How to indent correctly multi-line list of arguments inside function call in Python [closed]-CodePudding

I want to create this multi-line function call. The examples that I find for nested constructs they assume that there is a character starting each line i Cannot find an example where a bracket [ is followed by a parenthesis ( without anything in between.

So how would I format this:

  subprocess.run(['docker-compose', '-f', 'docker-compose.test.yml', '-f',
                   'docker-compose.services.yml', '-f', 'docker-compose.dev.yml', 'down'],
                 stdout=subprocess.DEVNULL
  )

where should the bracket go? How should i format the list of arguments? Is it ok if I have multiple on the same line? Or should each argument has its own line

CodePudding user response：

You can do something like this

import subprocess

subprocess.run(
    [
        'docker-compose', '-f', 'docker-compose.test.yml', '-f',
        'docker-compose.services.yml', '-f', 'docker-compose.dev.yml', 'down'
    ],
    stdout=subprocess.DEVNULL
)

CodePudding user response：

I personally like to use black to answer questions of formatting. It's more strict that PEP8 and makes some hard decisions I don't always agree with, but I've actually started using it systematically, it really saves a lot of wasted time worrying about formatting.

Here's what black did with this code:

subprocess.run(
    [
        "docker-compose",
        "-f",
        "docker-compose.test.yml",
        "-f",
        "docker-compose.services.yml",
        "-f",
        "docker-compose.dev.yml",
        "down",
    ],
    stdout=subprocess.DEVNULL,
)

I have to say if I was formatting this by hand, I would prefer keeping switches and their values on the same line, so I would probably do this:

subprocess.run(
    [
        "docker-compose",
        "-f", "docker-compose.test.yml",
        "-f", "docker-compose.services.yml",
        "-f", "docker-compose.dev.yml",
        "down",
    ],
    stdout=subprocess.DEVNULL,
)

And I also think prnvbn's answer is just as good.

Now, PEP8 is not actually strict about all this, I think it accepts several options on placing the closing ] and ), and it also seems to be flexible on whether the first element appears on the same line as what contains it or not. While I don't like your formatting much, it might actually still be PEP8 compliant, except for the fact that your second line is longer than 79 characters.

CodePudding user response：

As other have said, PEP8 gives several options with respect to this and, between those, whichever you choose is matter of personal preference. Personally, I like my code lines to be compact with a number of white lines in between to demark whenever I'm doing something different (e.g., initializing variables vs. computing something). In this case, I would go with (i.e., my personal preference):

  subprocess.run(['docker-compose', '-f',
                  'docker-compose.test.yml', '-f',
                  'docker-compose.services.yml', '-f',
                  'docker-compose.dev.yml', 'down'],
                 stdout=subprocess.DEVNULL)

Note however that if you are coding this in the context of a project or while working on code started by others, you generally want to follow the preferences and style that the code exhibits already.