Python Click command doesn't recognize options

Question

I am trying to register command-line options in Click. Everything is working fine until I add the params argument to the constructor.

class InitCommand(click.Command):
 def __init__(self):
 super().__init__(
 name='init',
 short_help='Initialize the needed scaffolding.',
 help='something helpful, but longer',
 # params=[] ### <-- Works fine
 params=[click.Option('--force', default=False)]
 )

I get the following error:

Traceback (most recent call last):
 File "/usr/local/bin/aquapy", line 11, in <module>
 load_entry_point('aquapy-cli', 'console_scripts', 'aquapy')()
 File "/usr/local/lib/python3.6/site-packages/pkg_resources/__init__.py", line 561, in load_entry_point
 return get_distribution(dist).load_entry_point(group, name)
 File "/usr/local/lib/python3.6/site-packages/pkg_resources/__init__.py", line 2631, in load_entry_point
 return ep.load()
 File "/usr/local/lib/python3.6/site-packages/pkg_resources/__init__.py", line 2291, in load
 return self.resolve()
 File "/usr/local/lib/python3.6/site-packages/pkg_resources/__init__.py", line 2297, in resolve
 module = __import__(self.module_name, fromlist=['__name__'], level=0)
 File "/Users/******/__main__.py", line 3, in <module>
 from .bootstrap import main
 File "/Users/******/bootstrap.py", line 17, in <module>
 main.add_command(InitCommand())
 File "/Users/******/commands/init_command.py", line 10, in __init__
 params=[click.Option('--force', default=False)]
 File "/usr/local/lib/python3.6/site-packages/click/core.py", line 1460, in __init__
 Parameter.__init__(self, param_decls, type=type, **attrs)
 File "/usr/local/lib/python3.6/site-packages/click/core.py", line 1266, in __init__
 self._parse_decls(param_decls or (), expose_value)
 File "/usr/local/lib/python3.6/site-packages/click/core.py", line 1533, in _parse_decls
 raise TypeError('Name defined twice')
TypeError: Name defined twice

• Vaibhav Bajaj: You forgot a parenthesis in your __init__(). Also, please provide the complete Traceback. Thanks :).
• Dov Benyomin Sohacheski: No, I didn't...??
• Stephen Rauch: How about an MCVE and an explanation of the use case? The pattern you are using here to init this class looks nothing like the way click classes are generally used.
• Carcigenicate: @VaibhavBajaj The closing ) is at the bottom. The whole part under super() is the arguments to the constructor.

Answer 1

The issue is that click.Option() expects the first argument to a list and is not like the decorator version @click.option().

params=[click.Option(['--force'], default=False)]

Wrapping the command option in a list solved the problem.

• Kevin E: I figured it would behave like the decorator, too, and didn't even think to check the method signature in the Click documentation. Thanks!