Python Ecosystem Advances: Language, Libraries, and Developer Tools - Episode Hero Image

Python Ecosystem Advances: Language, Libraries, and Developer Tools

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Original Title:

TL;DR

  • PEP 798 introduces unpacking in comprehensions, simplifying the creation of lists, sets, dictionaries, and generators from iterables, and resolving the complexity of nested comprehensions.
  • Pandas 3.0rc0 adopts a dedicated string dtype by default and implements Copy-on-Write, enhancing predictability and potentially reducing memory usage by managing data copies more efficiently.
  • The typos tool offers advanced misspelling detection within code, including camelCase and snake_case, with superior editor integration via LSP compared to codespell.
  • slowlify allows simulation of resource-constrained environments to reproduce CI failures locally, aiding in the debugging of flaky tests.
  • Ned Batchelder's article highlights the critical importance of mocking objects where they are used, not where they are defined, to prevent unexpected test failures and coverage issues.
  • The tabloid programming language offers a novel, humorous approach to coding, inspired by clickbait headlines and featuring an all-caps syntax.

Deep Dive

Python 3.15 is set to introduce "splatted comprehensions" via PEP 798, allowing for more intuitive unpacking of iterables within list, set, dictionary, and generator comprehensions. This change addresses the complexity of nested comprehensions and brings consistency to unpacking syntax across Python, a significant enhancement for expressing complex data transformations concisely. Concurrently, Pandas 3.0.0rc0 signals a major release with a dedicated string data type by default, enforcing string-only content and using NaN as the missing value sentinel, thereby improving data integrity and performance. This release also introduces Copy-on-Write, which aims to make indexing operations more predictable and memory-efficient by deferring copies until actual modifications occur.

The Python ecosystem is also seeing advancements in developer tooling. The typos project, a misspelling finder written primarily in Rust, offers superior detection of errors within snake_case and camelCase identifiers compared to traditional spell checkers. Its integration via a Language Server Protocol (LSP) enables real-time error highlighting and quick fixes within IDEs like VS Code, a significant improvement over tools lacking such editor integration and a direct benefit for maintaining code quality. For testing, slowlify provides a means to simulate resource-constrained environments on Linux, enabling developers to reproduce and debug CI-specific failures locally. Furthermore, Ned Batchelder's insights on mocking emphasize a crucial best practice: mock where an object is used, not where it is defined, to prevent subtle bugs and ensure test reliability, particularly in conjunction with tools like coverage.py.

These developments collectively point to a Python ecosystem that is maturing with improved language features for expressiveness, more robust data manipulation libraries, and enhanced developer tools for code quality and testing. The adoption of more explicit and predictable patterns in both language constructs and library APIs, as seen in PEP 798 and Pandas 3.0, suggests a continued focus on developer experience and maintainability. The emphasis on sophisticated tooling like typos and slowlify demonstrates a proactive approach to catching errors early and simulating real-world deployment conditions, ultimately contributing to more stable and efficient software development.

Action Items

  • Audit typos integration: Implement typos as a pre-commit hook across 3-5 core repositories to catch misspellings within code.
  • Implement slowlify for testing: Configure slowlify to simulate resource constraints for 2-3 critical CI jobs to reproduce and debug flaky tests.
  • Refactor mocking strategy: For 5-10 key modules, update mock implementations to patch at the point of use, not at the import level, to prevent future test brittleness.
  • Evaluate Pandas 3.0 features: Analyze the impact of dedicated string dtypes and copy-on-write on 2-3 high-volume data processing pipelines.

Related Episodes

Key Quotes

"After careful deliberation, the Python Steering Council is pleased to accept PEP 798 -- Unpacking in Comprehensions."

The Python Steering Council has accepted PEP 798, which introduces unpacking capabilities into comprehensions. Michael Kennedy explains that this PEP aims to bring consistency to Python's syntax, allowing for more intuitive ways to handle iterables within list, set, dictionary, and generator comprehensions.

"Pandas 3.0.0 will be released soon, and we’re on Release candidate 0. Here’s What’s new in Pands 3.0.0: Dedicated string data type by default. Inferred by default for string data (instead of object dtype). The str dtype can only hold strings (or missing values), in contrast to object dtype. (setitem with non string fails). The missing value sentinel is always NaN (np.nan) and follows the same missing value semantics as the other default dtypes."

Brian Okken highlights significant changes in the upcoming Pandas 3.0.0 release, including a dedicated string data type. This new str dtype will exclusively store strings or missing values, preventing the inclusion of unexpected data types and improving data integrity compared to the previous object dtype.

"Like codespell, typos checks for known misspellings instead of only allowing words from a dictionary. But typos has some extra features I really appreciate, like finding spelling mistakes inside snake_case or camelCase words. For example, if you have the line: *connecton_string = "sqlite:///my.db"* codespell won't find the misspelling, but typos will."

Michael Kennedy introduces "typos," a tool that goes beyond traditional spell checkers by identifying misspellings within programming identifiers like snake_case or camelCase. He contrasts this with codespell, noting that "typos" can detect errors such as "connecton" within "connecton_string," which other tools might miss.

"Simulate slow, overloaded, or resource-constrained machines to reproduce CI failures and hunt flaky tests. Requires Linux with cgroups v2"

Brian Okken discusses "slowlify," a tool designed to simulate machine constraints like low memory or CPU availability. The purpose of "slowlify" is to help developers reproduce and diagnose intermittent test failures that occur in continuous integration (CI) environments but not on local machines, requiring a Linux environment with cgroups v2.

"Ned’s taught us before to “Mock where the object is used, not where it’s defined.” To be more explicit, but probably more confusing to mock-newbies, “don’t mock things that get imported, mock the object in the file it got imported to.”"

Brian Okken references Ned Batchelder's advice on mocking in software testing. Batchelder's principle, "Mock where the object is used, not where it’s defined," emphasizes mocking the specific instance of an object within the file where it is imported and utilized, rather than attempting to mock it at its original definition point.

Resources

External Resources

Books

  • "The Complete pytest Course" - Mentioned as a course available through Talk Python Training.

Articles & Papers

  • "PEP 798: Unpacking in Comprehensions" (Python Discuss) - Mentioned as a proposal targeting Python 3.15 for unpacking in comprehensions.
  • "PEP 810, Explicit lazy imports" (Python Discuss) - Mentioned as unanimously accepted by the Steering Council.
  • "What’s new in Pands 3.0.0" (Pandas Documentation) - Discussed as detailing changes in the upcoming Pandas 3.0.0 release.
  • "Why your mock breaks later" (Ned Batchelder's Blog) - Referenced for best practices in mocking, specifically advising against patching imported objects.
  • "The Rise and Rise of FastAPI" (YouTube Mini Documentary) - Mentioned as a video featuring Sebastian Ramirez discussing FastAPI.
  • "Django 6 is out" (Django Weblog) - Mentioned as the official release of Django 6.

Tools & Software

  • Pandas 3.0.0rc0 (GitHub) - Mentioned as a release candidate for the Pandas library.
  • typos (GitHub) - Discussed as a misspelling finder tool with editor integration, an alternative to codespell.
  • slowlify (GitHub) - Mentioned as a tool to simulate slow or resource-constrained machines for testing.
  • tabloid - Mentioned as a minimal programming language inspired by clickbait headlines.

People

  • Adam Hartz - Mentioned as a proposer for PEP 798.
  • Eric Demaine - Mentioned as a proposer for PEP 798.
  • Yella Jastrzembska - Mentioned as the sponsor for PEP 798.
  • Sky Kasko - Mentioned as the individual who recommended the typos tool.
  • Brian Skinn - Mentioned as the sender of the slowlify tool suggestion.
  • Ned Batchelder - Mentioned as the author of the article "Why your mock breaks later."
  • Sebastian Ramirez - Mentioned in relation to a mini-documentary about FastAPI.
  • Hugo Bone - Mentioned as a co-host on the Vanishing Gradients podcast episode.
  • Anderson - Mentioned as a co-host on the Vanishing Gradients podcast episode.

Organizations & Institutions

  • Python Steering Council - Mentioned for accepting PEP 798 and PEP 810.
  • Talk Python Training - Mentioned as a provider of courses, including a pytest course.
  • Patreon Supporters - Mentioned as a way to support the show.
  • crate-ci - Mentioned as the organization behind the typos tool.
  • Pypy - Mentioned as a source for installing the typos tool.
  • VS Code - Mentioned as an editor with an extension for the typos tool.
  • OpenVSX Registry - Mentioned as a registry for editor extensions, including typos.
  • Neovim - Mentioned as an editor that can use the typos LSP.
  • Vim - Mentioned as an editor that can use the typos LSP.
  • Zed - Mentioned as an editor that can use the typos LSP.
  • GitHub - Mentioned in relation to typos and a common mocking issue.
  • Google - Mentioned in relation to the tabloid programming language.
  • Facebook - Mentioned in relation to the tabloid programming language.

Courses & Educational Resources

  • AI Agent Course - Mentioned as a recently completed course by Michael Kennedy.
  • "Building on Lean" chapter of LeanTDD - Mentioned as a released chapter of an ebook.
  • "Finding Waste in TDD" - Mentioned as the next chapter to be written for the LeanTDD ebook.

Websites & Online Resources

  • pythonbytes.fm/live - Mentioned as the URL for the show's YouTube stream.
  • pythonbytes.fm/friends-of-the-show - Mentioned as the link to subscribe to the show's newsletter.
  • discuss.python.org - Mentioned as the source for PEP discussions.
  • github.com/pandas-dev/pandas/releases - Mentioned for the Pandas release notes.
  • pandas.pydata.org/docs/dev/whatsnew/v3.0.0.html - Mentioned for detailed information on Pandas 3.0.0 changes.
  • github.com/crate-ci/typos - Mentioned as the repository for the typos tool.
  • marketplace.visualstudio.com/items?itemName=tekumara.typos-vscode - Mentioned as the VS Code extension for typos.
  • open-vsx.org/extension/tekumara/typos-vscode - Mentioned as the OpenVSX extension for typos.
  • github.com/crate-ci/typos/blob/master/docs/comparison.md - Mentioned as a comparison table between codespell and typos.
  • pypi.org/project/typos/ - Mentioned as the PyPI page for the typos tool.
  • github.com/crate-ci/typos/blob/master/docs/pre-commit.md - Mentioned for using typos as a pre-commit hook.
  • prek.j178.dev/ - Mentioned as an alternative to pre-commit.
  • github.com/crate-ci/typos/blob/master/docs/github-action.md - Mentioned for the typos GitHub action.
  • github.com/pablogsal/slowlify - Mentioned as the repository for the slowlify tool.
  • nedbatchelder.com/blog/202511/why_your_mock_breaks_later.html - Mentioned as the URL for Ned Batchelder's article on mocking.
  • vanishinggradients.fireside.fm/64 - Mentioned as the URL for Michael Kennedy's appearance on the Vanishing Gradients podcast.
  • djangoproject.com/weblog/2025/dec/03/django-60-released/ - Mentioned as the official announcement for Django 6.0.
  • github.com/thesephist/tabloid - Mentioned as the repository for the tabloid programming language.
  • youtube.com/watch?v=mpR8ngthqiE - Mentioned as the link to a mini-documentary about FastAPI.

Podcasts & Audio

  • Python Bytes - Mentioned as the podcast where this episode was recorded.
  • Vanishing Gradients - Mentioned as a podcast Michael Kennedy appeared on.

Other Resources

  • PEP 798 - Mentioned as a proposal for unpacking in comprehensions.
  • PEP 810 - Mentioned as a proposal for explicit lazy imports.
  • Object dtype - Mentioned in contrast to the new dedicated string data type in Pandas.
  • Copy-on-Write - Mentioned as a feature in Pandas 3.0.0.
  • codespell - Mentioned as a misspelling finder tool, contrasted with typos.
  • LSP (Language Server Protocol) - Mentioned in relation to the typos tool's editor integration.
  • Cgroups v2 - Mentioned as a requirement for running the slowlify tool.
  • Mocking - Discussed as a testing technique with best practices and pitfalls.
  • Auto spec=True - Mentioned as a parameter for mocks to ensure strict behavior.
  • Functional Core, Imperative Shell - Mentioned as a mocking practice discussed by Ned Batchelder.
  • Dependency Injection - Mentioned as a mocking practice discussed by Ned Batchelder.
  • FastAPI - Mentioned in the context of a mini-documentary.
  • Lean TDD - Mentioned as an ebook in progress.
  • Django 6 - Mentioned as a recently released version.
  • Lolcats - Mentioned as a previous example of a joke programming language.

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