I can't think of a case where the check for "\n" would result in a false negative. It likely makes sense to do that to keep python startup as lightweight as possible.
I've made a PR that implements a proof-of-concept: https://github.com/python/cpython/pull/103998 It's currently done via the Python C-API, but in terms of keeping things lightweight, I might need some help on how to effectively use the wide c-string API to implement this. On Mon, Apr 10, 2023 at 4:46 AM Barry <ba...@barrys-emacs.org> wrote: > > > On 10 Apr 2023, at 02:18, Jonathan Crall <erote...@gmail.com> wrote: > > > There's no question that there are lots of ways you can work around the > issue (I think the `if 1:` method is the easiest and most portable, but it > still is boilerplate which can be confusing if you don't know why it's > there). The question is: would enough people benefit from this to add the > feature to CPython? > > > A PR that has an implementation might push this forward. > I wonder if in the C code of -c treating a string that starts with \n > could trigger the dedent? > > Barry > > > > > On Sun, Apr 9, 2023 at 4:09 PM Barry Scott <ba...@barrys-emacs.org> wrote: > >> >> On 04/04/2023 15:18, Jonathan Crall wrote: >> >> I have what I think is a fairly low impact quality of life improvement to >> suggest for the python CLI. >> >> When I'm not working in Python I tend to be working in bash. But often I >> want to break out and do something quick in Python. I find the `python -c ` >> CLI very useful for this. For one liners it's perfect. E.g. >> >> NEW_VAR=$(python -c "import pathlib; >> print(pathlib.Path('$MYVAR').parent.parent)") >> >> And even if I want to do something multi-line it's pretty easy >> >> NEW_VAR=$(python -c " >> import pathlib >> for _ in range(10): >> print('this is a demo, bear with me') >> ") >> >> But the problem is when I'm writing bash inside a function or some other >> nested code, I would like to have nice indentation in my bash file, but if >> I write something like this: >> >> mybashfunc(){ >> python -c " >> import pathlib >> for _ in range(10): >> print('this is a demo, bear with me') >> " >> } >> >> I get `IndentationError: unexpected indent`. >> >> This means I have to write the function ugly like this: >> >> mybashfunc(){ >> python -c " >> import pathlib >> for _ in range(10): >> print('this is a demo, bear with me') >> " >> } >> >> Or use a helper function like this: >> >> codeblock() >> { >> __doc__=' >> copy-pastable implementation >> Prevents indentation errors in bash >> ' >> echo "$1" | python -c "import sys; from textwrap import dedent; >> print(dedent(sys.stdin.read()).strip('\n'))" >> } >> >> mybashfunc(){ >> python -c $(codeblock " >> import pathlib >> for _ in range(10): >> print('this is a demo, bear with me') >> ") >> } >> >> Or more recently I found that this is a low-impact workaround: >> >> mybashfunc(){ >> python -c "if 1: >> import pathlib >> for _ in range(10): >> print('this is a demo, bear with me') >> " >> } >> >> But as a certain Python dev may say: "There must be a better way." >> >> Would there be any downside to the Python CLI automatically dedenting the >> input string given to -c? I can't think of any case off the top of my head >> where it would make a previously valid program invalid. Unless I'm missing >> something this would strictly make previously invalid strings valid. >> >> Thoughts? >> >> You can solve this with a small module. I named mine run_dedent >> >> mkdir -p run_dedent >> echo pass >run_dedent/__init__.py >> cat <<EOF >run_dedent/__main__.py >> import sys >> import textwrap >> cmd = textwrap.dedent(sys.argv[1]) >> exec(cmd) >> EOF >> >> python3 -m run_dedent " >> import sys >> print(sys.version_info) >> " >> >> Barry >> >> >> >> -- >> -Dr. Jon Crall (him) >> >> _______________________________________________ >> Python-ideas mailing list -- python-ideas@python.org >> To unsubscribe send an email to >> python-ideas-leave@python.orghttps://mail.python.org/mailman3/lists/python-ideas.python.org/ >> Message archived at >> https://mail.python.org/archives/list/python-ideas@python.org/message/6SYN2MQIP5DTF6INZ4SP2YKLF6P4VJOW/ >> Code of Conduct: http://python.org/psf/codeofconduct/ >> >> > > -- > -Dr. Jon Crall (him) > > -- -Dr. Jon Crall (him)
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