click option

https://click.palletsprojects.com/en/7.x/options/

Name Your Options

A name is chosen in the following order

1. If a name is not prefixed, it is used as the Python argument name and not treated as an option name on the command line.

2. If there is at least one name prefixed with two dashes, the first one given is used as the name.

3. The first name prefixed with one dash is used otherwise.

@click.command()
@click.option('-s', '--string-to-echo')
def echo(string_to_echo):
    click.echo(string_to_echo)

@click.command()
@click.option('-s', '--string-to-echo', 'string')
def echo(string):
    click.echo(string)

可以用單-,也可用雙--,也可以不用,三者會選擇一個作爲最終變量

“-f”, “–foo-bar”, the name is foo_bar
“-x”, the name is x
“-f”, “–filename”, “dest”, the name is dest
“–CamelCase”, the name is camelcase
“-f”, “-fb”, the name is f
“–f”, “–foo-bar”, the name is f
“—f”, the name is _f

Basic Value Options

default來設置默認值

@click.command()
@click.option('--n', default=1)
def dots(n):
    click.echo('.' * n)

requirement來設置該參數是必須填寫的,type來設置參數的類型,如果不設置默認是str

# How to make an option required
@click.command()
@click.option('--n', required=True, type=int)
def dots(n):
    click.echo('.' * n)

使用_來避免保留字衝突,from是python的保留字,所以要使用_來區別

# How to use a Python reserved word such as `from` as a parameter
@click.command()
@click.option('--from', '-f', 'from_')
@click.option('--to', '-t')
def reserved_param_name(from_, to):
    click.echo('from %s to %s' % (from_, to))

通過show_default參數來默認輸出幫助信息的默認值

@click.command()
@click.option('--n', default=1, show_default=True)
def dots(n):
    click.echo('.' * n)

$ dots --help
Usage: dots [OPTIONS]

Options:
  --n INTEGER  [default: 1]
  --help       Show this message and exit.

nargs來傳入多個參數

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

$ findme --pos 2.0 3.0
2.0 / 3.0

元組類型

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

本質上做了如下的操作

@click.command()
@click.option('--item', nargs=2, type=click.Tuple([str, int]))
def putitem(item):
    click.echo('name=%s id=%d' % item)

Multiple Options

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

$ commit -m foo -m bar
foo
bar

Counting

Boolean Flags

import sys

@click.command()
@click.option('--shout/--no-shout', default=False)
def info(shout):
    rv = sys.platform
    if shout:
        rv = rv.upper() + '!!!!111'
    click.echo(rv)

$ info --shout
LINUX!!!!111
$ info --no-shout
linux

Choice Options

規定值可選

@click.command()
@click.option('--hash-type',
              type=click.Choice(['MD5', 'SHA1'], case_sensitive=False))
def digest(hash_type):
    click.echo(hash_type)

Prompting

用戶輸入

@click.command()
@click.option('--name', prompt=True)
def hello(name):
    click.echo('Hello %s!' % name)

$ hello --name=John
Hello John!
$ hello
Name: John
Hello John!

Password Prompts
Dynamic Defaults for Prompts

Callbacks and Eager Options

將某個參數指定調用的方法

def print_version(ctx, param, value):
    if not value or ctx.resilient_parsing:
        return
    click.echo('Version 1.0')
    ctx.exit()

@click.command()
@click.option('--version', is_flag=True, callback=print_version,
              expose_value=False, is_eager=True)
def hello():
    click.echo('Hello World!')

Yes Parameters

樣用戶確認操作

def abort_if_false(ctx, param, value):
    if not value:
        ctx.abort()

@click.command()
@click.option('--yes', is_flag=True, callback=abort_if_false,
              expose_value=False,
              prompt='Are you sure you want to drop the db?')
def dropdb():
    click.echo('Dropped all tables!')

Values from Environment Variables

@click.command()
@click.option('--username')
def greet(username):
    click.echo('Hello %s!' % username)

if __name__ == '__main__':
    greet(auto_envvar_prefix='GREETER')