[Python-ideas] Auto dedent -c arguments.

4 Apr 2023

      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?

-- 
-Dr. Jon Crall (him)

[Python-ideas] Auto dedent -c arguments.

Jonathan Crall