🌐 Mailman 3 August 2020 - Python-list - python.org

Re: How to remove "" from starting of a string if provided by the user
by MRAB Aug. 13, 2020

Aug. 13, 2020

On 2020-08-11 20:43, Dennis Lee Bieber wrote: > On Tue, 11 Aug 2020 14:17:39 -0400, Joel Goldstick > <joel.goldstick(a)gmail.com> declaimed the following: > [snip] > Warning -- it will fail if the input is just a pair of quotes or pair of > apostrophes -- improvement is > >>>> while s and s[0] in ['"', "'"]: > ... if s[0] == s[-1]: > ... s = s[1:-1] > If the 'if' condition is False, then 's' will remain unchanged, and it will loop forever. I would suggest: >>> while s[ : 1] in {'"', "'"} and s[ : 1] == s[-1 : ]: ... s = s[1 : -1]

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How to remove "" from starting of a string if provided by the user
by Ganesh Pal Aug. 13, 2020

Aug. 13, 2020

How to remove " from the starting and ending of a string , before comparison . Here is an example and my solution wtih eval ( I am advised not to use this one) , please suggest an alternative . I am on linux and python 2.7 g1@X1:/tmp$ cat file2.py #!/usr/bin/python # Case 1 - server2 file is "'/fileno_100.txt'" stat={} stat['server1'] = '/fileno_100.txt' stat['server2'] = "'/fileno_100.txt'" if stat['server1'] == eval(stat['server2']): print "OK" # Case 2 - server2 file is '/fileno_100.txt' stat['server2'] = "'/fileno_100.txt'" if stat['server1'] == eval(stat['server2']): print "OK" # Case 3 - server2 file can be in (a) '/fileno_100.txt' or (b) : "'/fileno_100.txt'" format g1@X1:/tmp$ python file2.py OK OK

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Unable to save any files
by Lim Clayton Aug. 12, 2020

Aug. 12, 2020

Hi, I am a relatively new Python User. I recently downloaded Python on my desktop and I am unable to save anything when I use IDLE. I can run codes on the shell without any issue but running anything on the window which requires saving causes nothing to happen. I still get the prompt which says you need to save before the code can be run but nothing happens when I press Ok. I am using Windows 10 and I have tried uninstalling and reinstalling. Any advice? Yours Sincerely, Clay

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Strange namespace issue
by Lele Gaifax Aug. 12, 2020

Aug. 12, 2020

Hi all, today I faced an issue that, although very easy to fix, left me wondering about what causes it. The context is an application that execute small scripts coming from an external source (say, a database). The application first compile the script, then execute it passing it some values: in the script I wrote this morning I used a list comprehension, executing a method of an instance passed in in the local context. The following example illustrates the problem: class Test: def create_value(self, a): return a*2 script = """\ # This works cv = test.create_value x = [] for i in range(3): x.append(cv(i)) print(x) # This does not: NameError: name 'test' is not defined x = [test.create_value(i) for i in range(3)] print(x) # This neither: NameError: name 'cv' is not defined x = [cv(i) for i in range(3)] print(x) """ code = compile(script, 'script', 'exec') exec(code, {}, {'test': Test()}) I must be missing something, as I cannot understand why within the list comprehension the neither the name "test" nor the name "cv" are defined... Thanks in advance for any enlightenment! ciao, lele. -- nickname: Lele Gaifax | Quando vivrò di quello che ho pensato ieri real: Emanuele Gaifas | comincerò ad aver paura di chi mi copia. lele(a)metapensiero.it | -- Fortunato Depero, 1929.

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[RELEASE] Python 3.9.0rc1 is now available
by Łukasz Langa Aug. 11, 2020

Aug. 11, 2020

Python 3.9.0 is *almost* ready. This release, *3.9.0rc1*, is the penultimate release preview. You can get it here: https://www.python.org/downloads/release/python-390rc1/ Entering the release candidate phase, only reviewed code changes which are clear bug fixes are allowed between this release candidate and the final release. The second candidate and the last planned release preview is currently planned for 2020-09-14. Please keep in mind that this is a preview release and its use is *not* recommended for production environments. Calls to action Core developers: all eyes on the docs now * Are all *your* changes properly documented? * Did you notice *other* changes you know of to have insufficient documentation? Community members We *strongly encourage* maintainers of third-party Python projects to prepare their projects for 3.9 compatibility during this phase. As always, report any issues to the Python bug tracker <https://bugs.python.org/>. Installer news This is the first version of Python to default to the 64-bit installer on Windows. The installer now also actively disallows installation on Windows 7. Python 3.9 is incompatible with this unsupported version of Windows. Major new features of the 3.9 series, compared to 3.8 Some of the new major new features and changes in Python 3.9 are: * PEP 584 <https://www.python.org/dev/peps/pep-0584/>, Union Operators in `dict` * PEP 585 <https://www.python.org/dev/peps/pep-0585/>, Type Hinting Generics In Standard Collections * PEP 593 <https://www.python.org/dev/peps/pep-0593/>, Flexible function and variable annotations * PEP 602 <https://www.python.org/dev/peps/pep-0602/>, Python adopts a stable annual release cadence * PEP 615 <https://www.python.org/dev/peps/pep-0615/>, Support for the IANA Time Zone Database in the Standard Library * PEP 616 <https://www.python.org/dev/peps/pep-0616/>, String methods to remove prefixes and suffixes * PEP 617 <https://www.python.org/dev/peps/pep-0617/>, New PEG parser for CPython * BPO 38379 <https://bugs.python.org/issue38379>, garbage collection does not block on resurrected objects; * BPO 38692 <https://bugs.python.org/issue38692>, os.pidfd_open added that allows process management without races and signals; * BPO 39926 <https://bugs.python.org/issue39926>, Unicode support updated to version 13.0.0; * BPO 1635741 <https://bugs.python.org/issue1635741>, when Python is initialized multiple times in the same process, it does not leak memory anymore; * A number of Python builtins (range, tuple, set, frozenset, list, dict) are now sped up using PEP 590 <https://www.python.org/dev/peps/pep-0590> vectorcall; * A number of Python modules (_abc, audioop, _bz2, _codecs, _contextvars, _crypt, _functools, _json, _locale, operator, resource, time, _weakref) now use multiphase initialization as defined by PEP 489 <https://www.python.org/dev/peps/pep-0489/>; * A number of standard library modules (audioop, ast, grp, _hashlib, pwd, _posixsubprocess, random, select, struct, termios, zlib) are now using the stable ABI defined by PEP 384 <https://www.python.org/dev/peps/pep-0384/>.

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IDLE: New Feature?
by Steve Aug. 11, 2020

Aug. 11, 2020

Where would the conversation have to happen to get the forces-that-be to install a pull-down/history menu for the Find option in IDLE? To have to retype the search option over and over when I am toggling between two or more searches gets tiresome. I would rather spend my brain cells and bandwidth thinking about coding. Steve ---------------------------------------------------------------------------- ---------------- Footnote: There's 99 bugs in the code, in the code. 99 bugs in the code. Take one down and patch it all around. Now there's 117 bugs in the code.

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How explain why Python is easier/nicer than Lisp which has a simpler grammar/syntax?
by Christian Seberino Aug. 11, 2020

Aug. 11, 2020

Python is my favorite language and the easiest to use in my opinion. Lisp has a far simpler grammar and syntax. A beginner I think could learn Lisp much faster than Python. Therefore, it seems like Lisp *should* be easier to work with and more readable. I don't feel like it is easier to use but I can't see *why* that is. My best guess..... Lisp pros: simpler syntax Lisp cons: prefix notation, lots more parentheses My hypothesis is that the cons slightly outweigh the pros of Lisp which is why Python is easier to work with and is more readable in the end? chris

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Any timeline for PIL for Python 3.4
by Martin Aug. 11, 2020

Aug. 11, 2020

Hi, I am running Python 3.4.4, and would like to use the Python Imaging Library (PIL). This is currently not available for Python Version 3. Does anybody know when it will become available? Plan B is to install Python 2.7.18. I just need an idea of how long I would need to wait for Plan A. -- Regards, Martin Leese E-mail: please(a)see.Web.for.e-mail.INVALID Web: http://members.tripod.com/martin_leese/

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Re: Any timeline for PIL for Python 3.4
by jfong＠ms4.hinet.net Aug. 11, 2020

Aug. 11, 2020

dn於 2020年8月11日星期二 UTC+8下午1時29分47秒寫道： > On 11/08/2020 16:35, Martin wrote: > > I am running Python 3.4.4, and would like to > > use the Python Imaging Library (PIL). This > > is currently not available for Python > > Version 3. Does anybody know when it will > > become available? > > > > Plan B is to install Python 2.7.18. I just > > need an idea of how long I would need to > > wait for Plan A. > > > 1 PIL was discontinued about a decade back. Please use "Pillow" (a fork > - note first three letters), which is available from PyPI (pip3) > > 2 Bad news though, IIRC it requires Python 3.5+ > > 3 Don't degrade to Py2 if you can at all avoid doing-so! > -- > Regards =dn Pillow for Python 3.4 can be downloaded at this moment in time:-) https://www.lfd.uci.edu/~gohlke/pythonlibs/#pillow --Jach

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importlib: import X as Y; from A import B
by Jason Friedman Aug. 11, 2020

Aug. 11, 2020

I have some code I'm going to share with my team, many of whom are not yet familiar with Python. They may not have 3rd-party libraries such as pandas or selenium installed. Yes I can instruct them how to install, but the path of least resistance is to have my code to check for missing dependencies and attempt to install for them. This code works as desired: import importlib import subprocess PIP_EXE = "/opt/python/bin/pip3" for module_name in ("module1", "module2", "module3"): try: importlib.import_module(module_name) except ModuleNotFoundError: install_command = f"{PIP_EXE} install {module_name}" status, output = subprocess.getstatusoutput(install_command) if not status: importlib.import_module(module_name) print(f"Successfully installed {module_name}.") else: print(f"Error when attempting to install {module_name}: {output}") The cherry-on-top would be to import with the "aliasing" and "from" they will most likely see on the web, so that my code matches what they see there. In other words, instead of: import pandas df = pandas.from_csv (...) import selenium browser = selenium.webdriver.Firefox() on the web they will typically see: import pandas as pd df = pd.from_csv (...) from selenium import webdriver browser = webdriver.Firefox() I don't see anything in the importlib module documentation that supports this.

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