Python Table Manners: Cut the Cookie Gracefully @ Kaohsiung.py

3e049ed33195d00a8b745b16c63dce6e?s=47 Lee Wei
August 31, 2020

Python Table Manners: Cut the Cookie Gracefully @ Kaohsiung.py

3e049ed33195d00a8b745b16c63dce6e?s=128

Lee Wei

August 31, 2020
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  1. @clleew Python Table Manners: Cut the Cookie Gracefully A Guideline

    Toward Cleaner Code
  2. @clleew Outline • Clean up the table - Dependency Management

    • Put the correct tablewares - Testing • Use the tablewares elegantly - Coding Style • Mnemonic phrase - Task management • Say please! - Check before git operation • Speak formally - Cultivate a git commit convention • Safety matters - Security Issues • Where's the Cookie? - Project template
  3. @clleew __name__ = 李唯 / Wei Lee __position__ = [

    Software Engineer @ Rakuten Slice, Volunteer @ PyCon Taiwan, "Maintainer of commitizen-tools, ] __twitter__ = @clleew __github__ = Lee-W __blog__ = http://lee-w.github.io • $ cat speaker.py
  4. @clleew $ python speaker.py File "speaker.py", line 1 __name__ =

    李唯 / Wei Lee ^ SyntaxError: invalid syntax $ python speaker.py
  5. @clleew Dependency Management Clean up the table

  6. @clleew How we used to start a Python project

  7. @clleew Sometimes we just forgot to… • ... activate /

    deactivate virtual environment • ... add package into requirements.txt
  8. @clleew Pipenv Python Dev Workflow for Humans • manage virtual

    environment + package → update at once → No more manual sync up! • generate hashes from packages → ensure getting the same packages next time
  9. @clleew Initial Virtual Environment

  10. @clleew Empty Pipfile [[source]] name = "pypi" url = "https://pypi.org/simple"

    verify_ssl = true [dev-packages] [packages] [requires] python_version = "3.7"
  11. @clleew Install Package

  12. @clleew Pipfile with “requests” [[source]] name = "pypi" url =

    "https://pypi.org/simple" verify_ssl = true [dev-packages] [packages] requests = "*" [requires] python_version = "3.7" [packages] requests = "*"
  13. @clleew "requests": { "hashes": [ "sha256:11e007a8a2aa0323f5a921e9e6a2d7e4e67d9877e85773fba9ba6419025cbeb4", "sha256:9cf5292fcd0f598c671cfc1e0d7d1a7f13bb8085e9a590f48c010551dc6c4b31" ], "index": "pypi",

    "version": "==2.22.0" }, { ...... "default": { ...... "requests": { "hashes": [ "sha256:11e007a8a2aa0323f5a921e9e6a2d7e4e67d9877e85773fba9ba6419025cbeb4", "sha256:9cf5292fcd0f598c671cfc1e0d7d1a7f13bb8085e9a590f48c010551dc6c4b31" ], "index": "pypi", "version": "==2.22.0" }, "urllib3": { "hashes": [ "sha256:3de946ffbed6e6746608990594d08faac602528ac7015ac28d33cee6a45b7398", "sha256:9a107b99a5393caf59c7aa3c1249c16e6879447533d0887f4336dde834c7be86" ], "version": "==1.25.6" } }, ...... } Pipfile.lock with “requests”
  14. @clleew "requests": { "hashes": [ "sha256:11e007a8a2aa0323f5a921e9e6a2d7e4e67d9877e85773fba9ba6419025cbeb4", "sha256:9cf5292fcd0f598c671cfc1e0d7d1a7f13bb8085e9a590f48c010551dc6c4b31" ], "index": "pypi",

    "version": "==2.22.0" }, { ...... "default": { ...... "requests": { "hashes": [ "sha256:11e007a8a2aa0323f5a921e9e6a2d7e4e67d9877e85773fba9ba6419025cbeb4", "sha256:9cf5292fcd0f598c671cfc1e0d7d1a7f13bb8085e9a590f48c010551dc6c4b31" ], "index": "pypi", "version": "==2.22.0" }, "urllib3": { "hashes": [ "sha256:3de946ffbed6e6746608990594d08faac602528ac7015ac28d33cee6a45b7398", "sha256:9a107b99a5393caf59c7aa3c1249c16e6879447533d0887f4336dde834c7be86" ], "version": "==1.25.6" } }, ...... } Pipfile.lock with “requests” You’re guaranteed to install the exact same package next time.
  15. @clleew

  16. @clleew Install package only in dev

  17. @clleew Pipfile with “pytest" [[source]] name = "pypi" url =

    "https://pypi.org/simple" verify_ssl = true [dev-packages] pytest = "*" [packages] requests = "*" [requires] python_version = "3.7" [dev-packages] pytest = "*"
  18. @clleew Run in virtual environment

  19. @clleew Some people might say that pipenv ... • ...

    does not update frequently. • ... locks slowly. • ... does not syncs up with install_requires in setup.py
  20. @clleew Poetry

  21. @clleew Poetry commands

  22. @clleew Testing Put the correct tablewares

  23. @clleew unittest Unit testing framework in Python Standard Library

  24. @clleew pytest

  25. @clleew Why pytest • More Pythonic • Compatible with old

    unittest tests • No more assert.+ (e.g., assertEqual, assertTrue, etc.)
 → just assert • Better test discovery • Advance features: mark, parameterize, etc. • Plenty of plugins
  26. @clleew Run pytest

  27. @clleew Run pytest

  28. @clleew always run python inside a virtual environment

  29. @clleew unittest style tests import unittest from atta.partner import sponsor

    class TestSponsor(unittest.TestCase): def setUp(self): sponsors = sponsor.get_all_sponsors('./data/packages.yaml', './data/sponsors.yaml') self.sponsors = sponsors ...... def test_sponsor_number(self): self.assertEqual(len(self.sponsors), 1) .......
  30. @clleew unittest style tests import unittest from atta.partner import sponsor

    class TestSponsor(unittest.TestCase): def setUp(self): sponsors = sponsor.get_all_sponsors('./data/packages.yaml', './data/sponsors.yaml') self.sponsors = sponsors ...... def test_sponsor_number(self): self.assertEqual(len(self.sponsors), 1) ....... Prepare all the data needed in test cases
  31. @clleew unittest style tests import unittest from atta.partner import sponsor

    class TestSponsor(unittest.TestCase): def setUp(self): sponsors = sponsor.get_all_sponsors('./data/packages.yaml', './data/sponsors.yaml') self.sponsors = sponsors ...... def test_sponsor_number(self): self.assertEqual(len(self.sponsors), 1) .......
  32. @clleew unittest style tests import unittest from atta.partner import sponsor

    class TestSponsor(unittest.TestCase): def setUp(self): sponsors = sponsor.get_all_sponsors('./data/packages.yaml', './data/sponsors.yaml') self.sponsors = sponsors ...... def test_sponsor_number(self): self.assertEqual(len(self.sponsors), 1) .......
  33. @clleew pytest style tests import pytest from report_generator.partner import sponsor

    class TestSponsor: @pytest.fixture(scope="class") def sponsors(self): return sponsor.get_all_sponsors("test/data/packages.yaml", “test/data/sponsors.yaml") ...... def test_sponsor_number(self, sponsors): assert len(sponsors) == 1 ......
  34. @clleew pytest style tests import pytest from report_generator.partner import sponsor

    class TestSponsor: @pytest.fixture(scope="class") def sponsors(self): return sponsor.get_all_sponsors("test/data/packages.yaml", “test/data/sponsors.yaml") ...... def test_sponsor_number(self, sponsors): assert len(sponsors) == 1 ...... Prepare the data needed in separate fixtures
  35. @clleew pytest style tests import pytest from report_generator.partner import sponsor

    class TestSponsor: @pytest.fixture(scope="class") def sponsors(self): return sponsor.get_all_sponsors("test/data/packages.yaml", “test/data/sponsors.yaml") ...... def test_sponsor_number(self, sponsors): assert len(sponsors) == 1 ......
  36. @clleew pytest style tests import pytest from report_generator.partner import sponsor

    @pytest.fixture(scope="function") def sponsors(): return sponsor.get_all_sponsors("test/data/packages.yaml", "test/data/sponsors.yaml") def test_sponsor_number(sponsors): assert len(sponsors) == 1
  37. @clleew pytest style tests import pytest from report_generator.partner import sponsor

    @pytest.fixture(scope="function") def sponsors(): return sponsor.get_all_sponsors("test/data/packages.yaml", "test/data/sponsors.yaml") def test_sponsor_number(sponsors): assert len(sponsors) == 1
  38. @clleew Configuration - pytest.ini [pytest] addopts = --strict-markers norecursedirs =

    .* build dist CVS _darcs {arch} *.egg venv env virtualenv Configure through pyproject.toml will be when 6.0 released #7247
  39. @clleew Pytest - powerful plugins • pytest-mock: Replace objects that

    are hard to test with fake objects • pytest-cov: Generate test coverage report • pytest-xdist: Distributed testing • and etc.
  40. @clleew Coding Style Use the tablewares elegantly

  41. @clleew flake8 • Enforcing style consistency across Python project •

    Check possible errors before running your program • Eliminate bad style
  42. @clleew import os os = "My Operating system" Example -

    bad_code.py
  43. @clleew import os os = "My Operating system" redefinition of

    imported library
 (possible error) Example - bad_code.py
  44. @clleew import os os = "My Operating system" additional space


    (bad coding style) redefinition of imported library
 (possible error) Example - bad_code.py
  45. @clleew Run flake8

  46. @clleew Configuration - setup.cfg [flake8] ignore = # F632: use

    ==/!= to compare str, bytes, and int literals F632, # W503: Line break occurred before a binary operator W503, # E501: Line too long E501, # E203: Whitespace before ':' (for black) E203 exclude = .git, __pycache__, build, dist max-line-length = 88
  47. @clleew Pylint

  48. @clleew import os os = "My Operating system" additional space


    (bad coding style) redefinition of imported library
 (possible error) Example - bad_code.py
  49. @clleew Run pylint

  50. @clleew Run pylint with "-r" argument A bunch of reports

    that 
 you can compare 
 with your previous run
  51. Configuration - pyproject.toml [tool.pylint.messages_control] disable = [ "bad-continuation", "missing-function-docstring", "missing-module-docstring",

    "invalid-name" ] [tool.pylint.format] max-line-length = 88
  52. @clleew mypy • Static type checker • Compile-time type checking


    → avoid possible runtime errors • Type annotation enhances readability
 → machine-checked documentation
  53. from typing import List def func(vals: List[str]): for val in

    vals: assert isinstance(val, str) func([1, 2, 3]) Example - error_type.py List[str] [1, 2, 3]
  54. from typing import List def func(vals: List[str]): for val in

    vals: assert isinstance(val, str) func([1, 2, 3]) Example - error_type.py List[str] [1, 2, 3]
  55. Run mypy

  56. Run mypy all the files with .py extension

  57. Run mypy ignore errors that libs that is not type

    annotated
  58. @clleew Configuration - setup.cfg [mypy] files = **/*.py ignore_missing_imports =

    true follow_imports = silent warn_redundant_casts = True warn_unused_ignores = True warn_unused_configs = True [mypy] files = **/*.py ignore_missing_imports = true
  59. @clleew Configuration - setup.cfg [mypy] files = **/*.py ignore_missing_imports =

    true follow_imports = silent warn_redundant_casts = True warn_unused_ignores = True warn_unused_configs = True [mypy] files = **/*.py ignore_missing_imports = true
  60. Run mypy with configuration

  61. @clleew One step forward Fix the style automatically

  62. Black

  63. Run Black

  64. How Black reformat

  65. How Black reformat

  66. Why Black? The black code style is not configurable.

  67. Why Black? The black code style is not configurable. No

    more arguing about which style is better
  68. –The Zen of Python, by Tim Peters “There should be

    one-- and preferably only one --obvious way to do it.”
  69. @clleew Configuration - pyproject.toml [tool.black] line-length = 88 include =

    '\.pyi?$' exclude = ''' /( \.eggs | \.git | \.hg | \.mypy_cache | \.tox | \.venv | _build | buck-out | build | dist )/ '''
  70. Isort

  71. Example wrong_import_order.py import django import os import some_custom_package import flask

    import datetime ...
  72. According to PEP8 • Imports should be grouped in the

    following order: 1. Standard library imports. 2. Related third party imports. 3. Local application/library specific imports. • You should put a blank line between each group of imports.
  73. Run Isort

  74. Run Isort import datetime import os import django import flask

    import some_custom_package ...
  75. @clleew Configuration - pyproject.toml [tool.isort] line_length = 88 multi_line_output =

    3 include_trailing_comma = true force_grid_wrap = 0 use_parentheses = true
  76. Style formatting and linting

  77. None
  78. @clleew Task Management Mnemonic phrase

  79. Invoke • Task execution tool that can manage your commands

    • It’s like a Makefile but in Python.
  80. Invoke in practice (rg-cli)

  81. Before invoke in rg-cli

  82. Before invoke in rg-cli

  83. After invoke in rg-cli

  84. List all commands

  85. How ? - tasks.py from invoke import task VENV_PREFIX =

    "pipenv run" ...... @task def install(cmd): """Install script in pipenv environment""" cmd.run(f"{VENV_PREFIX} python setup.py install")
  86. How ? - tasks.py from invoke import task VENV_PREFIX =

    "pipenv run" ...... @task def install(cmd): """Install script in pipenv environment""" cmd.run(f"{VENV_PREFIX} python setup.py install")
  87. How ? - tasks.py from invoke import task VENV_PREFIX =

    "pipenv run" ...... @task def install(cmd): """Install script in pipenv environment""" cmd.run(f"{VENV_PREFIX} python setup.py install")
  88. Modulize - Namespace

  89. Autocomplete

  90. Autocomplete

  91. Autocomplete

  92. Why not use Makefile? 1.We’re Python developers! 2.Some tasks might

    not be easy to handle through shell script. 3.Combining Python and shell script
  93. @clleew Check before git operation Say please!

  94. @clleew pre-commit • Why? • Sometimes we still forget to

    run the check commands. • Prevent committing bad code into codebase • How? • pre-commit runs these commands before we do git operations (e.g., git push, git commit)
  95. @clleew Config (customized hooks) .pre-commit-config.yaml repos: - repo: local hooks:

    - id: style-reformat name: style-reformat stages: [commit] language: system pass_filenames: false entry: inv style.reformat types: [python] - id: style-check name: style-check stages: [push] language: system pass_filenames: false entry: inv style types: [python] ......
  96. @clleew Config (customized hooks) .pre-commit-config.yaml repos: - repo: local hooks:

    - id: style-reformat name: style-reformat stages: [commit] language: system pass_filenames: false entry: inv style.reformat types: [python] - id: style-check name: style-check stages: [push] language: system pass_filenames: false entry: inv style types: [python] ...... entry: inv style.reformat - id: style-reformat stages: [commit]
  97. @clleew Config (customized hooks) .pre-commit-config.yaml repos: - repo: local hooks:

    - id: style-reformat name: style-reformat stages: [commit] language: system pass_filenames: false entry: inv style.reformat types: [python] - id: style-check name: style-check stages: [push] language: system pass_filenames: false entry: inv style types: [python] ...... stages: [push] - id: style-check
  98. @clleew Config (existing hooks) .pre-commit-config.yaml ...... - repo: https://github.com/pre-commit/pre-commit-hooks rev:

    v3.1.0 hooks: - id: end-of-file-fixer - id: trailing-whitespace args: [--markdown-linebreak-ext=md]
  99. @clleew Setup pre-commit

  100. @clleew Run pre-commit

  101. @clleew Run pre-commit

  102. @clleew Cultivate a git commit convention Speak formally

  103. None
  104. Hard to find to the right version

  105. commitizen-tools

  106. Commit - cz commit

  107. Commit - cz commit

  108. Commit - cz commit

  109. Commit - cz commit

  110. Commit - cz commit

  111. Commit - cz commit

  112. Commit - cz commit

  113. How does the commit look like? feat(Kaohsiung.py): This meetup is

    great Hope you enjoy these manners https://kaohsiungpy.kktix.cc/events/20200831
  114. Standardized git commits

  115. Other Commitizen features • pre-commit hook prevents you from not

    using commitizen • customizable commit rules • auto bump project version (SemVar) • auto generate changelog (Keep a Changelog)
  116. @clleew Security Issues Safety matters

  117. None
  118. None
  119. Safety Dependency Checking

  120. Check vulnerability in current environment

  121. Check vulnerability in current environment

  122. But if you use pipenv …

  123. But if you use pipenv …

  124. How does Safety work? • Search the vulnerability in CVS

    (Common Vulnerabilities and Exposures) • Free DB: update monthly • Paid DB: update realtime
  125. Bandit Static Analysis

  126. Check Common Security Issue in Python Code

  127. Check Common Security Issue in Python Code

  128. Check Common Security Issue in Python Code

  129. Check Common Security Issue in Python Code

  130. Check Common Security Issue in Python Code

  131. Not all the warnings should be fixed • Add exclude

    into your bandit configuration • Add # nosec after the end of the code to skip the warning
  132. @clleew

  133. @clleew Project template Where's the Cookie?

  134. @clleew We want these manners in all our Python projects

  135. @clleew We want these manners in all our Python projects

    ❗ But... we don't want to configure it everytime ❗
  136. @clleew Create a project template once and initialize projects through

    it
  137. @clleew Lee-W / cookiecutter-python-template

  138. @clleew

  139. @clleew

  140. @clleew

  141. @clleew

  142. @clleew

  143. @clleew How to make a template? cookiecutter.json

  144. @clleew How to make a template? cookiecutter.json

  145. @clleew Template structure Cookiecutter configuration Template (Use Jinja)

  146. @clleew An example in template {{cookiecutter.project_slug}}/tasks/env.py from invoke import task

    from tasks.common import VENV_PREFIX @task def init(ctx): """Install production dependencies""" {% if cookiecutter.dependency_management_tool == 'pipenv' -%} ctx.run("pipenv install --deploy") {%- elif cookiecutter.dependency_management_tool == 'poetry' -%} ctx.run("poetry install --no-dev") {%- endif %} {% if cookiecutter.dependency_management_tool == 'pipenv' -%} ctx.run("pipenv install --deploy")
  147. @clleew An example in template {{cookiecutter.project_slug}}/tasks/env.py from invoke import task

    from tasks.common import VENV_PREFIX @task def init(ctx): """Install production dependencies""" {% if cookiecutter.dependency_management_tool == 'pipenv' -%} ctx.run("pipenv install --deploy") {%- elif cookiecutter.dependency_management_tool == 'poetry' -%} ctx.run("poetry install --no-dev") {%- endif %} {% if cookiecutter.dependency_management_tool == 'pipenv' -%} ctx.run("pipenv install --deploy")
  148. @clleew An example in template {{cookiecutter.project_slug}}/tasks/env.py from invoke import task

    from tasks.common import VENV_PREFIX @task def init(ctx): """Install production dependencies""" {% if cookiecutter.dependency_management_tool == 'pipenv' -%} ctx.run("pipenv install --deploy") {%- elif cookiecutter.dependency_management_tool == 'poetry' -%} ctx.run("poetry install --no-dev") {%- endif %} {%- elif cookiecutter.dependency_management_tool == 'poetry' -%} ctx.run("poetry install --no-dev") {%- endif %}
  149. @clleew import os def remove_pipfile(): os.remove("Pipfile") def main(): if "{{

    cookiecutter.dependency_management_tool }}" != "pipenv": remove_pipfile() if __name__ == "__main__": main() Run before/after project is generated hooks/post_gen_project.py
  150. @clleew Lee-W / cookiecutter-python-template

  151. @clleew

  152. Other Tools • Testing • Hypothesis • nox • Documentation

    • Mkdocs • Sphinx
  153. @clleew Related Talks • Dependency Management • Tzu-ping Chung -

    這樣的開發環境沒問題嗎? (PyCon TW 2018) • Kenneth Reitz - Pipenv: The Future of Python Dependency Management (PyCon US 2018) • Patrick Muehlbauer - Python Dependency Management (PyCon DE 2018) • Test • Chun-Yu Tseng - 快快樂樂成為 Coding Ninja (by pytest) (PyCon APAC 2015) • Florian Bruhin – Pytest: Rapid Simple Testing (Swiss Python Summit 16)
  154. @clleew Related Talks • Style Check • Kyle Knapp -

    Automating Code Quality (PyCon US 2018) • Łukasz Langa - Life Is Better Painted Black, or: How to Stop Worrying and Embrace Auto-Formatting (PyCon US 2019) • Raymond Hettinger - Beyond PEP 8 -- Best practices for beautiful intelligible code (PyCon 2015) • Static Typing • Dustin Ingram - Static Typing in Python (PyCon US 2020) • Task Managements • Thea Flowers - Break the Cycle: Three excellent Python tools to automate repetitive tasks (PyCon US 2019) • Security • Terri Oda - Python Security Tools (PyCon US 2019) • Tennessee Leeuwenburg - Watch out for Safety Bandits! (PyCon AU 2018)
  155. @clleew References • pipenv • poetry • flake8 • pylint

    • mypy • black • isort • invoke • pre-commit • commitizen-tools • safety • bandit • cookiecutter
  156. @clleew