click命令行工具使用详解

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click简介

click是类似docopt的命令行工具，让我们可以快速的创建一个命令行工具，并且click能让我用尽量少的代码，并自动生成命令行帮助文档

正如官网所说，click有三大特性：

  • arbitrary nesting of commands
  • automatic help page generation
  • supports lazy loading of subcommands at runtime

click基本使用

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import click
@click.command()
@click.option('--count', default=1, help='Number of greetings.')
@click.option('--name', prompt='Your name',
              help='The person to greet.')
def hello(count, name):
    """Simple program that greets NAME for a total of COUNT times."""
    for x in range(count):
        click.echo('Hello %s!' % name)
if __name__ == '__main__':
    hello()

我在cmd中运行如下：

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F:\cookies\python\learnPython\5_常用模块\click>python 1_基本使用.py
Your name: zzx
Hello zzx!
F:\cookies\python\learnPython\5_常用模块\click>python 1_基本使用.py --help
Usage: 1_基本使用.py [OPTIONS]
  Simple program that greets NAME for a total of COUNT times.
Options:
  --count INTEGER  Number of greetings.
  --name TEXT      The person to greet.
  --help           Show this message and exit.
F:\cookies\python\learnPython\5_常用模块\click>

基本概念

click是基于装饰器的，我们可以在方法上使用click.command()装饰器来将该方法变成一个命令行工具

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import click
@click.command()
def hello():
    click.echo('Hello World!')
if __name__ == '__main__':
    hello()
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$ python hello.py
Hello World!
$ python hello.py --help
Usage: hello.py [OPTIONS]
Options:
  --help  Show this message and exit.

echo()

之所以不使用print()是为了兼容python2和3，当然也是可以使用print()的

嵌套命令

可以通过group来实现命令行的嵌套，也就是让一个命令行工具具有多个命令

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import click
@click.group()
def cli():
    click.echo('Hello world')
@cli.command()
def initdb():
    click.echo('Initialized the database')
@cli.command()
def dropdb():
    click.echo('Dropped the database')
if __name__ == '__main__':
    cli()
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F:\cookies\python\learnPython\5_常用模块\click>python 2_group.py --help
Usage: 2_group.py [OPTIONS] COMMAND [ARGS]...
Options:
  --help  Show this message and exit.
Commands:
  dropdb
  initdb
F:\cookies\python\learnPython\5_常用模块\click>python 2_group.py initdb
Hello world
Initialized the database
F:\cookies\python\learnPython\5_常用模块\click>python 2_group.py dropdb
Hello world
Dropped the database

parameter

@click.argument()可以给命令添加参数

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import click
@click.command()
@click.option('--count', default=1, help='number of greetings')
@click.argument('name')
def hello(count, name):
    for x in range(count):
        click.echo('Hello %s!' % name)
if __name__ == '__main__':
    hello()
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F:\cookies\python\learnPython\5_常用模块\click>python 3_argument.py
Usage: 3_argument.py [OPTIONS] NAME
Error: Missing argument "name".
F:\cookies\python\learnPython\5_常用模块\click>python 3_argument.py --help
Usage: 3_argument.py [OPTIONS] NAME
Options:
  --count INTEGER  number of greetings
  --help           Show this message and exit.
F:\cookies\python\learnPython\5_常用模块\click>python 3_argument.py zzx
Hello zzx!

parameter包括arguments和options，arguments一般是必须的，而options一般是可选的

parameter类型

  • click.STRING：默认类型
  • click.INT：int
  • click.FLOAT：float
  • click.BOOL：boolean
  • click.File(mode=’r’, encoding=None, errors=’strict’, lazy=None, atomic=False)
  • click.Path(exists=False, file_okay=True, dir_okay=True, writable=False, readable=True, resolve_path=False, allow_dash=False, path_type=None)
  • click.Choice(choices)
  • click.IntRange(min=None, max=None, clamp=False)

File Arguments

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@click.command()
@click.argument('input', type=click.File('rb'))
@click.argument('output', type=click.File('wb'))
def inout(input, output):
    while True:
        chunk = input.read(1024)
        if not chunk:
            break
        output.write(chunk)

File Path Arguments

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@click.command()
@click.argument('f', type=click.Path(exists=True))
def touch(f):
    click.echo(click.format_filename(f))

Choice Options

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@click.command()
@click.option('--hash-type', type=click.Choice(['md5', 'sha1']))
def digest(hash_type):
    click.echo(hash_type)
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$ digest --hash-type=md5
md5
$ digest --hash-type=foo
Usage: digest [OPTIONS]
Error: Invalid value for "--hash-type": invalid choice: foo. (choose from md5, sha1)
$ digest --help
Usage: digest [OPTIONS]
Options:
  --hash-type [md5|sha1]
  --help                  Show this message and exit.

Range Options

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@click.command()
@click.option('--count', type=click.IntRange(0, 20, clamp=True))
@click.option('--digit', type=click.IntRange(0, 10))
def repeat(count, digit):
    click.echo(str(digit) * count)
if __name__ == '__main__':
    repeat()
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$ repeat --count=1000 --digit=5
55555555555555555555
$ repeat --count=1000 --digit=12
Usage: repeat [OPTIONS]
Error: Invalid value for "--digit": 12 is not in the valid range of 0 to 10.

Options

Multi Value Options

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@click.command()
@click.option('--pos', nargs=2, type=float)
def findme(pos):
    click.echo('%s / %s' % pos)

Tuples as Multi Value Options

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@click.command()
@click.option('--item', type=(unicode, int))
def putitem(item):
    click.echo('name=%s id=%d' % item)

Multiple Options

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@click.command()
@click.option('--message', '-m', multiple=True)
def commit(message):
    click.echo('\n'.join(message))
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$ commit -m foo -m bar
foo
bar

Arguments

Variadic Arguments

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@click.command()
@click.argument('src', nargs=-1)
@click.argument('dst', nargs=1)
def copy(src, dst):
    for fn in src:
        click.echo('move %s to folder %s' % (fn, dst))

nargs=-1表示参数数目无限制

User Input Prompts

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value = click.prompt('Please enter a valid integer', type=int)
value = click.prompt('Please enter a number', default=42.0)
if click.confirm('Do you want to continue?'):
    click.echo('Well done!')

其他功能

click还有测试模块，以及输出带样式的文本等，在此就不详细介绍了

参考文档

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