🇺🇦 Python Programming Сhallenges

Forwarded from oleg_log (Oleg Kovalov)

"filter(P, S) is almost always written clearer as [x for x in S if P(x)]"

(с) Guido van Rossum on Python

545 views08:37

A tool (and pre-commit hook) to automatically add trailing commas to calls and literals.
tl;dr:

 # with no trailing commas
 x(
-    arg
+    arg,
+    arg2
 )

 # with trailing commas
 x(
     arg,
+    arg2,
 )

https://github.com/asottile/add-trailing-comma

GitHub

GitHub - asottile/add-trailing-comma: A tool (and pre-commit hook) to automatically add trailing commas to calls and literals.

A tool (and pre-commit hook) to automatically add trailing commas to calls and literals. - asottile/add-trailing-comma

914 views22:08

🇺🇦 Python Programming Сhallenges

После моего доклада на python fwdays обещал рассказать как пользоваться tcpdump:

Andrii Soldatenko, [18.05.20 13:15]
tcpdump example:
1. Я запустил postgresql в докере и пробросли порт в систему (5432)
f9284723a810 postgres "docker-entrypoint.s…" 2 days ago Up 2 days 0.0.0.0:5432->5432
2. запускаем tcpdump:

sudo tcpdump -i lo0 -nX dst port 5432

важный параметр:
-X print data of each packet in hex and ascii

3. Логинимся

PGPASSWORD=postgres psql -U postgres -h localhost

4. То что видим в tcpdump output (некоторые пакеты я пропустил):

13:09:25.020387 IP6 ::1.62337 > ::1.5432: Flags [P.], seq 8:92, ack 2, win 6371, options [nop,nop,TS val 962074756 ecr 962074756], length 84
        0x0000:  6004 334d 0074 0640 0000 0000 0000 0000  `.3M.t.@........
        0x0010:  0000 0000 0000 0001 0000 0000 0000 0000  ................
        0x0020:  0000 0000 0000 0001 f381 1538 3b74 c631  ...........8;t.1
        0x0030:  b72a e9e7 8018 18e3 007c 0000 0101 080a  .*.......|......
        0x0040:  3958 1884 3958 1884 0000 0054 0003 0000  9X..9X.....T....
        0x0050:  7573 6572 0070 6f73 7467 7265 7300 6461  user.postgres.da
        0x0060:  7461 6261 7365 0070 6f73 7467 7265 7300  tabase.postgres.
        0x0070:  6170 706c 6963 6174 696f 6e5f 6e61 6d65  application_name
        0x0080:  0070 7371 6c00 636c 6965 6e74 5f65 6e63  .psql.client_enc
        0x0090:  6f64 696e 6700 5554 4638 0000            oding.UTF8..
1

13:09:25.022436 IP6 ::1.62337 > ::1.5432: Flags [P.], seq 92:133, ack 15, win 6371, options [nop,nop,TS val 962074758 ecr 962074758], length 41
        0x0000:  6004 334d 0049 0640 0000 0000 0000 0000  `.3M.I.@........
        0x0010:  0000 0000 0000 0001 0000 0000 0000 0000  ................
        0x0020:  0000 0000 0000 0001 f381 1538 3b74 c685  ...........8;t..
        0x0030:  b72a e9f4 8018 18e3 0051 0000 0101 080a  .*.......Q......
        0x0040:  3958 1886 3958 1886 7000 0000 286d 6435  9X..9X..p...(md5
        0x0050:  6234 3339 6532 3464 3065 6231 3861 3635  b439e24d0eb18a65
        0x0060:  6431 6563 3039 6438 3231 3333 3665 6565  d1ec09d821336eee
        0x0070:  00                                       .
1

Далее все завист от того как настроен ваш сервер БД (https://www.postgresql.org/docs/9.1/auth-pg-hba-conf.html)
у меня это md5 - Require the client to supply an MD5-encrypted password for authentication. See Section 19.3.2 for details.

13:09:25.022436 IP6 ::1.62337 > ::1.5432: Flags [P.], seq 92:133, ack 15, win 6371, options [nop,nop,TS val 962074758 ecr 962074758], length 41
        0x0000:  6004 334d 0049 0640 0000 0000 0000 0000  `.3M.I.@........
        0x0010:  0000 0000 0000 0001 0000 0000 0000 0000  ................
        0x0020:  0000 0000 0000 0001 f381 1538 3b74 c685  ...........8;t..
        0x0030:  b72a e9f4 8018 18e3 0051 0000 0101 080a  .*.......Q......
        0x0040:  3958 1886 3958 1886 7000 0000 286d 6435  9X..9X..p...(md5
        0x0050:  6234 3339 6532 3464 3065 6231 3861 3635  b439e24d0eb18a65
        0x0060:  6431 6563 3039 6438 3231 3333 3665 6565  d1ec09d821336eee
        0x0070:  00                                       .
1

но бывает там стоит password - Require the client to supply an unencrypted password for authentication =)

1.0K viewsedited 09:39

🇺🇦 Python Programming Сhallenges

Import Linter allows you to define and enforce rules for the imports within and between Python packages.

[importlinter]
root_package = myproject

[importlinter:contract:1]
name=Foo doesn't import bar or baz
type=forbidden
source_modules=
    myproject.foo
forbidden_modules=
    myproject.bar
    myproject.baz

Example output:

=============
Import Linter
=============

---------
Contracts
---------

Analyzed 23 files, 44 dependencies.
-----------------------------------

Foo doesn't import bar or baz BROKEN

Contracts: 1 broken.

https://import-linter.readthedocs.io/en/stable/readme.html

1.1K views19:45

🇺🇦 Python Programming Сhallenges

beta preview of Python 3.9 is out:

- PEP 584, Union Operators in dict
- PEP 585, Type Hinting Generics In Standard Collections
- PEP 593, Flexible function and variable annotations
- PEP 602, Python adopts a stable annual release cadence
- PEP 615, Support for the IANA Time Zone Database in the Standard Library
- PEP 616, String methods to remove prefixes and suffixes
- PEP 617, New PEG parser for CPython

https://www.python.org/downloads/release/python-390b2/

Python.org

Python Release Python 3.9.0b2

The official home of the Python Programming Language

1.1K views09:53

🇺🇦 Python Programming Сhallenges

Restructuring data, the Python way.

>>> import glom
>>> glom.assign({}, "a.b.c.d", 42, missing=dict)
{'a': {'b': {'c': {'d': 42}}}}

# Path-based access for nested structures
>>> target = {'a': {'b': {'c': 'd'}}}
>>> glom(target, 'a.b.c') 
'd'

happy glomming! 😋

https://glom.readthedocs.io/en/latest/

1.2K views13:34

🇺🇦 Python Programming Сhallenges

Forwarded from Sysadmin Tools 🇺🇦

https://youtu.be/8S8zwJBOD0w

YouTube

Dive into BPF performance tools using python [ru] / Андрей Солдатенко

Видео с онлайн-конференции Python fwdays'20, которая прошла 16 мая 2020 года.

Описание доклада:
Этот доклад — быстрое ознакомления с BPF и различными инструментами python. Это сессия live coding, где Андрей демонстрирует, как реализовать, использовать…

763 views21:27

🇺🇦 Python Programming Сhallenges

Forwarded from 🇺🇦 Go for two :)

Note #68: The Rules of Optimization Club

1. You do not optimize.
2. You do not optimize, without measuring first.
3. When the performance is not bound by the code, but by external factors, the optimization is over.
4. Only optimize code that already has full unit test coverage.
5. One factor at a time.
6. No unresolved bugs, no schedule pressure.
7. Testing will go on as long as it has to.
8. If this is your first night at Optimization Club, you have to write a test case.

from https://wiki.c2.com/?RulesOfOptimizationClub

857 views13:04

🇺🇦 Python Programming Сhallenges

PEP 622 -- Structural Pattern Matching

Interesting proposal for python 3.10.

The proposed indentation structure is as following:

match some_expression:
    case pattern_1:
        ...
    case pattern_2:
        ...

and example from pep:

match number:
    case 0:
        print("Nothing")
    case 1:
        print("Just one")
    case 2:
        print("A couple")
    case -1:
        print("One less than nothing")
    case 1-1j:
        print("Good luck with that...")

https://www.python.org/dev/peps/pep-0622/

Python Enhancement Proposals (PEPs)

PEP 622 – Structural Pattern Matching | peps.python.org

This PEP proposes to add a pattern matching statement to Python, inspired by similar syntax found in Scala, Erlang, and other languages.

1.5K views21:46

🇺🇦 Python Programming Сhallenges

Asynchronous IO Support for Core and ORM

SQLAlchemy 1.4 now supports Python asyncio-compatible database drivers using an all-new asyncio front-end interface to Connection for Core usage as well as Session for ORM use, using the AsyncConnection and AsyncSession objects.

https://docs.sqlalchemy.org/en/14/changelog/migration_14.html#asynchronous-io-support-for-core-and-orm

1.4K views12:16

🇺🇦 Python Programming Сhallenges

Forwarded from 🇺🇦 Go for two :)

Note #71 The seven rules of a great Git commit message

1. Separate subject from body with a blank line
2. Limit the subject line to 50 characters
3. Capitalize the subject line
4. Do not end the subject line with a period
5. Use the imperative mood in the subject line
6. Wrap the body at 72 characters
7. Use the body to explain what and why vs. how

https://chris.beams.io/posts/git-commit/

1.5K views20:00

🇺🇦 Python Programming Сhallenges

Python 3.9 is around the corner

https://lwn.net/SubscriberLink/831783/8afbf1812decf4d9/

lwn.net

Python 3.9 is around the corner

Python
3.9.0rc2 was released on September 17, with the final version scheduled
for October 5, roughly a year after the release of Python 3.8. Python 3.9
will come with new operators for dictionary unions, a new parser, two string
operations meant…

1.5K views14:09

🇺🇦 Python Programming Сhallenges

Hypermodern Python 👩‍🚀 🐍

Chapter 1: Setup
Chapter 2: Testing
Chapter 3: Linting
Chapter 4: Typing
Chapter 5: Documentation
Chapter 6: CI/CD

https://cjolowicz.github.io/posts/hypermodern-python-01-setup/

1.6K views22:24

🇺🇦 Python Programming Сhallenges

Airflow 2.0 ->

https://www.astronomer.io/blog/introducing-airflow-2-0/

1.5K views22:20

🇺🇦 Python Programming Сhallenges

Releasing pip 20.3, featuring new dependency resolver

https://pyfound.blogspot.com/2020/11/pip-20-3-new-resolver.html

Python Software Foundation Blog

Releasing pip 20.3, featuring new dependency resolver

On behalf of the Python Packaging Authority and the pip team, I am pleased to announce that we have just released pip 20.3 , a new versio...

1.4K views17:37

🇺🇦 Python Programming Сhallenges

Interesting thread how to solve interview problem https://twitter.com/al_grigor/status/1357028887209902088?s=21

Twitter

Alexey Grigorev

Most candidates cannot solve this interview problem: 🔸 Input: "aaaabbbcca" 🔸 Output: [("a", 4), ("b", 3), ("c", 2), ("a", 1)] Write a function that converts the input to the output I ask it in the screening interview and give it 25 minutes How would you solve…

1.1K views17:46

🇺🇦 Python Programming Сhallenges

Armin dislikes new PEP regarding structural pattern matching https://twitter.com/mitsuhiko/status/1359263135304187910
btw PEP has been approved!

https://www.python.org/dev/peps/pep-0636/

Twitter

Armin Ronacher

I really, really, really don't want to be dismissive of all the new python language features but it's hard not to see faults in PEPs like this: https://t.co/fIvSTSEcxl — pattern matching is awesome, but only when the language is built for it.

1.2K views22:40

🇺🇦 Python Programming Сhallenges

I can't recall where I saw this originally, but you can use the spaceship operator "--0--" to turn floor division into ceiling division:

>>> 12//5
2
>>> --0-- 12//5
3

There's also the ++0++ operator when you want to emphasize that you really *do* mean floor division:

>>> ++0++ 12//5
2

from https://bugs.python.org/issue43255#msg387248
But yes, -(-n // d) is the easy (if a little bit cryptic) way to get the ceiling of n / d.

1.2K views19:19

🇺🇦 Python Programming Сhallenges

It's just a trick

It's because unary minus is right-associative and binds tighter than binary minus which is left-associative

-12 // 5 => - 3
- (-12 // 5) => +3
The rest is just putting 0 at the start:
--0 == 0
and --0--12//5 is parsed as
-(-(0)) - (- (12 // 5))

from Twitter https://twitter.com/ericpromislow/status/1362475189125095425?s=21

Twitter

ericpromislow

@professorcraven @VictorStinner @nedbat It's just a trick It's because unary minus is right-associative and binds tighter than binary minus which is left-associative -12 // 5 => - 3 - (-12 // 5) => +3 The rest is just putting 0 at the start: --0 == 0 and…

1.4K views23:08