Re: [Python-Dev] What's the status of PEP 505: None-aware operators?

Eric Fahlgren wrote: ​I think you're missing something here, since it seems clear to me that indeed the arguments are evaluated prior to the function call.​ I think the OP may be confusing "evaluating the function" with "calling the function". If the function being called is determined by some

Re: [Python-Dev] Using async/await in place of yield expression

Guido van Rossum wrote: The source for sleep() isn't very helpful -- e.g. @coroutine is mostly a backwards compatibility thing. So how are you supposed to write that *without* using @coroutine? -- Greg ___ Python-Dev mailing list Python-Dev@python.o

Re: [Python-Dev] Second post: PEP 557, Data Classes

Chris Angelico wrote: I'm not sure there's any distinction between a "point" and a "vector from the origin to a point". They transform differently. For example, translation affects a point, but makes no difference to a vector. There are two ways of dealing with that. One is to use vectors to r

Re: [Python-Dev] Second post: PEP 557, Data Classes

Nick Coghlan wrote: Perhaps the check could be: (type(lhs) == type(rhs) or fields(lhs) == fields(rhs)) and all (individual fields match) I think the types should *always* have to match, or at least one should be a subclass of the other. Consider: @dataclass class Point3d: x: float y

Re: [Python-Dev] Tricky way of of creating a generator via a comprehension expression

Serhiy Storchaka wrote: Ivan explained that this function should be rough equivalent to def f(): t = [(yield i) for i in range(3)] return (x for x in t) This is a *rough* equivalent. There are differences in details. The details would seem to be overwhelmingly important, tho

Re: [Python-Dev] Tricky way of of creating a generator via a comprehension expression

Nick Coghlan wrote: def example(): comp1 = yield from [(yield x) for x in ('1st', '2nd')] comp2 = yield from [(yield x) for x in ('3rd', '4th')] return comp1, comp2 If the implicit "yield from" idea seems too magical, then the other direction we could go is to make

Re: [Python-Dev] Tricky way of of creating a generator via a comprehension expression

Guido van Rossum wrote: the extra scope is now part of the language definition. It can't be removed as a "bug fix". Does anyone actually rely on the scope-ness of comprehensions in any way other than the fact that it prevents local variable leakage? If not, probably nobody would notice if it w

Re: [Python-Dev] Tricky way of of creating a generator via a comprehension expression

Guido van Rossum wrote: The debugger does stop at each iteration. It does see a local named ".0" I suppose there currently is no way for the debugger to map the variable names to what they are named in the source, right? If the hidden local were named "a.0" where "a" is the original name, ma

Re: [Python-Dev] Tricky way of of creating a generator via a comprehension expression

Serhiy Storchaka wrote: Ivan explained that this function should be rough equivalent to def f(): t = [(yield i) for i in range(3)] return (x for x in t) This seems useless to me. It turns a lazy iterator into an eager one, which is a gross violation of the author's intent in

Re: [Python-Dev] Tricky way of of creating a generator via a comprehension expression

Paul Moore wrote: has anyone confirmed why a function scope was considered necessary at the time of the original implementation, but it's apparently not now? At the time I got the impression that nobody wanted to spend the time necessary to design and implement a subscope mechanism. What's chan

Re: [Python-Dev] Tricky way of of creating a generator via a comprehension expression

Ivan Levkivskyi wrote: "People sometimes want to refactor for-loops containing `yield` into a comprehension By the way, do we have any real-life examples of people wanting to do this? It might help us decide what the semantics should be. -- Greg ___

Re: [Python-Dev] Tricky way of of creating a generator via a comprehension expression

Ivan Levkivskyi wrote: On 23 November 2017 at 05:44, Greg Ewing <mailto:greg.ew...@canterbury.ac.nz>> wrote: def g(): return ((yield i) for i in range(10)) I think this code should be just equivalent to this code def g(): temp = [(yield i) for i in

Re: [Python-Dev] Tricky way of of creating a generator via a comprehension expression

Ivan Levkivskyi wrote: "People sometimes want to refactor for-loops containing `yield` into a comprehension but that doesn't work (particularly because of the hidden function scope) - lets make it a SyntaxError" Personally I'd be fine with removing the implicit function scope from comprehensio

Re: [Python-Dev] Tricky way of of creating a generator via a comprehension expression

Ivan Levkivskyi wrote: The key idea is that neither comprehensions nor generator expressions should create a function scope surrounding the `expr` I don't see how you can avoid an implicit function scope in the case of a generator expression, though. And I can't see how to make yield in a gener

Re: [Python-Dev] Tricky way of of creating a generator via a comprehension expression

Paul Moore wrote: 3. List comprehensions are the same as list(the equivalent generator expression). I don't think that's ever been quite true -- there have always been odd cases such as what happens if you raise StopIteration in list(generator_expression). To my mind, these equivalences have n

Re: [Python-Dev] Tricky way of of creating a generator via a comprehension expression

Paul Moore wrote: At the moment, I know I tend to treat Python semantics as I always did, but with an implicit proviso, "unless async is involved, when I can't assume any of my intuitions apply". That's *not* a good situation to be in. It's disappointing that PEP 3152 was rejected, because I th

Re: [Python-Dev] Tricky way of of creating a generator via a comprehension expression

Ivan Levkivskyi wrote: while `g = list((yield i) for i in range(3))` is defined as this code: def __gen(): for i in range(3): yield (yield i) g = list(__gen()) Since this is almost certainly not what was intended, I think that 'yield' inside a generator expression shoul

Re: [Python-Dev] module customization

Ethan Furman wrote: The second way is fairly similar, but instead of replacing the entire sys.modules entry, its class is updated to be the class just created -- something like sys.modules['mymod'].__class__ = MyNewClass . If the recent suggestion to replace the global namespace dict with the

Re: [Python-Dev] Standardise the AST (Re: PEP 563: Postponed Evaluation of Annotations)

Guido van Rossum wrote: But Python's syntax changes in nearly every release. The changes are almost always additions, so there's no reason why the AST can't remain backwards compatible. the AST level ... elides many details (such as whitespace and parentheses). That's okay, because the AST

[Python-Dev] Standardise the AST (Re: PEP 563: Postponed Evaluation of Annotations)

Guido van Rossum wrote: The PEP answers that clearly (under Implementation): > If an annotation was already a string, this string is preserved > verbatim. This bothers me, because it means the transformation from what you write in the source and the object you get at run time is not reversib

Re: [Python-Dev] PEP 563: Postponed Evaluation of Annotations

Ethan Furman wrote: Contriwise, "annotation_strings" sounds like a different type of annotation -- they are now being stored as strings, instead of something else. How about "annotations_as_strings"? -- Greg ___ Python-Dev mailing list Python-Dev@py

Re: [Python-Dev] [python-committers] Enabling depreciation warnings feature code cutoff

Tres Seaver wrote: IIUC, that would be as expected: you would see the warnings when running your test suite exercising that imported code (which should run with all warnings enabled), but not when running the app. But then what benefit is there in turning on deprecation warnings automatically

Re: [Python-Dev] PEP 563: Postponed Evaluation of Annotations

Guido van Rossum wrote: I did not assume totally opaque -- but code objects are not very introspection friendly (and they have no strong compatibility guarantees). If I understand the proposal correctly, there wouldn't be any point in trying to introspect the lambdas/thunks/whatever. They're on

Re: [Python-Dev] [python-committers] Enabling depreciation warnings feature code cutoff

On 8 November 2017 at 19:21, Antoine Pitrou wrote: The idea that __main__ scripts should get special treatment here is entirely gratuitous. When I'm writing an app in Python, very often my __main__ is just a stub that imports the actual functionality from another module to get the benefits of

Re: [Python-Dev] \G (match last position) regex operator non-existant in python?

Guido van Rossum wrote: From this I understand that when using e.g. findall() it forces successive matches to be adjacent. Seems to me this would be better addressed using an option to findall() rather than being part of the regex. That would avoid the issue of where to keep the state. -- Greg

Re: [Python-Dev] Memory bitmaps for the Python cyclic garbage collector

Tim Peters wrote: In that case, it's because Python _does_ mutate the objects' refcount members under the covers, and so the OS ends up making fresh copies of the memory anyway. Has anyone ever considered addressing that by moving the refcounts out of the objects and keeping them somewhere else

Re: [Python-Dev] PEP 550 v4

Elvis Pranskevichus wrote: By default, generators reference an empty LogicalContext object that is allocated once (like the None object). We can do that because LCs are immutable. Ah, I see. That wasn't clear from the implementation, where gen.__logical_context__ = contextvars.LogicalCon

Re: [Python-Dev] PEP 550 v4

There are a couple of things in the PEP I'm confused about: 1) Under "Generators" it says: once set in the generator, the context variable is guaranteed not to change between iterations; This suggests that you're not allowed to set() a given context variable more than once in a given gene

Re: [Python-Dev] PEP 550 v4

There is one thing I misunderstood. Since generators and coroutines are almost exactly the same underneath, I had thought that the automatic logical_context creation for generators was also going to apply to coroutines, but from reading the PEP again it seems that's not the case. Somehow I missed

Re: [Python-Dev] PEP 550 v4

Yury Selivanov wrote: I understand what Koos is talking about, but I really don't follow you. Using the "with-statements to be skipped" language is very confusing and doesn't help to understand you. If I understand correctly, instead of using a context manager, your fractions example could be

Re: [Python-Dev] PEP 550 v4

Yury Selivanov wrote: def foo(): var = ContextVar() var.set(1) for _ in range(10**6): foo() If 'var' is strongly referenced, we would have a bunch of them. Erk. This is not how I envisaged context vars would be used. What I thought you would do is this: my_contex

Re: [Python-Dev] PEP 550 v4

Yury Selivanov wrote: The PEP gives you a Task Local Storage, where Task is: 1. your single-threaded code 2. a generator 3. an async task If you correctly use context managers, PEP 550 works intuitively and similar to how one would think that threading.local() should work. My version works *m

Re: [Python-Dev] PEP 550 v4

Yury Selivanov wrote: 1. So essentially this means that we will have one "local context" per context manager storing one value. I can't see that being a major problem. Context vars will (I hope!) be very rare things, and needing to change a bunch of them in one function ought to be rarer still.

Re: [Python-Dev] PEP 550 v4

Yury Selivanov wrote: I still think that giving Python programmers one strong rule: "context mutation is always isolated in generators" makes it easier to reason about the EC and write maintainable code. Whereas I think it makes code *harder* to reason about, because to take advantage of it you

Re: [Python-Dev] PEP 550 v4

Guido van Rossum wrote: Yeah, so my claim this is simply a non-problem, and you've pretty much just proved that by failing to come up with pointers to actual code that would suffer from this. Clearly you're not aware of any such code. In response I'd ask Yuri to come up with examples of real c

Re: [Python-Dev] PEP 550 v4

Yury Selivanov wrote: It would be great if you or Greg could show a couple of real-world examples showing the "issue" (with the current PEP 550 APIs/semantics). Here's one way that refactoring could trip you up. Start with this: async def foo(): calculate_something() #in a corou

Re: [Python-Dev] PEP 550 v4

Guido van Rossum wrote: This feels like a very abstract argument. I have a feeling that context state propagating out of a call is used relatively rarely -- it must work for cases where you refactor something that changes context inline into a utility function (e.g. decimal.setcontext()), but

Re: [Python-Dev] PEP 550 v4

Nathaniel Smith wrote: The implementation strategy changed radically between v1 and v2 because of considerations around generator (not coroutine) semantics. I'm not sure what more it can do to dispel these feelings :-). I can't say the changes have dispelled any feelings on my part. The implem

Re: [Python-Dev] PEP 550 v4

Nathaniel Smith wrote: Literally the first motivating example at the beginning of the PEP ('def fractions ...') involves only generators, not coroutines, and only works correctly if generators get special handling. (In fact, I'd be curious to see how Greg's {push,pop}_local_storage could handle t

Re: [Python-Dev] PEP 550 v4

Ivan Levkivskyi wrote: Normal generators fall out from this "scheme", and it looks like their behavior is determined by the fact that coroutines are implemented as generators. This is what I disagree with. Generators don't implement coroutines, they implement *parts* of coroutines. We want "t

Re: [Python-Dev] PEP 550 v4

Yury Selivanov wrote: Greg, have you seen this new section: https://www.python.org/dev/peps/pep-0550/#should-yield-from-leak-context-changes That section seems to be addressing the idea of a generator behaving differently depending on whether you use yield-from on it. I never suggested that, a

Re: [Python-Dev] PEP 550 v4

Yury Selivanov wrote: Question: how to write a context manager with contextvar.new? var = new_context_var() class CM: def __enter__(self): var.new(42) with CM(): print(var.get() or 'None') My understanding that the above code will print "None", because "

Re: [Python-Dev] Inplace operations for PyLong objects

Chris Angelico wrote: This particular example is safe, because the arguments get passed individually - so 'args' has one reference, plus there's one more for the actual function call However, that's also true when you use the += operator, so if the optimisation is to trigger at all in any usefu

Re: [Python-Dev] PEP 550 v4

Yury Selivanov wrote: BTW we already have mechanisms to always propagate context to the caller -- just use threading.local() or a global variable. But then you don't have a way to *not* propagate the context change when you don't want to. Here's my suggestion: Make an explicit distinction bet

Re: [Python-Dev] PEP 550 v4

Yury Selivanov wrote: While we want "yield from" to have semantics close to a function call, That's not what I said! I said that "yield from foo()" should have semantics close to a function call. If you separate the "yield from" from the "foo()", then of course you can get different behaviours.

Re: [Python-Dev] PEP 550 v4

Yury Selivanov wrote: Consider the following generator: def gen(): with decimal.context(...): yield We don't want gen's context to leak to the outer scope That's understandable, but fixing that problem shouldn't come at the expense of breaking the ability to refacto

Re: [Python-Dev] PEP 550 v4

Yury Selivanov wrote: I saying that the following should not work: def nested_gen(): set_some_context() yield def gen(): # some_context is not set yield from nested_gen() # use some_context ??? And I'm saying it *should* work, otherwise it breaks o

Re: [Python-Dev] PEP 550 v4

Yury Selivanov wrote: On Mon, Aug 28, 2017 at 1:33 PM, Stefan Krah wrote: [..] * Context managers like decimal contexts, numpy.errstate, and warnings.catch_warnings. The decimal context works like this: 1) There is a default context template (user settable). 2) Whenever the first operati

Re: [Python-Dev] Scope, not context? (was Re: PEP 550 v3 naming)

Barry Warsaw wrote: I actually think Python’s scoping rules are fairly easy to grasp, The problem is that the word "scope", as generally used in relation to programming languages, has to do with visibility of names. A variable is "in scope" at a particular point in the code if you can acccess i

Re: [Python-Dev] Scope, not context? (was Re: PEP 550 v3 naming)

Barry Warsaw wrote: This is my problem with using "Context" for this PEP. Although I can't keep up with all names being thrown around, Not sure whether it helps, but a similar concept in some Scheme dialects is called a "fluid binding". e.g. Section 5.4 of http://www.scheme.com/csug8/binding.

Re: [Python-Dev] PEP 550 v3 naming

Guido van Rossum wrote: Perhaps the latter can be shortened to just ContextStack (since the Foo part can probably be guessed from context. :-) -0.9, if I saw something called ContextStack turn up in a traceback I wouldn't necessarily jump to the conclusion that it was a stack of FooContexts ra

Re: [Python-Dev] PEP 550 v3

Ethan Furman wrote: So I like ExecutionContext for the stack of WhateverWeCallTheOtherContext contexts. But what do we call it? How about ExecutionContextFrame, by analogy with stack/stack frame. -- Greg ___ Python-Dev mailing list Python-Dev@pytho

Re: [Python-Dev] PEP 550 v3 naming

Yury Selivanov wrote: I can certainly see how "ContextFrame" can be correct if we think about "frame" as a generic term, but in Python, people will inadvertently think about a connection with frame objects/stacks. Calling it ExecutionContextFrame rather than just ContextFrame would make it clea

Re: [Python-Dev] Impact of Namedtuple on startup time

Barry Warsaw wrote: namedtuple is great and clever, but it’s also a bit clunky. It has a weird signature and requires a made up type name. Maybe a metaclass could be used to make something like this possible: class Foo(NamedTuple, fields = 'x,y,z'): ... Then the name is explicit an

Re: [Python-Dev] PEP 7 and braces { .... } on if

Seems like a good idea to tighten it up. If a style guide is going to say "you can either do X or not do X", it might as well not mention X at all. :-) -- Greg ___ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/p

Re: [Python-Dev] "Micro-optimisations can speed up CPython"

Serhiy Storchaka wrote: In early ages of C structures didn't create namespaces, and member names were globals. That would certainly explain the origins of it, but I'm pretty sure it wasn't the case by the time Python was invented. So Guido must have liked it for other reasons. -- Greg

Re: [Python-Dev] "Micro-optimisations can speed up CPython"

Steven D'Aprano wrote: What does "tp" stand for? Type something, I guess. I think it's just short for "type". There's an old tradition in C of giving member names a short prefix reminiscent of the type they belong to. Not sure why, maybe someone thought it helped readability. -- Greg _

Re: [Python-Dev] "Micro-optimisations can speed up CPython"

David Wilson wrote: They're referred to as slots throughout typeobject.c That's probably where he got the term from. But it really refers to C-level fields in the type object. Magic methods that don't correspond to C-level type fields are not called slots. -- Greg _

Re: [Python-Dev] Aligning the packaging.python.org theme with the rest of the docs

M.-A. Lemburg wrote: In my role as PSF TM committee member, it's often painful to have to tell community members that they cannot use e.g. really nice looking variants of the Python logo for their projects. Let's not add more pain. But it's always within the PSF's power to give that community m

Re: [Python-Dev] Micro-optimizations by adding special-case bytecodes?

When testing things like this, as well as testing whether it speeds up your target cases, remember to check that it doesn't slow everything else down due to the increased size of the eval code pushing something out of instruction cache or some such effect. -- Greg

Re: [Python-Dev] Set program name through exec -a or environment variable

Oleg Broytman wrote: On Sat, Mar 18, 2017 at 10:27:58AM -0500, Ryan Gonzalez wrote: exec -a would seem to end up setting argv[0] on the CPython interpreter itself, which I don't think is the desired effect... That's exactly what OP asked -- how to change that? Maybe python itself shoul

Re: [Python-Dev] re performance

Armin Rigo wrote: The theoretical kind of regexp is about giving a "yes/no" answer, whereas the concrete "re" or "regexp" modules gives a match object, which lets you ask for the subgroups' location, for example. Another issue is that the theoretical engine has no notion of greedy/non-greedy ma

Re: [Python-Dev] Optimizing list.sort() by checking type in advance

Elliot Gorokhovsky wrote: I ran the benchmark a couple of times and the numbers seem to exactly line up something like one in five times; perhaps not that crazy considering they're executing nearly the same code? Could this be a result of a time being measured in seconds somewhere and then di

Re: [Python-Dev] PyWeakref_GetObject() borrows its reference from... whom?

Random832 wrote: Or is this a special kind of lock that you can "assert isn't locked" without locking it for yourself, and INCREF/DECREF does so? I don't think that would work. It might be unlocked at the moment you test it, but someone might lock it between then and the following INCREF/DECREF

Re: [Python-Dev] PyWeakref_GetObject() borrows its reference from... whom?

Nathaniel Smith wrote: IIRC to handle this gilectomy adds per-object mutexes that you have to hold whenever you're mucking around with that object's internals. What counts as "mucking around with the object's internals", though? If I do the C equivalent of: x = somedict[5] x.dosomething

Re: [Python-Dev] PyWeakref_GetObject() borrows its reference from... whom?

On Tue, Oct 11, 2016 at 4:03 AM, Paul Moore wrote: If you have an object that forever owns a reference to another object, it's safe to return borrowed references. Even if there are such cases, it seems we're going to have to be a lot more careful about identifying them. It might be safer not

Re: [Python-Dev] PyWeakref_GetObject() borrows its reference from... whom?

Larry Hastings wrote: In contrast, the "borrowed" reference returned by PyWeakRef_GetObject() seems to be "borrowed" from some unspecified entity. It's a delocalised quantum reference, borrowing a little bit from all strong references in existence. :-) -- Greg _

Re: [Python-Dev] TextIO seek and tell cookies

Ben Leslie wrote: But the idea of transmitting these offsets outside of a running process is not something that I had anticipated. It got me thinking: is there a guarantee that these opaque values returned from tell() is stable across different versions of Python? Are they even guaranteed to wo

Re: [Python-Dev] Python 3.6 dict becomes compact and gets a private version; and keywords become ordered

MRAB wrote: On 2016-09-13 07:57, Mark Lawrence via Python-Dev wrote: "tables the idea" has the US meaning of close it down, not the UK meaning of open it up? :) A better phrase would've been "shelves the idea". There's even a module in Python called "shelve", which makes it Pythonic. :-)

Re: [Python-Dev] Do PEP 526 type declarations define the types of variables or not?

Mark Shannon wrote: Unless of course, others may have a different idea of what the "type of a variable" means. To me, it means it means that for all assignments `var = expr` the type of `expr` must be a subtype of the variable, and for all uses of var, the type of the use is the same as the typ

Re: [Python-Dev] Please reject or postpone PEP 526

On Sun, Sep 04, 2016 at 12:31:26PM +0100, Mark Shannon wrote: As defined in PEP 526, I think that type annotations become a hindrance to type inference. In Haskell-like languages, type annotations have no ability to influence whether types can be inferred. The compiler infers a type for everyt

Re: [Python-Dev] PEP 525, third round, better finalization

Nick Coghlan wrote: For synchronous code, that's a relatively easy burden to push back onto the programmer - assuming fair thread scheduling, a with statement can ensure reliably ensure prompt resource cleanup. That assurance goes out the window as soon as you explicitly pause code execution ins

Re: [Python-Dev] PEP 467: last round (?)

Ethan Furman wrote: The problem with only having `bchr` is that it doesn't help with `bytearray`; the problem with not having `bchr` is who wants to write `bytes.fromord`? If we called it 'bytes.fnord' (From Numeric Ordinal) people would want to write it just for the fun factor. -- Greg _

Re: [Python-Dev] What should a good type checker do? (was: Please reject or postpone PEP 526)

Chris Angelico wrote: Forcing people to write 1.0 just to be compatible with 1.5 will cause a lot of annoyance. Indeed, this would be unacceptable IMO. The checker could have a type 'smallint' that it considers promotable to float. But that wouldn't avoid the problem entirely, because e.g. add

Re: [Python-Dev] When to use EOFError?

Nikolaus Rath wrote: I think EOFError conveys more information. UnpicklingError can mean a lot of things, EOFError tells you the precise problem: pickle expected more data, but there was nothing left. I think EOFError should be used for EOF between pickles, but UnpicklingError should be used fo

Re: [Python-Dev] PEP 487: Simpler customization of class creation

Nick Coghlan wrote: Something that isn't currently defined in PEP 520 ... is where descriptors implicitly defined via __slots__ will appear relative to other attributes. In the place where the __slots__ attribute appears? -- Greg ___ Python-Dev maili

Re: [Python-Dev] Why does base64 return bytes?

Steven D'Aprano wrote: I'm satisfied that the choice made by Python is the right choice, and that it meets the spirit (if, arguably, not the letter) of the RFC. IMO it meets the letter (if you read it a certain way) but *not* the spirit. -- Greg ___

Re: [Python-Dev] Why does base64 return bytes?

Simon Cross wrote: If we only support one, I would prefer it to be bytes since (bytes -> bytes -> unicode) seems like less overhead and slightly conceptually clearer than (bytes -> unicode -> bytes), Whereas bytes -> unicode, followed if needed by unicode -> bytes, seems conceptually clearer to

Re: [Python-Dev] Why does base64 return bytes?

Stephen J. Turnbull wrote: The RFC is unclear on this point, but I read it as specifying the ASCII coded character set, not the ASCII repertoire of (abstract) characters. Well, I think you've misread it. Or at least there is a more general reading possible that is entirely consistent with the

Re: [Python-Dev] Why does base64 return bytes?

Stephen J. Turnbull wrote: it does refer to *encoded* characters as the output of the encoding process: > The encoding process represents 24-bit groups of input bits > as output strings of 4 encoded characters. The "encoding" being referred to there is the encoding from input bytes

Re: [Python-Dev] Why does base64 return bytes?

R. David Murray wrote: The fundamental purpose of the base64 encoding is to take a series of arbitrary bytes and reversibly turn them into another series of bytes in which the eighth bit is not significant. No, it's not. If that were its only purpose, it would be called base128, and the RFC wou

Re: [Python-Dev] Why does base64 return bytes?

Joao S. O. Bueno wrote: The arguments about compactness and what is most likely to happen next applies (transmission trhough a binary network protocol), I'm not convinced that this is what is most likely to happen next *in a Python program*. How many people implement their own binary network pr

Re: [Python-Dev] BDFL ruling request: should we block forever waiting for high-quality random bits?

Steven D'Aprano wrote: - Linux /dev/urandom doesn't block, but it might return predictable, poor-quality pseudo-random bytes (i.e. a potential exploit); - Other OSes may block for potentially many minutes (i.e. a potential DOS). It's even possible that it could block *forever*. There wa

Re: [Python-Dev] Smoothing the transition from Python 2 to 3

On Jun 8, 2016 4:04 PM, "Neil Schemenauer" > wrote: > > I've temporarily named it "Pragmatic Python". I'd like a better > name if someone can suggest one. Maybe something like Perverted, > Debauched or Impure Python. Python Two and Three Quarters. -- Greg _

Re: [Python-Dev] Python parser performance optimizations

Steven D'Aprano wrote: That can't be right. How can you reduce memory usage by more than one hundred percent? That would mean you have saved more memory than was originally used and are now using a negative amount of memory. It emails an order for more RAM to Amazon, who send out a robot drone

Re: [Python-Dev] Adding NewType() to PEP 484

Steven D'Aprano wrote: TypeAlias? Because A is an alias for int? That suggests it's just another name for the same type, but it's not. It's a distinct type as far as the static type checker is concerned. -- Greg ___ Python-Dev mailing list Python-De

Re: [Python-Dev] Adding NewType() to PEP 484

Guido van Rossum wrote: Also -- the most important thing. :-) What to call these things? We're pretty much settled on the semantics and how to create them (A = NewType('A', int)) but what should we call types like A when we're talking about them? "New types" sounds awkward. Fake types? Virtual

Re: [Python-Dev] file system path protocol PEP

Paul Moore wrote: On 13 May 2016 at 17:57, Ethan Furman wrote: 1) What is a wallet garden? I assumed he meant "walled garden" Works either way -- you'd want a wall around your wallet garden to stop people stealing your wallets. -- Greg ___ Pytho

Re: [Python-Dev] Return type of alternative constructors

Guido van Rossum wrote: We could also consider this a general weakness of the "alternative constructors are class methods" pattern. If instead these alternative constructors were folded into the main constructor (e.g. via special keyword args) it would be altogether clearer what a subclass shou

Re: [Python-Dev] Bug in 2to3 concerning import statements?

Brett Cannon wrote: There's all sorts of weird stuff going on in that import, like having a dot in the `from` part of the import instead of doing `from .py2exe import mf as modulefinder`. If I did that, it would try to import mf from the py2exe submodule rather than the global one. In hindsi

[Python-Dev] Bug in 2to3 concerning import statements?

It seems that 2to3 is a bit simplistic when it comes to translating import statements. I have a module GUI.py2exe containing: import py2exe.mf as modulefinder 2to3 translates this into: from . import py2exe.mf as modulefinder which is a syntax error. It looks like 2to3 is getting confus

Re: [Python-Dev] pathlib - current status of discussions

Chris Barker - NOAA Federal wrote: Why in the world do the os.path functions need to work with Path objects? So that applications using path objects can pass them to library code that uses os.path to manipulate them. I'm confused about what a bytes path IS -- is it encoded? It's a sequence

Re: [Python-Dev] Challenge: Please break this! (a.k.a restricted mode revisited)

Jon Ribbens wrote: So far it looks like blocking "_*" and the frame object attributes appears to be sufficient. Even if your sandbox as it currently exists is secure, it's only an extremely restricted subset. You seem to be assuming that if your technique works so far, then it can be extended t

Re: [Python-Dev] Pathlib enhancements - acceptable inputs and outputs for __fspath__ and os.fspath()

Ethan Furman wrote: # after new protocol with bytes/str support def zingar(a_path): a_path = fspath(a_path) if not isinstance(a_path, (bytes,str)): raise TypeError('bytes or str required') ... I think that one would be just def zingar(a_path): a_path =

Re: [Python-Dev] Pathlib enhancments - method name only

Nick Coghlan wrote: Similar to my proposal for dealing with DirEntry.path being a bytes-like object, I'd like to suggest raising TypeError in __fspath__ if the request is nonsensical for the currently running system - *nix systems can *manipulate* Windows paths (and vice-versa), but actually tryi

Re: [Python-Dev] Pathlib enhancments - method name only

On 9 April 2016 at 23:02, R. David Murray wrote: That is, a 'filename' is the identifier we've assigned to this thing pointed to by an inode in linux, but an os path is a text representation of the path from the root filename to a specified filename. That is, the path *is* the name, so to say

Re: [Python-Dev] Pathlib enhancments - method name only

Eric Snow wrote: All this matters because it impacts the value returned from __ospath__(). Should it return the string representation of the path for the current OS or some standardized representation? What standardized representation? I'm not aware of such a thing. I'd expect the former. H

Re: [Python-Dev] pathlib (was: Defining a path protocol)

Nick Coghlan wrote: We want to be able to readily use the protocol helper in builtin modules like os and low level Python modules like os.path, which means we want it to be much lower down in the import hierarchy than pathlib. Also, it's more general than that. It works on any object that wants

Re: [Python-Dev] Pathlib enhancments - method name only

Brett Cannon wrote: Depends if you use `/` or `\` as your path separator Or whether your pathnames look entirely different, e.g VMS: device:[topdir.subdir.subsubdir]filename.ext;version Pathnames are very much OS-dependent in both syntax *and* semantics. Even the main two in use today (un

Re: [Python-Dev] Defining a path protocol

Chris Angelico wrote: -1 for __os_path__, unless it's reasonable to justify it as "most of the standard library uses Path objects, but os.path uses strings, so before you pass a Path to anything in os.path, you call path.ospath() on it, which calls __os_path__()". A less roundabout interpretati

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