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#!/usr/bin/env python
"""An example cmd2 mixin."""
import functools
from collections.abc import Callable
from typing import TYPE_CHECKING
import cmd2
if TYPE_CHECKING: # pragma: no cover
_Base = cmd2.Cmd
else:
_Base = object
def empty_decorator(func: Callable) -> Callable:
"""An empty decorator for use with your mixin."""
@functools.wraps(func)
def _empty_decorator(self, *args, **kwargs) -> None:
self.poutput("in the empty decorator")
func(self, *args, **kwargs)
_empty_decorator.__doc__ = func.__doc__
return _empty_decorator
class MyMixin(_Base):
"""A mixin class which adds a 'say' command to a cmd2 subclass.
The order in which you add the mixin matters. Say you want to
use this mixin in a class called MyApp.
class MyApp(MyMixin, cmd2.Cmd):
def __init__(self, *args, **kwargs):
# gotta have this or neither the mixin or cmd2 will initialize
super().__init__(*args, **kwargs)
"""
def __init__(self, *args, **kwargs) -> None:
# code placed here runs before cmd2 initializes
super().__init__(*args, **kwargs)
# code placed here runs after cmd2 initializes
# this is where you register any hook functions
self.register_preloop_hook(self.cmd2_mymixin_preloop_hook)
self.register_postloop_hook(self.cmd2_mymixin_postloop_hook)
self.register_postparsing_hook(self.cmd2_mymixin_postparsing_hook)
def do_say(self, statement) -> None:
"""Simple say command."""
self.poutput(statement)
#
# define hooks as functions, not methods
def cmd2_mymixin_preloop_hook(self) -> None:
"""Method to be called before the command loop begins."""
self.poutput("preloop hook")
def cmd2_mymixin_postloop_hook(self) -> None:
"""Method to be called after the command loop finishes."""
self.poutput("postloop hook")
def cmd2_mymixin_postparsing_hook(self, data: cmd2.plugin.PostparsingData) -> cmd2.plugin.PostparsingData:
"""Method to be called after parsing user input, but before running the command."""
self.poutput('in postparsing hook')
return data
class Example(MyMixin, cmd2.Cmd):
"""An class to show how to use a mixin."""
def __init__(self, *args, **kwargs) -> None:
# gotta have this or neither the mixin or cmd2 will initialize
super().__init__(*args, **kwargs)
@empty_decorator
def do_something(self, _arg) -> None:
self.poutput('this is the something command')
if __name__ == '__main__':
app = Example()
app.cmdloop()
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