s probably simpler to just use a module
global, but using an unsynchronized cache isn’t terrible for readability).
Of course it’s
On Apr 26, 2020, at 14:36, Daniel Moisset wrote:
>
> This idea is something I could have used many times. I agree with many people
> here that the strict=True API is at least "unusual" in Python. I was thinking
> of 2 different API approaches that could be used for t
On Apr 26, 2020, at 16:58, Steven D'Aprano wrote:
>
> On Sun, Apr 26, 2020 at 04:13:27PM -0700, Andrew Barnert via Python-ideas
> wrote:
>
>> But if we add methods on zip objects, and then we add a new skip()
>> method in 3.10, how does the backport work? It
not possible (and hence we may have done some work that we want to
> "roll-back" in some sense).
Agreed. But here’s a different way to look at it:
The Python iteration protocol hides the difference between different kinds of
iterables; every iterator is just a dumb next-only
is a lot
shorter, easier to understand, harder to get wrong, and more flexible (e.g., it
works unchanged with any number of iterables, while yours to had to rewritten
for any different number of iterables because it requires N! chunks of explicit
boilerplate).
Are there any examples where it lets yo
ABC: filter can _never_ preserve Sized but can _always_
preserves Reversible, etc.
This is clearly feasible—Swift does it, and C++ is trying to do it in their
next version, and Python already does it in a few special cases (as mentioned
earlier), just not in all (or even most) of the potent
by using numpy.
> I haven't found a real use-case for this yet, tho.
> SIMD is handled by numpy, which does a better job than you could ever hope
> for in plain python, and for SIMD you could use zip_longest with a suitable
> dummy instead. but... yeah, not really useful.
ok at proprietary code
> so I post about stuff in the hopes that the ppl who can will back this stuff
> up.
>
> (doesn't proprietary software make things so much harder? :/)
A little bit, but not nearly as much as you seem to be thinking. There are
zillions of lines of open so
re of a rationale than “let’s say you want to intermingle the
bits of two 16-bit integers into a 32-bit integer”. Sure, that’s something
that’s easy to do in some other languages (it’s the builtin $ operator in
INTERCAL) but very hard to do readably or efficiently in Python. If we added a
$ oper
or more powerful?
>
> the only one with equivalent semantics is the last one.
I won’t argue about whether two functions that give the exact same results in
every case but get there in different ways are “equivalent” or not, since one
is already good enough.
If you agree that there is obvi
one else is missing. To
the user of this module, this really should look like a variable, not a
function. The fact that we want to initialize it later shouldn’t change that.
Especially not in Python—other languages bend over backward to make you write
getters around every public attribute even
ind of the opposite of fun. :)
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On Apr 28, 2020, at 12:02, Alex Hall wrote:
>
> Some libraries implement a 'lazy object' which forwards all operations to a
> wrapped object, which gets lazily initialised once:
>
> https://github.com/ionelmc/python-lazy-object-proxy
> https://docs.djangoprojec
access the value is probably even less
acceptable when unnecessary.
So, I think it makes sense to leave it up to the user (but to explain the issue
in the docs). Or maybe we could add a threading.once (and asyncio.once?) as
well as functools.once?
___________
Pyt
ode before the splice point (or, for doubly-linked, after is fine
too). Another reason to use (Lisp/Haskell-style) linked lists is that they
automatically release nodes as you iterate unless you keep a reference to the
head, but that’s clumsy to do with P
olves half of those problems (as long
as “longest” is one of the options), but it makes others even worse. The
available strings aren’t even discoverable as part of the signature,
auto-complete won’t help at all, and the result is even longer and even more
deemphasizes the important thing.
__
le (and the tutorial?) could both just have a sentence
saying “Python doesn’t have a linked list type because there are so many useful
kinds of linked lists and they’re all easy to build but very different—see the
Linked Lists HOWTO for details.”
But if I wrote it, it would probably be 4x as long as a
ght the first time, rather than repeating the same mistake.
Is there anything about Python’s memory model guarantee that means it can’t
happen in Python? I don’t think there _is_ a memory model. In CPython, or any
GIL-based implementation, I _think_ it’s safe (the other thread can’t be
running at th
e
first one, it’ll be just as easy to figure out that zip_equal is what they’re
looking for from the second.
Of course it might be better to rewrite the whole thing to be more
novice-friendly and to describe what zip iterates at a higher level instead of
describing how its __next__ method oper
On Apr 29, 2020, at 22:50, Stephen J. Turnbull
wrote:
> Andrew Barnert via Python-ideas writes:
>
>>> Also -1 on the flag.
>
> Also -1 on the flag, for the same set of reasons.
>
> I have to dissent somewhat from one of the complaints, though:
>
>> auto
On May 1, 2020, at 08:08, Christopher Barker wrote:
>
> Also please keep in mind that the members of this list, and the python-dev
> list, are not representative of most Python users. Certainly not beginners
> but also many (most?) fairly active, but more "casual" use
exactly
what should be changed and where.
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On May 1, 2020, at 10:27, gbs--- via Python-ideas
wrote:
>
> In cases where it makes sense to do explicit type checking (with ABCs or
> whatever), I really detest the look of the isinstance() function.
>
> if isinstance(thing, Fruit) and not isinstance(thing, Apple):
>
ty libraries immediately, as long as
there’s an available backport (whether that’s more-iterools, or a trivial zip39
or whatever) that they can require; a flag can’t be used in libraries until
they’re able to require Python 3.9 (unless they want to use a backport that
monkey patches or shadows the bu
mplies that you were right
about the best way to get anything done.
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Messa
On May 1, 2020, at 16:32, Steven D'Aprano wrote:
>
> On Fri, May 01, 2020 at 12:28:02PM -0700, Andrew Barnert via Python-ideas
> wrote:
>>> On May 1, 2020, at 09:24, Christopher Barker wrote:
>>> Maybe it's too late for this, but I would love it
On May 1, 2020, at 15:35, Steven D'Aprano wrote:
>
> but if it is all functions, then I think you have no choice but to
> either live with it or shift languages, because the syntax for functions
> is too deeply baked into Python to change now.
Actually, I’m pretty sure Pytho
r PyPy-STM, or a future GIL-less Python?
>
> While I truly do appreciate your feedback on this idea, I’m really not clear
> on your line of reasoning here. What specifically do you propose would be the
> issue with the *Python* implementation? Are you proposing that under some
ount of stuff to learn in builtins just as much as another
function would. And so on. So it’s only worth doing for really special cases,
like open.
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eshedding issues (which you already raised),
not serious objections to considering them parallel. And I think all of the
other differences are either irrelevant, or obviously compelled by differences
between the languages (e.g., Python doesn’t need a rule for how it’s different
between the
a cache key. You
need a hashable sequence of the same values. And the way to spell that in
Python is tuple.
And that’s not a design flaw in Python, it’s a feature. (Shimmer is a floor wax
_and_ a dessert topping!) Sure, when you see a tuple, the default first guess
is that it’s an anonymous
em).
>> If it is set, the check for the type of self will be omitted, and you
>> can pass an arbitrary object as the first argument of the unbound method.
>
> Does this effect code written in Python? As I understand, in Python
> code, unbound methods are just plain old func
ated
textbooks. Which is pretty odd.
[4] Or even later, after giving the same spatial boundaries, then the same
temporal boundaries, then the math/logic definition, but I’m lumping those all
together as one sense because they’re coextensive if spacetime Is topological.
:)
___
On May 8, 2020, at 20:36, Dan Sommers <[email protected]>
wrote:
>
> On Fri, 8 May 2020 17:40:31 -0700
> Andrew Barnert via Python-ideas wrote:
>
>> So, the OP is right that (1,2,3)==[1,2,3] would sometimes be handy,
>> the opponents ar
> On May 9, 2020, at 04:30, Alex Hall wrote:
>
>> On Fri, May 8, 2020 at 11:22 PM Andrew Barnert via Python-ideas
>> wrote:
>
>> Trying to make it a flag (which will always be passed a constant value) is a
>> clever way to try to get the
imilar to a class with __next__, send, throw, and close
methods. But that doesn’t really change your point.
For a different angle on this: What If Python 3.10 changed things so that every
generator function actually did define a new class (maybe even accessible as a
member of the function)? What
ly
did turn out to be occasionally useful.)___________
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On May 9, 2020, at 12:38, Christopher Barker wrote:
>
> https://github.com/PythonCHB/islice-pep/blob/master/pep-xxx-islice.rst
I haven’t read the whole thing yet, but one thing immediately jumped out at me:
> and methods on containers, such as dict.keys return iterators in Python 3,
ight place for it. I have a similar
“lexicompare” in my toolbox, but it has extra options that YAGNI. Anyway, even
if I’m remembering right, you probably don’t need to dig up the more-itertools
PR because it’s easy enough to redo from scratch.)
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==y for x,y in zip_longest(self.it, other,
fillvalue=object()))
def __lt__(self, other):
for x, y in zip_longest(self.it, other, fillvalue=_Smallest()):
if x < y: return True
elif x < y: return False
return False
__
>
> > and methods on containers, such as dict.keys return iterators in Python 3,
>
> No they don’t. They return views—objects that are collections in their own
> right (in particular, they’re not one-shot; they can be iterated over and
> over) but just delegate to a
On May 9, 2020, at 17:35, Steve Jorgensen wrote:
>
> I believe the Python standard library should include a means of sanitizing a
> filesystem entry, and this should not be something requiring a 3rd party
> package.
>
> One of reasons I think this should be in the stand
worth it, and that any form of this proposal would make it even rarer,
but I could be wrong.
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27;, '6', '7', '8', '9']
You just picked an example where “resettable iterator” and “collection” would
do the same thing. Try the same test with list and it also passes, because list
is a collection. You can only distinguish the two cases by partially using a
acters in other error messages when they
come directly from the user’s input text. For example, if I try to 2+Spám(),
the error message will have á in the string.)
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ten or fixed manually, and
that’ll show you”, we can tell them “Use a proper editor in the future, but
meanwhile you can fix your existing script with `python -m defancier -f
script.py`“.
And a simple IDE or editor mode that doesn’t want to come up with something
better could run defanc
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