7+ Argparse Python 使い方 Ideas

Изучаем Python модуль argparse from www.pvsm.ru

Introduction

Argparse is a Python library used for parsing command-line arguments. It is a standard module in Python, which means it comes pre-installed with the language. Argparse makes it easy to write user-friendly command-line interfaces by providing a simple way to define the arguments a program accepts.

What is Command-line Interface?

Command-line interface (CLI) is a way of interacting with a computer program where the user enters commands into a terminal or console. CLI is often used by developers, system administrators, and power users to perform complex tasks quickly and efficiently.

Why Use Argparse?

While writing a command-line interface, you need to handle various arguments to provide a smooth experience to the users. Argparse makes it easy to define and handle these arguments. It provides features like type checking, default values, help messages, and more.

Installation

Argparse is a standard module in Python, so you don't need to install anything. You can import it like any other module:

import argparse

Basic Usage

The first step is to create an instance of the ArgumentParser class:

parser = argparse.ArgumentParser()

You can add arguments to the parser using the add_argument() method. The method takes several arguments like name, type, default value, help message, and more. Here's an example:

parser.add_argument('--name', type=str, default='World', help='Name to greet')

This command adds an argument called --name to the parser. The argument expects a string value and has a default value of 'World'. The help message explains what the argument does. After adding all the arguments, you can parse the command-line arguments using the parse_args() method:

args = parser.parse_args()

This method returns an object that contains the parsed values of the arguments.

Advanced Usage

Argparse provides many advanced features like sub-commands, mutually exclusive arguments, argument groups, and more.

Sub-commands

You can create sub-commands by creating a new instance of the ArgumentParser class and adding it as a subparser to the main parser:

subparsers = parser.add_subparsers(dest='command')

This command creates a subparser object and assigns it to the subparsers variable. You can add sub-commands to the subparser object:

hello_parser = subparsers.add_parser('hello', help='Say hello') hello_parser.add_argument('name', type=str, help='Name to greet')

This command adds a sub-command called hello to the parser. The sub-command expects a string argument called name.

Mutually Exclusive Arguments

You can make arguments mutually exclusive by adding them to an ArgumentGroup object:

group = parser.add_mutually_exclusive_group() group.add_argument('--verbose', action='store_true', help='Verbose output') group.add_argument('--quiet', action='store_true', help='Quiet output')

This command creates an argument group and adds two mutually exclusive arguments to it. The user can only specify one of these arguments.

Conclusion

Argparse is a powerful library that makes it easy to write command-line interfaces in Python. It provides many features that can help you create user-friendly and efficient programs. With this guide, you should have a good understanding of how to use argparse in Python.