单击:如何将操作应用于所有命令和子命令，但允许选择退出? [英] Click: how do I apply an action to all commands and subcommands but allow a command to opt-out?
问题描述
在某些情况下，我想为我的大多数点击命令和子命令自动运行一个通用功能check_upgrade()，但是在某些情况下，我不想运行它.我当时想我可以有一个装饰器，可以为不应该运行check_upgrade()的命令添加(例如@bypass_upgrade_check).
I have a case where I'd like to automatically run a common function, check_upgrade(), for most of my click commands and sub-commands, but there are a few cases where I don't want to run it. I was thinking I could have a decorator that one can add (e.g. @bypass_upgrade_check) for commands where check_upgrade() should not run.
我希望获得类似的东西(感谢斯蒂芬·劳赫的初衷):
I was hoping for something like (thanks Stephen Rauch for the initial idea):
def do_upgrade():
print "Performing upgrade"
def bypass_upgrade_check(func):
setattr(func, "do_upgrade_check", False)
return func
@click.group()
@click.pass_context
def common(ctx):
sub_cmd = ctx.command.commands[ctx.invoked_subcommand]
if getattr(sub_cmd, "do_upgrade_check", True):
do_upgrade()
@bypass_upgrade_check
@common.command()
def top_cmd1():
# don't run do_upgrade() on top level command
pass
@common.command()
def top_cmd2():
# DO run do_upgrade() on top level command
pass
@common.group()
def sub_cmd_group():
pass
@bypass_upgrade_check
@sub_cmd.command()
def sub_cmd1():
# don't run do_upgrade() on second-level command
pass
@sub.command()
def sub_cmd2():
# DO run do_upgrade() on second-level command
pass
不幸的是，这仅适用于顶级命令，因为ctx.invoked_subcommand是指sub_cmd_group而不是sub_cmd1或sub_cmd2.
Unfortunately, this only works for the top-level commands, since ctx.invoked_subcommand refers to sub_cmd_group and not sub_cmd1 or sub_cmd2.
是否有一种方法可以递归地搜索子命令，或者使用自定义组来使用顶级命令和子命令来实现此功能?
Is there a way to recursively search through sub-commands, or perhaps using a custom Group to be able to achieve this functionality with both top-level commands as well as subcommands?
推荐答案
一种解决方法是构建与自定义click.Group类配对的自定义装饰器:
One way to solve this is to build a custom decorator that pairs with a custom click.Group class:
def make_exclude_hook_group(callback):
""" for any command that is not decorated, call the callback """
hook_attr_name = 'hook_' + callback.__name__
class HookGroup(click.Group):
""" group to hook context invoke to see if the callback is needed"""
def invoke(self, ctx):
""" group invoke which hooks context invoke """
invoke = ctx.invoke
def ctx_invoke(*args, **kwargs):
""" monkey patched context invoke """
sub_cmd = ctx.command.commands[ctx.invoked_subcommand]
if not isinstance(sub_cmd, click.Group) and \
getattr(sub_cmd, hook_attr_name, True):
# invoke the callback
callback()
return invoke(*args, **kwargs)
ctx.invoke = ctx_invoke
return super(HookGroup, self).invoke(ctx)
def group(self, *args, **kwargs):
""" new group decorator to make sure sub groups are also hooked """
if 'cls' not in kwargs:
kwargs['cls'] = type(self)
return super(HookGroup, self).group(*args, **kwargs)
def decorator(func=None):
if func is None:
# if called other than as decorator, return group class
return HookGroup
setattr(func, hook_attr_name, False)
return decorator
使用装饰器生成器:
要使用装饰器，我们首先需要构建装饰器，例如:
Using the decorator builder:
To use the decorator we first need to build the decorator like:
bypass_upgrade_check = make_exclude_hook_group(do_upgrade)
然后我们需要将其用作click.group()的自定义类，例如:
Then we need to use it as a custom class to click.group() like:
@click.group(cls=bypass_upgrade_check())
...
最后，我们可以为不需要使用回调的组装饰任何命令或子命令，例如:
And finally, we can decorate any commands or sub-commands to the group that need to not use the callback like:
@bypass_upgrade_check
@my_group.command()
def my_click_command_without_upgrade():
...
这是如何工作的?
之所以有用，是因为click是一个设计良好的OO框架. @click.group()装饰器通常会实例化click.Group对象，但允许使用cls参数覆盖此行为.因此，在我们自己的类中从click.Group继承并超越所需的方法是相对容易的事情.
How does this work?
This works because click is a well designed OO framework. The @click.group() decorator usually instantiates a click.Group object but allows this behavior to be over-ridden with the cls parameter. So it is a relatively easy matter to inherit from click.Group in our own class and over ride the desired methods.
在这种情况下，我们构建了一个装饰器，该装饰器在不需要调用回调的任何click函数上设置属性.然后，在我们的自定义组中，我们对上下文进行补丁click.Context.invoke()，如果要执行的命令尚未修饰，则调用回调.
In this case, we build a decorator that sets an attribute on any click function that does not need the callback called. Then in our custom group, we monkey patch click.Context.invoke() of our context and if the command that is about to be executed has not been decorated, we call the callback.
import click
def do_upgrade():
print("Performing upgrade")
bypass_upgrade_check = make_exclude_hook_group(do_upgrade)
@click.group(cls=bypass_upgrade_check())
@click.pass_context
def cli(ctx):
pass
@bypass_upgrade_check
@cli.command()
def top_cmd1():
click.echo('cmd1')
@cli.command()
def top_cmd2():
click.echo('cmd2')
@cli.group()
def sub_cmd_group():
click.echo('sub_cmd_group')
@bypass_upgrade_check
@sub_cmd_group.command()
def sub_cmd1():
click.echo('sub_cmd1')
@sub_cmd_group.command()
def sub_cmd2():
click.echo('sub_cmd2')
if __name__ == "__main__":
commands = (
'top_cmd1',
'top_cmd2',
'sub_cmd_group sub_cmd1',
'sub_cmd_group sub_cmd2',
'--help',
)
import sys, time
time.sleep(1)
print('Click Version: {}'.format(click.__version__))
print('Python Version: {}'.format(sys.version))
for cmd in commands:
try:
time.sleep(0.1)
print('-----------')
print('> ' + cmd)
time.sleep(0.1)
cli(cmd.split())
except BaseException as exc:
if str(exc) != '0' and \
not isinstance(exc, (click.ClickException, SystemExit)):
raise
结果:
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)]
-----------
> top_cmd1
cmd1
-----------
> top_cmd2
Performing upgrade
cmd2
-----------
> sub_cmd_group sub_cmd1
sub_cmd_group
sub_cmd1
-----------
> sub_cmd_group sub_cmd2
Performing upgrade
sub_cmd_group
sub_cmd2
-----------
> --help
Usage: test.py [OPTIONS] COMMAND [ARGS]...
Options:
--help Show this message and exit.
Commands:
sub_cmd_group
top_cmd1
top_cmd2
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