[Python-ideas] Re: Auto dedent -c arguments.

9 Apr 2023


      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 topython-ideas-leave@python.org
https://mail.python.org/mailman3/lists/python-ideas.python.org/
Message archived athttps://mail.python.org/archives/list/python-ideas@python.org/message/6SYN2M...
Code of Conduct:http://python.org/psf/codeofconduct/

[Python-ideas] Re: Auto dedent -c arguments.

Barry Scott