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GeezerVison is showing github.com — PEP 750: collect spec fixes discovered during final implementation work by davepeck · Pull Request #4364 · python/peps

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@davepeck

@davepeck davepeck commented Apr 11, 2025 •
edited by AA-Turner
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  • Change is either:
    • To a Draft PEP
    • To an Accepted or Final PEP,
      • with Steering Council approval
    • To fix an editorial issue (markup, typo, link, header, etc)
  • PR title prefixed with PEP number (e.g. PEP 123: Summary of changes)

Hate to do this < 24 hours after acceptance, but as we've been going through the spec with a fine-tooth comb, @lysnikolaou and I discovered a minor spec issue in PEP 750.

The intent of the debug specifier behavior is to precisely match the behavior of current day f-strings. The PEP as accepted got one detail wrong, fixed here.

(The wrong detail: if a debug specifier is used with a format spec but no conversion — t"{value=:foo}" — the Interpolation.conversion should default to None, not s as in the accepted PEP. Having s as the default would be a departure from what f-strings do: they provide no default when there's a format_spec so that __format__() is called.)

📚 Documentation preview 📚: https://pep-previews--4364.org.readthedocs.build/

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@davepeck
Spec fix: make the debug spec section fully match f-string behavior
0e29282
@davepeck
davepeck requested review from gvanrossum and lysnikolaou as code owners April 11, 2025 14:57
@davepeck
Fix lint issue
954899c
@davepeck davepeck changed the title Spec fix: make the debug spec section fully match f-string behavior PEP 750: spec fix: make the debug spec section fully match f-string behavior Apr 11, 2025
davepeck added 2 commits April 11, 2025 08:08
@davepeck
!s, not :s
3ee5299
@davepeck
conversion
51ca27e
@AA-Turner

AA-Turner commented Apr 11, 2025

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It might make sense to bundle all PEP changes discovered during implementation into one PR before marking the PEP as Final?

If changes based on implementation experience and user feedback are made to Standards track PEPs while in the Provisional or (with SC approval) Accepted state, they should be noted in the PEP, such that the PEP accurately describes the implementation at the point where it is marked Final.

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@davepeck

davepeck commented Apr 11, 2025 •
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It might make sense to bundle all PEP changes discovered during implementation into one PR before marking the PEP as Final?

That makes sense. I believe that this is the only spec issue that will crop up; the implementation is largely complete and spec-matching. But to be safe, collecting/waiting until we merge into cpython beta makes sense.
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@lysnikolaou

lysnikolaou commented Apr 11, 2025

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Yes, agreed. Let's keep this PR open (possibly also change the title) while we're finilizing the implementation and at least until some more people have reviewed it.
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@davepeck davepeck changed the title PEP 750: spec fix: make the debug spec section fully match f-string behavior PEP 750: collect spec issues fixes discovered during final implementation work Apr 11, 2025
@davepeck davepeck changed the title PEP 750: collect spec issues fixes discovered during final implementation work PEP 750: collect spec fixes discovered during final implementation work Apr 11, 2025
@davepeck davepeck mentioned this pull request Apr 11, 2025
When debug specifier _and_ format_spec are present, use !s as the conversion default lysnikolaou/cpython#63
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@davepeck
Merge branch 'main' into pep750-debug-specifier-fix
d172707
@davepeck

davepeck commented Jun 26, 2025

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We should consider how to sequence this PR (collecting miscellaneous updates) and #4395 (the template concatenation PR)
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davepeck added 2 commits June 26, 2025 10:03
@davepeck
Merge branch 'main' into pep750-debug-specifier-fix
270ac1d
@davepeck
Clarify behavior of Interpolation.expression and add a default value.
77fe765
@davepeck

davepeck commented Jun 26, 2025

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Hi @lysnikolaou !

As we discussed during PyCon, I've updated the PEP to:

  1. Clarify the behavior of Interpolation.expression
  2. Make Interpolation.expression default to "" (currently a value must be provided when explicitly constructing an Interpolation)

The second change is a small but meaningful spec/implementation change — should we also open a steering council issue, or is it okay as is?

/cc @AA-Turner
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@davepeck davepeck mentioned this pull request Jun 27, 2025
gh-135676: Lexical analysis: Reword String literals and related sections python/cpython#135942
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lysnikolaou
lysnikolaou approved these changes Jun 30, 2025
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LGTM!

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Merge branch 'main' into pep750-debug-specifier-fix
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@davepeck

davepeck commented Jul 8, 2025

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This one is ready to merge, I think @AA-Turner !
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This was referenced Jul 8, 2025
Mark 3.14 PEPs as Final #4437
Open
gh-132661: Add default value (of "") for Interpolation.expression python/cpython#136441
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AA-Turner
AA-Turner approved these changes Aug 5, 2025
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@AA-Turner

AA-Turner commented Aug 5, 2025

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Shall we capture the changes to t-string concatenation here @davepeck?

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@davepeck

davepeck commented Aug 5, 2025 •
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Shall we capture the changes to t-string concatenation here @davepeck?

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@AA-Turner Think we captured those in #4395, already merged.
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@davepeck
Merge branch 'main' into pep750-debug-specifier-fix
038c02c
@AA-Turner

AA-Turner commented Aug 5, 2025

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Oops! My mistake, sorry!

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@AA-Turner
AA-Turner enabled auto-merge (squash) August 5, 2025 21:38
@davepeck

davepeck commented Aug 5, 2025 •
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Oops! My mistake, sorry!

Hah! There are so many PEP 750 related PRs at this point that I've personally entirely lost the plot. 😅
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@AA-Turner
AA-Turner merged commit c77e600 into python:main Aug 5, 2025
ethanfurman pushed a commit to ethanfurman/peps that referenced this pull request Oct 8, 2026
@davepeck @ethanfurman
PEP 750: Collect spec fixes discovered during final implementation wo…
eb8bdc9 
…rk (python#4364)
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@AA-Turner AA-Turner AA-Turner approved these changes
@lysnikolaou lysnikolaou lysnikolaou approved these changes
@gvanrossum gvanrossum Awaiting requested review from gvanrossum gvanrossum is a code owner

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3 participants

@davepeck @AA-Turner @lysnikolaou
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