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How do I, with one regex, transform:

logger.info(f"Foo {alpha}")
logger.info(f"Foo {alpha} bar {beta}")
logger.info(f"Foo {alpha} bar {beta} baz {gamma}")

Into:

logger.info("Foo %s", alpha)
logger.info(f"Foo %s bar %s", alpha, beta)
logger.info(f"Foo %s bar %s baz %s", alpha, beta, gamma)

Background:

Idiomatically, log strings in Python should be written using "percent formatting", similar to formatting strings in c using printf, e.g.

o = { "lemurian": "lemurs" }
p = "are leaping"
logger.info("Something something %s %s", o, p)

Which outputs "Something something { "lemurian": "lemurs" } are leaping".

However, I have written lots of log messages with directly interpolated values, e.g.

o = { "lemurian": "lemurs" }
p = "are leaping"
logger.info("Something something {o} {p}")

Which outputs the same as above. I can change things by hand, but it's a pain. :D

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  • 1
    If your python supports f-strings, it's a vastly easier problem to simply add f to the beginning of strings (though still not error-free)
    – D. Ben Knoble
    Nov 10 '21 at 18:25
  • 1
    I suspect this is related and may help: vi.stackexchange.com/questions/30981/…
    – D. Ben Knoble
    Nov 10 '21 at 18:26
  • 1
    @D.BenKnoble I'm trying to get rid of the f-strings. :)
    – Kit Peters
    Nov 10 '21 at 18:28
  • 1
    Yeah, on second thought, that post may not be too helpful.
    – D. Ben Knoble
    Nov 10 '21 at 18:33
  • 1
    Why "one regex" (which I assume means "one substitution")? If this is just about getting the job done, I should think that one macro, one command (or series of commands) or even one function would be acceptable, no? Basically, "one operation"...
    – B Layer
    Nov 10 '21 at 18:43
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Here's a macro that does the transformation for a single {} that uses surround.vim:

let @q = "0f{ca}%s\<esc>f)i, \<esc>pds{"

(You can also record this by hand.)

Now, unfortunately, running this once for each {} group is harder. You could do it manually, of course, with /{Entern@qn@@n@@…. You can get part of the way to automation with

:global/logger.info(f/normal! @q

which does a single step, and then you can iterate that with @: until there are no more brace-groups.

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