如果有一个特定的参数，您只想装饰到组上，但根据需要适用于所有命令，您可以通过一些额外的管道来做到这一点，例如：
定制类：
import click
class GroupArgForCommands(click.Group):
"""Add special argument on group to front of command list"""
def __init__(self, *args, **kwargs):
super(GroupArgForCommands, self).__init__(*args, **kwargs)
cls = GroupArgForCommands.CommandArgument
# gather the special arguments
self._cmd_args = {
a.name: a for a in self.params if isinstance(a, cls)}
# strip out the special arguments
self.params = [a for a in self.params if not isinstance(a, cls)]
# hook the original add_command method
self._orig_add_command = click.Group.add_command.__get__(self)
class CommandArgument(click.Argument):
"""class to allow us to find our special arguments"""
@staticmethod
def command_argument(*param_decls, **attrs):
"""turn argument type into type we can find later"""
assert 'cls' not in attrs, "Not designed for custom arguments"
attrs['cls'] = GroupArgForCommands.CommandArgument
def decorator(f):
click.argument(*param_decls, **attrs)(f)
return f
return decorator
def add_command(self, cmd, name=None):
# hook add_command for any sub groups
if hasattr(cmd, 'add_command'):
cmd._orig_add_command = cmd.add_command
cmd.add_command = GroupArgForCommands.add_command.__get__(cmd)
cmd.cmd_args = self._cmd_args
# call original add_command
self._orig_add_command(cmd, name)
# if this command's callback has desired parameters add them
import inspect
args = inspect.signature(cmd.callback)
for arg_name in reversed(list(args.parameters)):
if arg_name in self._cmd_args:
cmd.params[:] = [self._cmd_args[arg_name]] + cmd.params
使用自定义类：
要使用自定义类，请传递cls参数到click.group()装饰器，使用@GroupArgForCommands.command_argument特殊参数的装饰器，然后根据需要向任何命令添加与特殊参数同名的参数。
@click.group(cls=GroupArgForCommands)
@GroupArgForCommands.command_argument('special')
def a_group():
"""My project description"""
@a_group.command()
def a_command(special):
"""a command under the group"""
这是如何运作的？
这有效是因为click是一个设计良好的OO框架。这@click.group()装饰器通常会实例化一个click.Group对象，但允许此行为被覆盖cls范围。所以继承是一件比较容易的事情click.Group在我们自己的班级中并超越所需的方法。
在这种情况下我们重写click.Group.add_command()这样，当添加命令时，我们可以检查命令回调参数，看看它们是否与我们的任何特殊参数具有相同的名称。如果它们匹配，则参数将添加到命令的参数中，就像直接对其进行修饰一样。
此外GroupArgForCommands实现了一个command_argument()方法。当添加特殊参数而不是使用时，此方法用作装饰器click.argument()
测试代码：
def process_path_to_project(ctx, cmd, value):
"""param callback example to convert path to project"""
# Use 'path' to construct a project.
# For this example we will just annotate and pass through
return 'converted {}'.format(value)
@click.group(cls=GroupArgForCommands)
@GroupArgForCommands.command_argument('path',
callback=process_path_to_project)
def dispatch():
"""My project description"""
@dispatch.command()
def serve(path):
"""Starts WSGI server using the configuration"""
click.echo('serve {}'.format(path))
@dispatch.group()
def config():
"""Validate or initalise a configuration file"""
pass
@config.command("validate")
def config_validate():
"""Reports on the validity of a configuration file"""
click.echo('config_validate')
@config.command("init")
def config_init(path):
"""Initialises a skeleton configuration file"""
click.echo('config_init {}'.format(path))
if __name__ == "__main__":
commands = (
'config init a_path',
'config init',
'config validate a_path',
'config validate',
'config a_path',
'config',
'serve a_path',
'serve',
'config init --help',
'config validate --help',
'',
)
import sys, time
time.sleep(1)
print('Click Version: {}'.format(click.__version__))
print('Python Version: {}'.format(sys.version))
for command in commands:
try:
time.sleep(0.1)
print('-----------')
print('> ' + command)
time.sleep(0.1)
dispatch(command.split())
except BaseException as exc:
if str(exc) != '0' and \
not isinstance(exc, (click.ClickException, SystemExit)):
raise
Results:
Click Version: 6.7
Python Version: 3.6.3 (v3.6.3:2c5fed8, Oct 3 2017, 18:11:49) [MSC v.1900 64 bit (AMD64)]
-----------
> config init a_path
config_init converted a_path
-----------
> config init
Usage: test.py config init [OPTIONS] PATH
Error: Missing argument "path".
-----------
> config validate a_path
Usage: test.py config validate [OPTIONS]
Error: Got unexpected extra argument (a_path)
-----------
> config validate
config_validate
-----------
> config a_path
Usage: test.py config [OPTIONS] COMMAND [ARGS]...
Error: No such command "a_path".
-----------
> config
Usage: test.py config [OPTIONS] COMMAND [ARGS]...
Validate or initalise a configuration file
Options:
--help Show this message and exit.
Commands:
init Initialises a skeleton configuration file
validate Reports on the validity of a configuration...
-----------
> serve a_path
serve converted a_path
-----------
> serve
Usage: test.py serve [OPTIONS] PATH
Error: Missing argument "path".
-----------
> config init --help
Usage: test.py config init [OPTIONS] PATH
Initialises a skeleton configuration file
Options:
--help Show this message and exit.
-----------
> config validate --help
Usage: test.py config validate [OPTIONS]
Reports on the validity of a configuration file
Options:
--help Show this message and exit.
-----------
>
Usage: test.py [OPTIONS] COMMAND [ARGS]...
My project description
Options:
--help Show this message and exit.
Commands:
config Validate or initalise a configuration file
serve Starts WSGI server using the configuration
