python

About

This is a collection of a various Python scripts and helper information.

Scripts

• scripts
  • Script to create virtualenv from requirements.txt
  • Script to start and use virtualenv
• helpers
  • cmdUninstallGlobalPackages.bat helps to uninstall globally installed pacakges

Global dependencides

Virtual environments are highly recommended for Python development and must be used by default. However, in certain cases, it's beneficial to install some Python packages globally:

• Extremely fast Python package installer and resolver

   pip install --upgrade uv

• Multi-language pre-commit hooks for Git

   pip install --upgrade pre-commit

Scripts Collection and Subfolders

Located in subdirectory snippets

• urls_availability_in_markdown.py
  • Downloads markdown files and checks, if provided URLS are accessible
• jupyter_notebook_config_post_save.py
  • Jupyter helpers
• pyparser_gist_comments.py
  • Parser that fetches comments from GitHub Gist
• deprecated
  • helper_directory.py
    • Useful functions wrapper for working with files and directories

One Liners

• Random password generators

python-c"from random import choice; import uuid; print ('{0}{1}{2}'.format(''.join([choice('abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789') for i in range(8)]), str(uuid.uuid4().get_hex().upper()[0:6]), ''.join([choice('%^*(-_=+)') for i in range(2)])))"

python-c"from random import choice; import uuid; print ('{0}'.format(''.join([choice('abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789') for i in range(10)])))"

• Current date of the week

python-c"import datetime; print('week of the year {0}'.format(datetime.date.today().isocalendar()[1]))"

• Various Python Paths

python-c"import sys; print ('\n'.join(sys.path))"

python3-c"import sys; print ('\n'.join(sys.path))"

• Check if virtual environment is active

python -c "import sys; print('virtualenv is active' if sys.prefix != sys.base_prefix else 'virtualenv is NOT active')"

Starting Simple Python Web Server

• Python 2

python -m SimpleHTTPServer 80

• Python 3

python -m http.server 5151 --bind 127.0.0.1

Format JSON in command line

• Formatting json

python -m json.tool myfile.json

• OR

python3 -m json.tool myfile.json

Date

fromdatetimeimportdatetimenow=datetime.now().strftime("%Y-%m-%d %H:%M:%S")
# ornow=datetime.now().strftime("%Y-%m-%d %H:%M[:%S[.%f]]")

Disable bytecode

On Linux

export PYTHONDONTWRITEBYTECODE=1

On Windows

set PYTHONDONTWRITEBYTECODE=1

importsyssys.dont_write_bytecode=True

Exceptions

• Simple implementation

importtracebacktry:
print ('[i] Exception handling that shows the line with exception')
raiseException('Test')
exceptException:
print (traceback.format_exc())

• Further implementation

deflog_traceback(ex, ex_traceback=None):
''' Logs exceptions'''ifex_tracebackisNone: ex_traceback=ex.__traceback__tb_lines= [ line.rstrip('\n') forlineintraceback.format_exception(ex.__class__, ex, ex_traceback)]
#logging.exception(tb_lines)print(tb_lines)
try:
raiseException('A test exception')
exceptExceptionasex:
_, _, ex_traceback=sys.exc_info()
log_traceback(ex, ex_traceback)

Object Helpers

defdump(obj):
""" Makes dump of the object (helper function)"""forattrindir(obj):
print('obj.{0} = {1}'.format(attr, getattr(obj, attr)))

VS Code + Python

• https://github.com/vdmitriyev/sourcecodesnippets/blob/master/vs-code/README.md

pip improvements

• Disable pip outside of a virtual environment. Further info here

pip config set global.require-virtualenv True

• Materials
  • https://unix.stackexchange.com/questions/492041/is-there-a-way-to-disable-pip-outside-of-a-virtual-environment

Python Code Quality

• pre-commit
  • Install

    pip install --upgrade pre-commit
    

  • View sample config

    pre-commit sample-config
    

  • Create empty config file and copt sample config (pre-commit sample-config)

    touch .pre-commit-config.yaml
    

  • Install the git hook scripts:

    pre-commit install
    

  • Run manually:

    pre-commit run --all-files
    

  • Bypass pre-commit hooks in git

    git commit -m "will fix asap" --no-verify

  • Add further plugins
    • Overview
      • https://pre-commit.com/hooks.html
    • Plugins
      • https://github.com/psf/black
      • https://github.com/pypa/pip-audit
        • Runs slow
• pre-commit wroking example:
  • https://github.com/vdmitriyev/pymultissher/blob/main/.pre-commit-config.yaml
  • pre-commit by default places its repository store in ~/.cache/pre-commit
• isort
  • https://github.com/pycqa/isort
  • VS Code Extension + Config
    • https://marketplace.visualstudio.com/items?itemName=ms-python.isort
• Black Formatter
  • https://marketplace.visualstudio.com/items?itemName=ms-python.black-formatter
• Materials
  • Boring Python: code quality
  • How to Set Up Pre-Commit Hooks

Global .gitignore (.gitignore_global)

• https://gist.github.com/subfuzion/db7f57fff2fb6998a16c
• Create a new file %USERPROFILE%\.gitignore_global
• Add what you want to ignore globally in git
• Config git to find global gitignore file:

  git config --global core.excludesfile "%USERPROFILE%\.gitignore_global"
  

• Verify by checking file %USERPROFILE%\.gitconfig

  cat %USERPROFILE%\.gitconfig
  

Author

• Viktor Dmitriyev