Simplify Command-Line Interfaces with docopt

Simplify Command-Line Interfaces with docopt

Are you tired of writing repetitive and error-prone code to generate help messages for your command-line interfaces? Look no further than docopt, a Python library that simplifies the creation of beautiful and intuitive command-line interfaces. With docopt, you can generate option parsers based on your own help messages, eliminating the need for manual parser code.

What is docopt?

docopt is a Python library that parses usage patterns and option descriptions to automatically generate option parsers for your command-line interfaces. It allows you to write a clear and concise help message, which serves as the basis for the option parser. docopt ensures that the program invocation matches the usage pattern and parses options, arguments, and commands accordingly.

Getting Started with docopt

To get started with docopt, you need to specify the usage pattern and option descriptions in your help message. The usage pattern defines the structure of the command-line interface, including the arguments, options, and commands. Option descriptions specify the synonymous short and long options, whether an option has an argument, and the default value for an option’s argument.

Here’s an example of a help message for a fictional command-line interface called “Naval Fate”:

"""Naval Fate.

Usage:
naval_fate.py ship new ...
naval_fate.py ship move [--speed=]
naval_fate.py ship shoot
naval_fate.py mine (set|remove) [--moored | --drifting]
naval_fate.py (-h | --help)
naval_fate.py --version

Options:
-h --help Show this screen.
--version Show version.
--speed= Speed in knots [default: 10].
--moored Moored (anchored) mine.
--drifting Drifting mine.

"""

In this example, the usage pattern defines several commands, including “ship”, “mine”, “-h”, and “–version”. The option descriptions specify the synonymous short and long options, whether an option has an argument, and the default value for an option’s argument.

Generating the Option Parser

Once you have defined your help message, you can generate the option parser using the docopt library. Simply pass your help message to the docopt function, along with any other necessary arguments, such as the version of your program. The return value is a dictionary that contains the options, arguments, and commands, spelled exactly as they are in your help message.

from docopt import docopt

if name == 'main':
arguments = docopt(doc, version='Naval Fate 2.0')
print(arguments)

In this example, the docopt function is called with the help message and the version argument. The returned dictionary, “arguments”, contains the parsed options, arguments, and commands.

Advanced Usage

docopt offers more advanced features for configuring your command-line interfaces. You can specify whether options and positional arguments can be repeated, enforce strict separation of options and positional arguments, and handle subcommands with separate help screens. docopt also supports data validation and integration with configuration files.

Conclusion

docopt is a powerful Python library that simplifies the creation of command-line interfaces. By generating option parsers based on your own help messages, docopt eliminates the need for manual parser code and allows you to create beautiful and intuitive command-line interfaces. Get started with docopt today and simplify your command-line interface development.

Source: GitHub – docopt/docopt