Add "usage" command demo

demo/plugins/tuling.py

@@ -3,6 +3,13 @@ from nonebot import (
     on_natural_language, NLPSession, NLPResult
 )
 
+__plugin_name__ = '智能聊天'
+__plugin_usage__ = r"""
+智能聊天功能使用帮助
+
+直接跟我聊天即可～
+""".strip()
+
 
 @on_command('tuling', aliases=('聊天', '对话'))
 async def tuling(session: CommandSession):

demo/plugins/usage.py

@@ -0,0 +1,14 @@
+import nonebot
+from nonebot import on_command, CommandSession
+
+
+@on_command('usage', aliases=['使用帮助', '帮助', '使用方法'])
+async def _(session: CommandSession):
+    plugins = list(filter(lambda p: p.name, nonebot.get_loaded_plugins()))
+    arg = session.current_arg_text.strip().lower()
+    if not arg:
+        session.finish(
+            '我现在支持的功能有：\n\n' + '\n'.join(p.name for p in plugins))
+    for p in plugins:
+        if p.name.lower() == arg:
+            await session.send(p.usage)

demo/plugins/weather/__init__.py

@@ -6,6 +6,13 @@ from nonebot.helpers import render_expression as __
 
 from . import expressions as e
 
+__plugin_name__ = '天气'
+__plugin_usage__ = r"""
+天气功能使用帮助
+
+天气  [城市名称]
+""".strip()
+
 w = CommandGroup('weather')