PEP 704: Require virtual environments by default for installers

[pradyunsg]

Enforce the use of virtual environments and establish a conventional name for the virtual environment directory.

[CAM-Gerlach]

Looks like PEP 704 is available, so it's all yours.

[CAM-Gerlach]

Basic requirements (all PEP Types)

• File created from the latest PEP template
• PEP has next available number, with filename (pep-NNNN.rst) and PEP header set accordingly
• Title clearly, accurately and concisely describes the content in 79 characters or less
• PEP, Title, Author, Status (Draft), Type and Created headers filled out correctly
• Sponsor, PEP-Delegate, Topic, Requires and Replaces headers completed if appropriate
• Required sections included
  • Abstract (first section)
  • Copyright (last section; exact wording from template required)
• Code is well-formatted (PEP 7/PEP 8) and is in code blocks, with the right lexer names if non-Python
• PEP builds with no warnings, pre-commit checks pass and content displays as intended in the rendered HTML
• Authors/sponsor added to .github/CODEOWNERS for the PEP

Standards Track requirements

• PEP topic discussed in a suitable venue with general agreement that a PEP is appropriate
• Suggested sections included (unless not applicable)
  • Motivation
  • Rationale
  • Specification
  • Backwards Compatibility
  • Security Implications
  • How to Teach This
  • Reference Implementation
  • Rejected Ideas
  • Open Issues
• Python-Version set to valid (pre-beta) future Python version Not needed for Packaging PEP that doesn't touch core Python
• Any project stated in the PEP as supporting/endorsing/benefiting from it confirms such
• Right before or after initial merging, PEP discussion thread created and linked to in Discussions-To and Post-History

General comments

• When you're just referring to pip, the name of the package installer (as opposed to running the pipcommand on a CLI), I would suggest omitting the literal formatting, to be semantically correct, consistent with other names and pip's own docs, and avoid visual noise in the source and rendered output.
• Just FYI, we've enabled Intersphinx against both the Python.org docs and packaging.python.org, so you can use all the normal directives you'd expect (:ref:, :term:, :module:, etc) to link against things like the PyPA glossary (which is rather outdated though I have some proposed updates in the works; for my working draft of PEP 639 I basically had to redefine most of the relevant terms myself with updated definitions).
• I've included a handful of non-suggestion comments regarding the PEP clearly and precisely expressing what it intends to in terms of terminology and rationale, that may stray a bit into the gray area of content/subject matter expertise. If you feel any of them stray too far, I can defer them here and bring them up on the thread instead.

[pradyunsg]

Are there any blocking concerns here, or can this be merged?

[JelleZijlstra]

Did Brett (as the sponsor) approve the text of the PEP?

Also, you should add the PEP to CODEOWNERS (it's in CAM's checklist above; there's also an entry unchecked about headers but I am not sure what the issue is).

[pradyunsg]

Yes: #2964 (comment)

CODEOWNERS added.

[JelleZijlstra]

OK, then I think we can merge but I'll wait for a bit for @CAM-Gerlach to confirm.

[CAM-Gerlach]

there's also an entry unchecked about headers but I am not sure what the issue is).

That was for confirming that the sponsor approved*; I saw Brett's comment and marked it as resolved, but forgot to update the checklist accordingly, sorry. Everything's checked now ✔️ ; there's just a handful of remaining small typos, textual fixes and syntax tweaks that either got missed from suggestions that were outdated/resolved for other reasons, on newly added material, or that I missed the first time around.

* In earlier versions of the checklist, I had a separate item for that, but Petr suggested merging it with the others which I went along with, which I'm now having second thoughts about...but I don't want to drag #2956 out even more since I already revised it several times.

[CAM-Gerlach]

A handful of remaining small typos, textual fixes and syntax tweaks that either got missed from suggestions that were outdated/resolved for other reasons, on newly added material, or that I missed the first time around. Besides that, and in terms of the checklist, LGTM, thanks.

[pradyunsg]

Any blockers to landing this?

[potiuk]

Just a comment about that one. I really like that we have an opt-out now rather than opt-in (but it's good we have an explicit opt-out as well that is useful in many cases - for example in most container use-cases. Those are specific use-cases and having and opt-out possible is more than enough for those cases - especially for legacy use cases.

Also having a default convention for the venv usage is great as part of this PEP. This will make a number of use-cases simpler and less decisions to make and having implicit steps for activation of ~/.venv environment is a good one too.

[pradyunsg]

Please don't comment on the PR, there's a discuss.python.org thread for this PEP which is where discussions should happen.

[potiuk]

Please don't comment on the PR, there's a discuss.python.org thread for this PEP which is where discussions should happen.

sure. I was not sure what the etiquette is but if you say so, I am happy to add this comment to the discourse.