Agentic tools: greenfield vs legacy code

• Has the cost of building software just dropped 90%?
• More on Deprecation Warnings
• How FOSS Won and Why It Matters
• Should I be looking for a GitHub alternative?
• Extras
• Joke

About the show

Sponsored by us! Support our work through:

• Our courses at Talk Python Training
• The Complete pytest Course
• Patreon Supporters

Connect with the hosts

• Michael: @mkennedy@fosstodon.org / @mkennedy.codes (bsky)
• Brian: @brianokken@fosstodon.org / @brianokken.bsky.social
• Show: @pythonbytes@fosstodon.org / @pythonbytes.fm (bsky)

Join us on YouTube at pythonbytes.fm/live to be part of the audience. Usually Monday at 10am PT. Older video versions available there too.

Finally, if you want an artisanal, hand-crafted digest of every week of the show notes in email form? Add your name and email to our friends of the show list, we'll never share it.

HEADS UP: We are taking next week off, happy holiday everyone.

Michael #1: Has the cost of building software just dropped 90%?

• by Martin Alderson
• Agentic coding tools are collapsing “implementation time,” so the cost curve of shipping software may be shifting sharply
• Recent programming advancements haven’t been that great of a true benefit: Cloud, TDD, microservices, complex frontends, Kubernetes, etc.
• Agentic AI’s big savings are not just code generation, but coordination overhead reduction (fewer handoffs, fewer meetings, fewer blocks).
• Thinking, product clarity, and domain decisions stay hard, while typing and scaffolding get cheap.
• Is it the end of software dev? Not really, see Jevons paradox: when production gets cheaper, total demand can rise rather than spending simply falling. (Historically: the efficiency of coal use led to the increased consumption of coal)
• Pushes back on “only good for greenfield” by arguing agents also help with legacy code comprehension and bug-fixing. I 100% agree. #Legacy code for the win.

Brian #2: More on Deprecation Warnings

• How are people ignoring them?
  • yep, it’s right in the Python docs: -W ignore::DeprecationWarning
  • Don’t do that!
  • Perhaps the docs should give the example of emitting them only once
    • -W once::::DeprecationWarning
• See also <code>-X dev</code> mode , which sets -W default and some other runtime checks
• Don’t use warn, use the <code>@warnings.deprecated</code> decorator instead
  • Thanks John Hagen for pointing this out
  • Emits a warning
  • It’s understood by type checkers, so editors visually warn you
  • You can pass in your own custom UserWarning with category
• mypy also has a command line option and setting for this
  • --enable-error-code deprecated
  • or in [tool.mypy] enable_error_code = ["deprecated"]
• My recommendation
  • Use @deprecated
  • with your own custom warning
  • and test with pytest -W error

Michael #3: How FOSS Won and Why It Matters

• by Thomas Depierre
• Companies are not cheap, companies optimize cost control. They do this by making purchasing slow and painful.
• FOSS is/was a major unlock hack to skip procurement, legal, etc.
• Example is months to start using a paid “Add to calendar” widget!
• It “works both ways”: the same bypass lowers the barrier for maintainers too, no need for a legal entity, lawyers, liability insurance, or sales motion.
• Proposals that “fix FOSS” by reintroducing supply-chain style controls (he name-checks SBOMs and mandated processes) risk being rejected or gamed, because they restore the very friction FOSS sidesteps.

Brian #4: Should I be looking for a GitHub alternative?

• Pricing changes for GitHub Actions
  • The self-hosted runner pricing change caused a kerfuffle.
  • It’s has been postponed
• But… if you were to look around, maybe pay attention to
  • These 4 GitHub alternatives are just as good—or better
    • Codeburg, BitBucket, GitLab, Gitea
  • And a new-ish entry, Tangled

Extras

Brian:

• End of year sale for The Complete pytest Course
  • Use code XMAS2025 for 50% off before Dec 31
• Writing work on Lean TDD book on hold for holidays
  • Will pick up again in January

Michael:

• PyCharm has better Ruff support now out of the box, via Daniel Molnar
  • This is from the release notes of 2025.3: "PyCharm 2025.3 expands its LSP integration with support for Ruff, ty, Pyright, and Pyrefly.”
  • If you check out the LSP section it will land you on this page and you can go to Ruff.
  • The Ruff doc site was also updated. Previously it was only available external tools and a third party plugin, this feels like a big step.
• Fun quote I saw on ExTwitter: May your bug tracker be forever empty.

Joke:

• Try/Catch/Stack Overflow
• Create a super annoying linkedin profile - From Tim Kellogg, submitted by archtoad