Python入门：如何通过docopt将initdb设置为True？

Hey there! Let's break this down step by step since you're new to docopt—it's totally normal to feel confused when first working with command-line argument parsers like this.

1. Understand docopt's core rule (the key fix!) #

Docopt relies entirely on the docstring at the top of your script (the __doc__ variable) to define valid command-line arguments. If your docstring doesn't explicitly list initdb as a valid command/option, docopt will default it to False no matter what you do.

For example, your script needs a docstring that looks something like this to recognize initdb:

"""Your Database App

Usage:
  your_script.py initdb
  your_script.py run

Options:
  -h --help  Show this help message.
"""

This tells docopt your script accepts two distinct commands: initdb (for database setup) and run (to start the app).

2. Run your script with the right terminal command #

Once your docstring is set up correctly, you need to pass the initdb argument when launching your script from the terminal:

• If you just run python your_script.py without any arguments, docopt can't match a valid command, so both initdb and run stay False (which is what you're seeing now).
• To flip initdb to True, run your script like this:

  python your_script.py initdb
  

3. Full working example to test #

Here's a complete script you can copy-paste and experiment with:

"""Sample Database App

Usage:
  app.py initdb
  app.py run

Options:
  -h --help  Show help information.
"""
from docopt import docopt

if __name__ == '__main__':
    args = docopt(__doc__)
    print(args)  # Will output {'initdb': True, 'run': False, '--help': False} when run with initdb
    
    if args['initdb']:
        print("Initializing database... Done!")
    elif args['run']:
        print("Starting application...")
    else:
        print("Please use either 'initdb' or 'run' as a command.")

When you run python app.py initdb, you'll see initdb set to True in the printed args, and the database initialization logic will execute.

内容的提问来源于stack exchange，提问作者Ahmed Ali