[issue47257] add methods to get first and last elements of a range
paul rubin added the comment: Oh nice, I didn't realize you could do that. len(range) and bool(range) (to test for empty) also work. Ok I guess this enhancement is not needed. I will close ticket, hope that is procedurally correct, otherwise feel free to fix. Thanks. -- resolution: -> rejected stage: -> resolved status: open -> closed ___ Python tracker <https://bugs.python.org/issue47257> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue47257] add methods to get first and last elements of a range
New submission from paul rubin : Inspired by a question on comp.lang.python about how to deal with an int set composed of integers and ranges. Range objects like range(1,5,2) contain start, stop, and step values, but it's messy and potentially tricky to get the actual first and last values of the range. Examples: range(1,5,2) - first = 1, last = 3 range (5, 1, 2) - range is empty, first = last = None range(5, 1, -1) - first is 5, last is 2 Note in the case where the range is not empty, you can get the "last" by a messy calculation but it's easier to pick the first element from the reverse iterator. But then you might forget to catch the stopiteration exception in the case that the list is empty. The same goes for the first element, roughly. And constructing the iterators just to pick one element seems like unnecessary overhead. So it is better to have actual methods for these, with type Optional[int]. Then mypy should remind you to check for the empty case if you forget. -- messages: 416962 nosy: phr priority: normal severity: normal status: open title: add methods to get first and last elements of a range type: enhancement ___ Python tracker <https://bugs.python.org/issue47257> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue44571] itertools: takedowhile()
paul rubin added the comment: Bah, the above doesn't work in the cases where the iterator is empty or (different symptom) where the tail part is empty. Rather than posting a corrected version (unless someone wants it) I'll just say not to use that code fragment, but that the intended API still looks reasonable. I do support having some kind of solution but don't want to keep stretching out an already closed discussion unless people think there is more to say. -- ___ Python tracker <https://bugs.python.org/issue44571> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue44571] itertools: takedowhile()
paul rubin added the comment: Oh wow, before_and_after will go into the itertools module per that patch? I found this issue while looking for a way to this, but had written the following implementation: def span(pred, xs): # split xs into two iterators a,b where a() is the prefix of xs # that satisfies the predicate, and b() is the rest of xs. # Similar to Data.List.Span in Haskell. ixs = iter(xs) t = None def a(): nonlocal t for x in ixs: if pred(x): yield x else: break t = x def b(): return itertools.chain([t], ixs) return a, b def tspan(): # test xs = [1,3,5,2,4,6,8] def odd(x): return x%2==1 # This should print [1,3,5] then [2,4,6,8] for p in span(odd, xs): print(list(p())) -- nosy: +phr ___ Python tracker <https://bugs.python.org/issue44571> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue40734] /usr/bin surprisingly in sys.path under IDLE
paul rubin added the comment: Yes as mentioned I'm running Debian GNU/Linux, not Windows. By "idle is installed in /usr/bin" I mean that it is an executable shell script stored at /usr/bin/idle . Yes, shell prompt is the $ prompt to bash. When I run "python3 -m idlelib", /usr/bin does not appear in sys.path. "python -m idlelib" attempts to run python2 and I don't have python2 idle installed. I'll see if I can figure out what's going on with sys.path in the user process. The explanation about the two processes was helpful. Thanks. -- ___ Python tracker <https://bugs.python.org/issue40734> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue40734] /usr/bin surprisingly in sys.path under IDLE
paul rubin added the comment:
I'm using Debian 10 MATE live install and have been running IDLE by clicking an
icon on the top panel, but I just tried running IDLE from the shell prompt in a
terminal window, and also see /usr/bin in the path. In both cases, the output
of os.system('pwd').read() is my home directory. IDLE itself is installed in
/usr/bin .
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[issue40734] /usr/bin surprisingly in sys.path under IDLE
paul rubin added the comment: Matthias, I get the same result you do when I run python from the shell command line. I see /usr/bin in the path when I import sys and print sys.path from inside IDLE. In other words this is an IDLE configuration oddity. Again I don't know if it's a bug. It's perplexing though. -- ___ Python tracker <https://bugs.python.org/issue40734> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue40733] Make IDLE doc more visible, mention in main python docs page
paul rubin added the comment: I think I used duckduckgo to find the docs. They don't change much between versions and I was trying to find how to do a specific thing. My installation has the docs included but it didn't explain how to do what I wanted, so I had hoped there was a more complete doc on docs.python.org. Unfortunately it turned out to be the same doc. The functionality I wanted (to put a startup script in .idlerc) seems to not exist though. I'll research workarounds a bit further and possibly open an RFE if people think that sounds right. -- ___ Python tracker <https://bugs.python.org/issue40733> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue40733] mention IDLE in main python docs page
Change by paul rubin : -- title: mention IDLE in main python ocs page -> mention IDLE in main python docs page ___ Python tracker <https://bugs.python.org/issue40733> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue40734] /usr/bin surprisingly in sys.path under IDLE
New submission from paul rubin : This is in the standard python 3.7.3 install under Debian 10. It's possible that this is on purpose, and it's (separately) possible that the Debian packagers did this for some reason. I'm not sure it's a bug but am reporting it as it's an oddity that might warrant looking into. When I look at sys.path in the IDLE shell, the path includes /usr/bin, which is not there under the normal python prompt. Since /usr/bin is not a place where python modules usually live, it's a bit strange to find it on the path. It doesn't seem healthy since it could lead to surprises. But maybe I'm missing something. Feel free to close this if the inclusion is intentional. -- assignee: terry.reedy components: IDLE messages: 369643 nosy: phr, terry.reedy priority: normal severity: normal status: open title: /usr/bin surprisingly in sys.path under IDLE type: behavior versions: Python 3.7 ___ Python tracker <https://bugs.python.org/issue40734> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue40733] mention IDLE in main python ocs page
New submission from paul rubin : The IDLE documentation is in https://docs.python.org/3/library/idle.html which is not where I'd have thought to look for it, since I think of IDLE as an application rather than a library. So I looked for it on the main docs page, docs.python.org, and didn't find it there. I ended up finding it by web search. I guess its current location is reasonable, but maybe a link to it could be included in docs.python.org's main page left side navigation panel, or IDLE could simply be mentioned in the entry for library documentation. -- assignee: docs@python components: Documentation messages: 369640 nosy: docs@python, phr priority: normal severity: normal status: open title: mention IDLE in main python ocs page type: enhancement ___ Python tracker <https://bugs.python.org/issue40733> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue40411] frozen collection.Counter
paul rubin added the comment: Note: PEP 603 may essentially take care of this, if it is accepted. -- ___ Python tracker <https://bugs.python.org/issue40411> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue40028] Math module method to find prime factors for non-negative int n
paul rubin added the comment: I don't think the interface needs much bikeshedding, as long as the implementer chooses something reasonable. E.g. factor(30) gives the list [2,3,5]. Implementation is harder if you want to handle numbers of non-trivial size. Neal Koblitz's book "A Course in Number Theory and Cryptogoraphy" has good coverage of factoring algorithms. To factor numbers up to 2**64, Pollard's rho method is simple to code and has always worked for me, but I don't know if there are specific numbers in that range that could give it trouble. For bigger numbers you need fancier algorithms and eventually fancy hardware and long computing runs. Part of a design discussion would include trying to decide the scope of such a module. -- ___ Python tracker <https://bugs.python.org/issue40028> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue40623] JSON streaming
paul rubin added the comment: Also I didn't know about ndjson (I just looked at it, ndjson.org) but its existence and formalization is even more evidence that this is useful. I'll check what the two different python modules linked from that site do that's different from your example of iterating through the file by lines. -- ___ Python tracker <https://bugs.python.org/issue40623> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue40623] JSON streaming
paul rubin added the comment: It's coming back to me, I think I used the no-separator format because I made the multi-document input files by using json.dump after opening the file in append mode. That seems pretty natural. I figured the wikipedia article and the json.tool patch just released were evidence that there is interest in this. The approach of writing newlines between the docs and iterating through lines is probably workable though. I don't know why I didn't do that before. I might not have been sure that json docs never contain newlines. Really it would be nice if json.load could read in anything that json.dump could write out (including with the indent parameter), but that's potentially more complicated and might conflict with the json spec. -- ___ Python tracker <https://bugs.python.org/issue40623> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue40623] JSON streaming
paul rubin added the comment: Note: the function in my attached file wants no separation at all between the json docs (rather than a newline between them), but that was ok for the application I wrote it for some time back. I forgot about that when first writing this rfe so thought I better clarify. -- ___ Python tracker <https://bugs.python.org/issue40623> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue40623] JSON streaming
Change by paul rubin : Added file: https://bugs.python.org/file49154/jsonstream.py ___ Python tracker <https://bugs.python.org/issue40623> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue40623] JSON streaming
New submission from paul rubin : This is a well-explored issue in other contexts: https://en.wikipedia.org/wiki/JSON_streaming There is also a patch for it in json.tool, for release in 3.9: https://bugs.python.org/issue31553 Basically it's often convenient to have a file containing a list of json docs, one per line. However, there is no convenient way to read them back in one by one, since json.load(filehandle) barfs when it sees the unexpected newline at the end of the first doc. It would be great if the json module itself had a function to handle this. I have an awful hack that I use myself, that is not suitable for a production library, but I'll attach it to show what functionality I'm suggesting. I hope this is simple enough to not need a PEP. Thanks! -- components: Library (Lib) files: jsonstream.py messages: 368823 nosy: phr priority: normal severity: normal status: open title: JSON streaming type: enhancement Added file: https://bugs.python.org/file49153/jsonstream.py ___ Python tracker <https://bugs.python.org/issue40623> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue36027] Support negative exponents in pow() where a modulus is specified.
paul rubin added the comment: https://bugs.python.org/issue457066 The old is new again ;-). -- nosy: +phr ___ Python tracker <https://bugs.python.org/issue36027> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue40028] Math module method to find prime factors for non-negative int n
paul rubin added the comment: I'm the one always asking for more stuff in the stdlib, but above some simplistic approaches this seems out of scope. Doing it usefully above say 2**32 requires fancy algorithms. Better to use some external package that implements that stuff. -- nosy: +phr ___ Python tracker <https://bugs.python.org/issue40028> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue40411] frozen collection.Counter
paul rubin added the comment: Totally tangential: Veky, your ordinal example would work ok in Haskell and you'd have omega work the same way as epsilon0. Take a look at Herman Ruge Jervell's book "Proof Theory" for a really nice tree-based ordinal notation that goes much higher than epsilon0. It would be cool if your student implemented it. Raymond, I agree that ordinals are a very esoteric use of multisets ;). -- ___ Python tracker <https://bugs.python.org/issue40411> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue40411] frozen collection.Counter
paul rubin added the comment: Yeah I think the basic answer to this ticket is "Python doesn't really have multisets and a proposal to add them should go somewhere else". Fair enough-- consider the request withdrawn from here. Regarding minimalism vs completeness, regarding some feature X (say X is multisets), it's reasonable per minimalism to decide not to have X. But if on weighing the use cases you decide to have X after all, I think it's best to implement X properly and completely with all the edge cases handled, rather than implement a half-baked subset. That was something Java was historically very good at and Python wasn't. I guess that is one for the theorists though. Thanks everyone. -- ___ Python tracker <https://bugs.python.org/issue40411> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue40411] frozen collection.Counter
paul rubin added the comment: Oops I meant "*without* 100s of third party modules" in the case of ruby gems or npm. There are just a few pip modules that I really use all the time, most notably bs4. I continue to use urllib/urllib2 instead of requests because I'm used to them and because they eliminate an unnecessary dependency. -- ___ Python tracker <https://bugs.python.org/issue40411> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue40411] frozen collection.Counter
paul rubin added the comment:
Kyle, thanks, I saw your comment after posting my own, and I looked at
Raymond's mailing list post that you linked. I do think that "completing the
grid" is a good thing in the cases where it's obvious how to do it (if there's
one and one obvious way, then doing it that way should work), and having
missing combinations in the grid is also a form of interface complexity (expect
subset to work, find that it doesn't, and implement some hack). Also it seems
to me that sets, dicts, bags are basic data objects in many languages these
days, without a lot of design space to move around in. So we don't have to
worry much about constraining future choices. We could just look at Smalltalk
or Ruby or whatever and just do what they did.
However, that is philosophical. I did learn from Raymond's message that
Counter doesn't really attempt to be a multiset implementation. In that case,
it works for what it is made for, so it really then is a separate question of
whether implementing multisets properly is worthwhile. (That's as opposed to
saying we already have a multiset implementation but some functionality is
missing from it).
I dislike the concept of shovelling off basic functionality to 3rd party
libraries. The rejection of that philosophy (Python's old motto "Batteries
included") is one of the things that attracted me to Python in the first place.
Though that value is mostly historical now, I'm sad about the loss. It's
impossible to write a large Ruby or Javascript (npm) application with 100s of
third party modules, every one of which is an attack vector ("supply chain
attack" is the current buzzword), and whose implementations vary widely in
quality and usability. I looked at the docs for Ruby's multiset gem
(https://maraigue.hhiro.net/multiset/) and they are partly in Japanese. Python
has until the past few years managed to keep away from that kind of thing.
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[issue40411] frozen collection.Counter
paul rubin added the comment: Yes, the idea was for them to be hashable, to be used as dict keys. E.g. if you use frozensets to model graphs, you'd use frozen multisets for hypergraphs. My immediate use case involved word puzzles, e.g. treating words as bags of scrabble tiles with letters on them, and finding out what other words you could form from the letters. It is not a pressing need. I'm trying to remember what the other missing operation I ran into was, a few days ago. It may have been subset. I found a workaround but it seemed a bit ugly. It would be nice if Counters could also be thought of as multisets which can do the same things sets can do with unneeded head scratching. It seems like counters and multisets/bags really are different things conceptually. Their operations and implementations overlap, but they are different. E.g. it can make sense for a counter to have a negative count of something, but not for a bag. -- ___ Python tracker <https://bugs.python.org/issue40411> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue1726707] add itertools.ichain function and count.getvalue
paul rubin added the comment: Note, nowadays this is implement as itertools.chain.from_iterable . -- ___ Python tracker <https://bugs.python.org/issue1726707> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue40334] PEP 617: new PEG-based parser
Change by paul rubin : -- nosy: -phr ___ Python tracker <https://bugs.python.org/issue40334> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue40411] frozen collection.Counter
New submission from paul rubin : It would be nice to have frozen Counters analogous to frozensets, so they are usable as dictionary keys. One can of course create frozenset(counter.items()) but that means the set items are tuples rather than the original set elements, so it's no longer quick to check membership. I can work around this in my immediate application but it seems like a shortcoming. There are some other set operations that aren't supported by counters either, that would be nice if they are conceptually multisets. -- components: Library (Lib) messages: 367472 nosy: phr priority: normal severity: normal status: open title: frozen collection.Counter type: enhancement ___ Python tracker <https://bugs.python.org/issue40411> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue40334] PEP 617: new PEG-based parser
paul rubin added the comment: I just saw this. Interesting. Sometimes I use ast.literal_eval to read big, deeply nested data objects. I can probably convert to JSON if necessary but it's another thing to watch out for. I might try to benchmark some of these. -- nosy: +phr ___ Python tracker <https://bugs.python.org/issue40334> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue38333] add type signatures to library function docs
paul rubin added the comment: I don't think we're going to accomplish anything continuing the eternal static-vs-dynamic debate, which in Python's case has already been resolved by adding optional static typing. It's a done deal, and the issue here is just how to document it. Erlang (via the Erlang Dialyzer), Clojure, and Racket have all been down a similar road and gained some value from it. Haskell's Maybe type (its version of Option) works fine. In Python the convention of returning None for a missing value is not great, but we are stuck with it and Option[whatever] is helpful. -- ___ Python tracker <https://bugs.python.org/issue38333> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue38333] add type signatures to library function docs
paul rubin added the comment: At first glance, having a typeclass for each protocol (at least the widely used ones) seems fine. It's inherent in Haskell and a lot of libraries are organized around a common set of typeclasses--look up "Typeclassopedia" for descriptions of them. Certainly the case of abs (which you asked about by name), the typeclass is already there in the typing module. You're right about abs(complex) returning float. Haskell's type signature for abs is "Num a => a -> a" which means the input type is the same as the output. That is a little bit peculiar since the abs of a complex number is complex, but we usually think of abs as a mathematical norm, which is conventionally a real. Anyway, "abs(x: Abs[T]) -> Any" is a better-than-nothing signature for abs, and the docs can comment a little further, and maybe someday it could even do a type-level lookup at typechecking time, i.e. have something like Haskell's "type families". I like to think it's possible to supply reasonable signatures for most functions. I just fixed a bug in something today because bs4 (beautiful soup 4) has no typeshed stub so mypy uses Any for functions like soup.find, instead of Optional[tag]. So the program worked fine as long as find kept returning a tag, but then crashed because it hit a document without a tag and my code didn't check for None. That's something more precise types would have caught at mypy time. -- ___ Python tracker <https://bugs.python.org/issue38333> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue38333] add type signatures to library function docs
paul rubin added the comment: abs takes any value that understands the __abs__ method and returns something of the same type. In fact there is already a type protocol for it: https://mypy.readthedocs.io/en/stable/protocols.html#supportsabs-t So abs's signature would be (x : Abs[T]) -> T where T is a type parameter. I'm sure there are some examples where no good signature is possible, but lots of others are fine. Someone did a Smalltalk study long ago and found that most functions were monomorphic in practice even though Smalltalk is dynamically typed like Python. As a matter of style, Python code tends to be typed even when it doesn't have to be. Not all the time of course. I'm still getting used to types and mypy (I was a py2 holdout til quite recently, and mypy has been a more attractive reason to change than any of the other stuff) and I do keep noticing cases that don't work as I hoped, but it's still a good move in general. -- ___ Python tracker <https://bugs.python.org/issue38333> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue38333] add type signatures to library function docs
paul rubin added the comment: Yes, the suggestion was just for the docs, and since those are intended for human rather than machine consumption, it's fine if there are some blurry cases where there is no signature. Ideally in those cases, the issue should be explained in the doc text. I actually don't see what's wrong with including signatures in the source code as well, as long as doing so doesn't break anyone's existing code. I agree with Veky that one should be very hesitant about breaking existing working code, even if that code relies on undocumented behavior. -- ___ Python tracker <https://bugs.python.org/issue38333> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue38333] add type signatures to library function docs
New submission from paul rubin : It would be nice if the library reference manual had type signatures for all the stdlib functions at some point. It might be possible to extract a lot of them automatically from typeshed and semi-automatically paste them into the doc files. It might also be ok to do this gradually. I can help with this but wouldn't want to take on the entire task. -- assignee: docs@python components: Documentation messages: 353634 nosy: docs@python, phr priority: normal severity: normal status: open title: add type signatures to library function docs type: enhancement versions: Python 3.9 ___ Python tracker <https://bugs.python.org/issue38333> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue24820] IDLE themes for light on dark
Marc Paul Rubin added the comment: Greetings from an idle-dev 'lurker.' Has anyone tested the new dark theme with a Set Breakpoint command? The dark theme is great for me except for this quirk: breakpoints are invisible on my test box. Under the Classic light scheme breakpoints appear on a bright yellow background. Appreciate all the interest and work going into idle these days. I'll add any needed details on request. For starters I'm just wondering whether breakpoints have yet to be tested with this dark theme. Thanks, jayseye (Marc Paul Rubin) -- nosy: +jayseye ___ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue24820> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue5784] raw deflate format and zlib module
paul rubin added the comment: Hey, thanks for updating this. I still remember the nasty incident that got me filing this report in the first place. I'll look at the patch more closely when I get a chance, but the immediate comment I'd make is it's worth adding a sentence saying explicitly to use wbits=-15 if you need to interoperate with some other libraries like PHP, that strip off the header. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue5784 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue7153] add start arg to max and min functions
paul rubin p...@users.sourceforge.net added the comment: 1. Yes, the idea is to figure out the best solution and go with it (or decide to do nothing). That many possibilities exist just points to the need for experience and wisdom in identifying the best choice (one and preferably only one). One of the attractive points about Python is it comes with so many such decisions already wisely made. The design wisdom embodied in Python is almost like a useful software library in its own right. So the presence of multiple choices should be seen as an invitation to resolve the issue, not a flag to keep it unresolved. 2. I agree that the multi-arg and iterator API's should have been done as separate functions (or denoted through a keyword arg), but what we have isn't too bad, and it's what we have. 3. min(iterable, key=f, start=x) should obviously default to the same thing as min([x], key=f). min(*args, start=x) should only be allowed when len(args)==1, since the start arg is restricted to the case of minimum over an iterator. min(start=x) should not be allowed. 4. I'm in general unpersuaded by the argument that a stdlib function isn't worth having because the same thing can be done by bloating up the user code. Python code should be concise, which means using the stdlib in preference to writing more user-defined functions that the next maintainer has to figure out, and which may have their own bugs and unhandled edge cases. For stdlib design, it's mostly a matter of deciding whether a construction occurs often enough to write a re-usable function for. In this case it wouldn't have occurred to me to write any of those suggested versions, instead of writing reduce(max, iterator, 0) with an explanatory comment. But even the observation that reduce made me bloat up the comments in the code, rather than the code itself, was enough to get me to suggest adding the initial arg. 5. I don't think it's good to rely on bool(seq) or len(seq) to be available if there's a simple construction (like here) that works for arbitrary iterables. It's better to handle the general case. I hadn't even realized til just now that sequence and iterable didn't mean the same thing. 6. Yes, I know it's not common to trap ValueErrors when using max with iterables. I wrote code without such traps myself and then got bitten by unhandled exceptions when some of those iterables turned out to be empty (hence my reduce hack). It wouldn't surprise me if lots more such code out there is similarly buggy. I think it's good to make bug-avoiding mechanisms obvious and convenient. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue7153 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue7153] add start arg to max and min functions
New submission from paul rubin p...@users.sourceforge.net: Lots of times I want to find the largest element of a list or sequence, defaulting to 0 if the list or sequence is empty. max(seq) throws an exception if seq is empty, so I end up using reduce(max, seq, 0). That is a standard functional programming idiom but can be a bit confusing to imperative-style Python programmers. max with multiple args is already overloaded to mean the maximum of the args, so I think it would be a good fix to add a keyword arg to accept an optional initial value: max(seq, start=0). For symmetry, min should accept the same arg. The alternatives to using reduce aren't so attractive. If seq happens to be a list, there might be a temptation to conditionalize on len(seq)==0, but that is poor style since it will break if seq later changes to an arbitrary sequence. And trying to test it by calling .next() and saving the value and/or trapping StopIteration gets awfully messy. -- components: Library (Lib) messages: 94145 nosy: phr severity: normal status: open title: add start arg to max and min functions versions: Python 2.5 ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue7153 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue7153] add start arg to max and min functions
Changes by paul rubin p...@users.sourceforge.net: -- type: - feature request ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue7153 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue7153] add start arg to max and min functions
paul rubin p...@users.sourceforge.net added the comment: David, I'm not on that mailing list so hadn't seen the earlier discussion. I sympathasize with Raymond's YAGNI argument because I'm comfortable with reduce(max,seq,0); but then I remember there was once a movement to remove the reduce function from builtins, which would have broken that idiom. I also understand that not everyone is comfortable with that style. I recently had to hand over some code to another programmer where I had used that idiom, and in the course of adding comments to the code in preparation for the handover, I found myself writing quite a few words about why I'd used reduce that way, so I figured that explicit is better than implicit suggests adding default or initial args to the max function, just like reduce already has (I figure that max on a sequence is a special case of reduce). My proposed python implementation: def mymax(*args, **kwargs): if len(args) 1: return max(*args) if len(args) == 0: raise TypeError, mymax needs at least one positional arg if 'initial' in kwargs: return reduce(max,args[0],kwargs['initial']) return reduce(max,args[0]) -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue7153 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue5784] raw deflate format and zlib module
New submission from paul rubin p...@users.sourceforge.net: The zlib module doesn't support raw deflate format, so it doesn't completely interoperate with php's gzdeflate function and fails to decompress some strings that web browsers can decompress. A workaround is to use a special zlib feature and pass the value -15 as the wbits arg: plaintext = zlib.deflate(compressed_text, wbits=-15) I don't know if it's appropriate to mess with the code, but at minimum I urge that the workaround be mentioned in the docs. We had a tremendous distruption where I work because of a malicious raw-deflated PHP script that we couldn't decompress with Python for analysis. We had to resort to decompressing in a PHP container that (through my slipping up) it proceeded to escape from. Help us Python-Kenobi, save us from PHP ;-) -- messages: 86094 nosy: phr severity: normal status: open title: raw deflate format and zlib module ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue5784 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue5784] raw deflate format and zlib module
Changes by paul rubin p...@users.sourceforge.net: -- components: +Library (Lib) type: - feature request versions: +Python 2.5 ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue5784 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue5784] raw deflate format and zlib module
paul rubin p...@users.sourceforge.net added the comment: I should have mentioned, the docs do say When wbits is negative, the standard gzip header is suppressed; this is an undocumented feature of the zlib library, used for compatibility with unzipâs compression file format but this wasn't enough at the time to figure out the issue. I suggest adding something like and the 'raw deflate' format supported by PHP and some web browsers. I better see if I can research the exact situation a bit further, for the sake of documenting it accurately, if others here think it's a good idea. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue5784 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue1560032] confusing error msg from random.randint
paul rubin p...@users.sourceforge.net added the comment: Daniel, thanks--I didn't mean to jump on you, so I'm sorry if it came across that way. Maybe I'm a little oversensitized to this issue due to some unrelated incidents with other programs. I'll try to write a more detailed reply and maybe include a patch later (I can't do it right now). Regards Paul -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue1560032 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue1560032] confusing error msg from random.randint
paul rubin p...@users.sourceforge.net added the comment: ajaksu2, I don't understand why you want to close this bug if it isn't fixed. I can accept that it's not the highest priority issue in the world, but it's something that trips up users from time to time, and it ix obviously fixable. Closing bugs like this is demoralizing to those of us who take the trouble to submit them in the hope of helping improve Python. I've noticed that any number of times over the years, and recently saw a post about Ubuntu bug triage that expressed the sentiment better than I could: http://www.chiark.greenend.org.uk/ucgi/~cjwatson/blosxom/2009/03/02 (And while trying to locate that several week old post through web searches, I came across several more like it...). Anyway, the best thing to do with bugs like this is fix them. If there is other work with higher priority, the obvious thing is to just leave the bug open so someone gets around to it sooner or later. Closing the bug without a fix comes across as destructive. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue1560032 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue4123] random.shuffle slow on deque
paul rubin [EMAIL PROTECTED] added the comment: If it's not a bug, it is at least a surprising gotcha that should be documented in the manual. The collections module is described in the library docs as high performance container datatypes but I could not possibly consider the observed behavior to be high performance. ___ Python tracker [EMAIL PROTECTED] http://bugs.python.org/issue4123 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue4123] random.shuffle slow on deque
New submission from paul rubin [EMAIL PROTECTED]: This is observed in Python 2.5.1, I haven't tried any later versions. d = collections.deque(xrange(10)) random.shuffle(d) is quite slow. Increasing the size to 200k, 300k, etc. shows that the runtime increases quadratically or worse. It's much faster to convert the deque to a list, shuffle the list, and make a new deque from the shuffled list. -- components: Library (Lib) messages: 74773 nosy: phr severity: normal status: open title: random.shuffle slow on deque versions: Python 2.5 ___ Python tracker [EMAIL PROTECTED] http://bugs.python.org/issue4123 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue2857] add codec for java modified utf-8
paul rubin [EMAIL PROTECTED] added the comment: Some java applications use it externally. The purpose seems to be to prevent NUL bytes from appearing inside encoded strings which can confuse C libraries that expect NUL's to terminate strings. My immediate application is parsing lucene indexes: http://lucene.apache.org/java/docs/fileformats.html#Chars __ Tracker [EMAIL PROTECTED] http://bugs.python.org/issue2857 __ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue2857] add codec for java modified utf-8
paul rubin [EMAIL PROTECTED] added the comment: Also, according to wikipedia, tcl also uses that encoding. __ Tracker [EMAIL PROTECTED] http://bugs.python.org/issue2857 __ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue2857] add codec for java modified utf-8
paul rubin [EMAIL PROTECTED] added the comment: I'm not sure what you mean by ditto for Lucene indexes. I wasn't planning to use C code. I was hoping to write Python code to parse those indexes, then found they use this weird encoding, and Python's codec set is fairly inclusive already, so this codec sounded like a reasonably useful addition. It probably shows up other places as well. It might even be a reasonable internal representation for Python, which as I understand it currently can't represent codepoints outside the BMP. Also, it is used in Java serialization, which I think of as a somewhat weird and whacky thing, but it's conceivable that somebody someday might want to write a Python program that speaks the Java serialization protocol (I don't have a good sense of whether that's feasible). Writing an application specific codec with the C API is doable in principle, but it seems like an awful lot of effort for just one quickie program. These indexes are very large and so writing the codec in Python would probably be painfully slow. __ Tracker [EMAIL PROTECTED] http://bugs.python.org/issue2857 __ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue2857] add coded for java modified utf-8
New submission from paul rubin [EMAIL PROTECTED]: For object serialization and some other purposes, Java encodes unicode strings with a modified version of utf-8: http://en.wikipedia.org/wiki/UTF-8#Java http://java.sun.com/javase/6/docs/api/java/io/DataInput.html#modified-utf-8 It is used in Lucene index files among other places. It would be useful if Python had a codec for this, maybe called UTF-8J or something like that. -- components: Library (Lib) messages: 66843 nosy: phr severity: normal status: open title: add coded for java modified utf-8 versions: Python 2.5 __ Tracker [EMAIL PROTECTED] http://bugs.python.org/issue2857 __ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue2138] Add a factorial function
paul rubin [EMAIL PROTECTED] added the comment: Rather than factorial how about a product function, so factorial(n) = product(xrange(1,n+1)). I do like the idea of an imath module whether or not it has factorial, and the topic of this rfe has drifted somewhat towards the desirability of such a module, which is a reasonable question for discussion. I'm more or less indifferent to whether imath has factorial in it or not. I do think it would be useful for it to have functions for things like binomial coefficients that were implemented a little more cleverly than with large factorials, but in this case factorial should be there too. __ Tracker [EMAIL PROTECTED] http://bugs.python.org/issue2138 __ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue2151] no way to get http result status from urllib
New submission from paul rubin: I don't see any way in the docs to get the status of an http request, in particular I want to know whether it's a 404. It does show up in the guts of the library so maybe I can extract it somehow, but there should be a simple documented way. Also, the urllib doc says the info() method returns a mimetools.Message instance, but what actually comes back is an httplib.HTTPMessage instance. I guess that's a subclass, but it's confusing. The doc should describe what actually comes back. -- components: Library (Lib) messages: 62613 nosy: phr severity: normal status: open title: no way to get http result status from urllib type: feature request versions: Python 2.5 __ Tracker [EMAIL PROTECTED] http://bugs.python.org/issue2151 __ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue2138] Factorial
paul rubin added the comment: I like the idea of having some integer math functions like this in the stdlib; whether in the math module or elsewhere doesn't matter much. In particular I remember having to implement xgcd on several separate occasions for unrelated applications, each time requiring about the same head scratching as before, and wishing it was in the stdlib so that could be avoided. This type of function is complicated enough to not rattle immediately off the fingertips, but not complicated enough to be worth looking up in a reference book. http://bugs.python.org/issue457066 has some discussion of xgcd and modular inverses. -- nosy: +phr __ Tracker [EMAIL PROTECTED] http://bugs.python.org/issue2138 __ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue1742669] %d format handling for long values
paul rubin added the comment: I would prefer that %d signal an error 100% of the time if you give it a float. It should not accept 42.0. It is for printing integers. -- nosy: +phr _ Tracker [EMAIL PROTECTED] http://bugs.python.org/issue1742669 _ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
