交互式调试

Interactive debugging

中文

当你启动一个交互式 Python 会话来调试任何异步程序（无论是基于 asyncio 、Trio 还是其他框架），每个 await 表达式都需要在异步函数内：

$ python
Python 3.10.6
Type "help", "copyright", "credits" or "license" for more information.
>>> import trio
>>> await trio.sleep(1)
File "<stdin>", line 1
SyntaxError: 'await' outside function
>>> async def main():
...     print("hello...")
...     await trio.sleep(1)
...     print("world!")
...
>>> trio.run(main)
hello...
world!

这可能会让你很难快速迭代，因为每次进行修改时，你都必须重新定义整个函数体。

Trio 提供了一个修改过的交互式控制台，允许你在顶层直接使用 await。你可以通过运行 python -m trio 来访问这个控制台：

$ python -m trio
Trio 0.21.0+dev, Python 3.10.6
Use "await" directly instead of "trio.run()".
Type "help", "copyright", "credits" or "license" for more information.
>>> import trio
>>> print("hello..."); await trio.sleep(1); print("world!")
hello...
world!

如果你是 IPython 用户，你可以使用 IPython 的 autoawait 功能。你可以通过在 IPython shell 中运行魔法命令 %autoawait trio 来启用它。要在每次安装 Trio 时都启用 autoawait，你可以将以下内容添加到你的 IPython 启动文件中。 （例如 ~/.ipython/profile_default/startup/10-async.py）

try:
   import trio
   get_ipython().run_line_magic("autoawait", "trio")
except ImportError:
   pass

英文

When you start an interactive Python session to debug any async program (whether it's based on asyncio, Trio, or something else), every await expression needs to be inside an async function:

$ python
Python 3.10.6
Type "help", "copyright", "credits" or "license" for more information.
>>> import trio
>>> await trio.sleep(1)
File "<stdin>", line 1
SyntaxError: 'await' outside function
>>> async def main():
...     print("hello...")
...     await trio.sleep(1)
...     print("world!")
...
>>> trio.run(main)
hello...
world!

This can make it difficult to iterate quickly since you have to redefine the whole function body whenever you make a tweak.

Trio provides a modified interactive console that lets you await at the top level. You can access this console by running python -m trio:

$ python -m trio
Trio 0.21.0+dev, Python 3.10.6
Use "await" directly instead of "trio.run()".
Type "help", "copyright", "credits" or "license" for more information.
>>> import trio
>>> print("hello..."); await trio.sleep(1); print("world!")
hello...
world!

If you are an IPython user, you can use IPython's autoawait function. This can be enabled within the IPython shell by running the magic command %autoawait trio. To have autoawait enabled whenever Trio installed, you can add the following to your IPython startup files. (e.g. ~/.ipython/profile_default/startup/10-async.py)

try:
   import trio
   get_ipython().run_line_magic("autoawait", "trio")
except ImportError:
   pass