如何在Windows 11中以asyncio模式运行ptpython？

问题背景 #

在Windows 11上使用Python 3.12.3（Python 3.8.10测试也存在相同问题）时，系统内置的asyncio REPL可以正常运行：

PS C:\> python -m asyncio
asyncio REPL 3.12.3 (tags/v3.12.3:f6650f9, Apr  9 2024, 14:05:25) [MSC v.1938 64 bit (AMD64)] on win32
Use "await" directly instead of "asyncio.run()".
Type "help", "copyright", "credits" or "license" for more information.
>>> import asyncio
>>> await asyncio.sleep(1, 'Done!')
'Done!'
>>> exit()

但通过ptpython --asyncio启动异步REPL后，执行await语句会抛出NotImplementedError和NameError：

C:\> ptpython --asyncio
Starting ptpython asyncio REPL
Use "await" directly instead of "asyncio.run()".
In [1]: await asyncio.sleep(1, 'Done!')
Traceback (most recent call last):
  File "c:\users\james\appdata\local\programs\python\python38-32\lib\site-packages\ptpython\repl.py", line 183, in run_and_show_expression_async
    loop.add_signal_handler(signal.SIGINT, lambda *_: task.cancel())
  File "c:\users\james\appdata\local\programs\python\python38-32\lib\asyncio\events.py", line 536, in add_signal_handler
    raise NotImplementedError
NotImplementedError

Traceback (most recent call last):
  File "c:\users\james\appdata\local\programs\python\python38-32\lib\runpy.py", line 194, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "c:\users\james\appdata\local\programs\python\python38-32\lib\runpy.py", line 87, in _run_code
    exec(code, run_globals)
  File "C:\users\james\appdata\local\Programs\Python\Python38-32\Scripts\ptpython.exe\__main__.py", line 7, in <module>
  File "c:\users\james\appdata\local\programs\python\python38-32\lib\site-packages\ptpython\entry_points\run_ptpython.py", line 231, in run
    asyncio.run(embed_result)
  File "c:\users\james\appdata\local\programs\python\python38-32\lib\asyncio\runners.py", line 44, in run
    return loop.run_until_complete(main)
  File "c:\users\james\appdata\local\programs\python\python38-32\lib\asyncio\base_events.py", line 616, in run_until_complete
    return future.result()
  File "c:\users\james\appdata\local\programs\python\python38-32\lib\site-packages\ptpython\repl.py", line 528, in coroutine
    await repl.run_async()
  File "c:\users\james\appdata\local\programs\python\python38-32\lib\site-packages\ptpython\repl.py", line 252, in run_async
    await self.run_and_show_expression_async(text)
  File "c:\users\james\appdata\local\programs\python\python38-32\lib\site-packages\ptpython\repl.py", line 206, in run_and_show_expression_async
    loop.remove_signal_handler(signal.SIGINT)
  File "c:\users\james\appdata\local\programs\python\python38-32\lib\asyncio\events.py", line 539, in remove_signal_handler
    raise NotImplementedError
NotImplementedError
Task exception was never retrieved
future: <Task finished name='Task-61' coro=<PythonRepl.run_and_show_expression_async.<locals>.eval() done, defined at c:\users\james\appdata\local\programs\python\python38-32\lib\site-packages\ptpython\repl.py:172> exception=NameError("name 'asyncio' is not defined")>
Traceback (most recent call last):
  File "c:\users\james\appdata\local\programs\python\python38-32\lib\site-packages\ptpython\repl.py", line 175, in eval
    return await self.eval_async(text)
  File "c:\users\james\appdata\local\programs\python\python38-32\lib\site-packages\ptpython\repl.py", line 329, in eval_async
    result = await result
  File "<stdin>", line 1, in <module>
NameError: name 'asyncio' is not defined

现有临时解决方法（来自@jupiterbjy）：

PS C:\> ptpython
>>> import asyncio
>>> async def main():
...     return await asyncio.sleep(1, 'Done!')
...
>>> print(asyncio.run(main()))
Done!
>>> exit()

错误原因 #

1. NotImplementedError：Windows系统不支持asyncio的add_signal_handler和remove_signal_handler方法（这两个方法是Unix平台专属），但ptpython的asyncio REPL代码未做平台兼容判断，直接调用导致报错。
2. NameError：由于上述报错中断了初始化流程，asyncio模块未被自动导入，而系统内置REPL会自动完成asyncio的导入。

解决方法 #

方法1：修改ptpython源码添加平台兼容 #

找到ptpython安装目录下的repl.py（路径示例：C:\Users\<你的用户名>\AppData\Local\Programs\Python\Python3x\Lib\site-packages\ptpython\repl.py），定位到run_and_show_expression_async函数，添加平台判断跳过Windows不支持的信号处理逻辑：

# 在文件顶部导入sys模块（如果没有的话）
import sys
import signal
import asyncio

# ...

async def run_and_show_expression_async(self, text: str) -> None:
    # ... 保留原有代码 ...
    loop = asyncio.get_running_loop()
    # 新增：仅在非Windows平台添加信号处理
    if sys.platform != 'win32':
        loop.add_signal_handler(signal.SIGINT, lambda *_: task.cancel())
    try:
        result = await task
    except asyncio.CancelledError:
        self._handle_keyboard_interrupt()
        return
    finally:
        # 新增：仅在非Windows平台移除信号处理
        if sys.platform != 'win32':
            loop.remove_signal_handler(signal.SIGINT)
    # ... 保留原有代码 ...

方法2：通过ptpython配置文件实现兼容 #

创建ptpython配置文件（Windows路径：C:\Users\<你的用户名>\.ptpython\config.py，如果目录不存在则手动创建），添加以下内容：

import asyncio
import sys
import signal
from ptpython.repl import PythonRepl

def configure(repl: PythonRepl) -> None:
    # 自动导入asyncio，避免NameError
    repl.auto_imports.add('asyncio')
    
    # 重写异步执行方法，跳过Windows信号处理
    original_run = repl.run_and_show_expression_async
    
    async def patched_run(text: str) -> None:
        loop = asyncio.get_running_loop()
        original_handler = None
        
        # 仅在非Windows平台处理信号
        if sys.platform != 'win32':
            try:
                original_handler = loop.get_signal_handler(signal.SIGINT)
                loop.add_signal_handler(signal.SIGINT, lambda *_: asyncio.current_task().cancel())
            except Exception:
                pass
        
        try:
            await original_run(text)
        finally:
            # 恢复原有信号处理（如果存在）
            if sys.platform != 'win32' and original_handler is not None:
                loop.add_signal_handler(signal.SIGINT, original_handler)
            elif sys.platform != 'win32':
                loop.remove_signal_handler(signal.SIGINT)
    
    repl.run_and_show_expression_async = patched_run

之后运行ptpython --asyncio即可正常使用await语句。

方法3：升级ptpython到最新版本 #

尝试升级ptpython，检查官方是否已修复Windows平台的兼容问题：

pip install --upgrade ptpython

内容的提问来源于stack exchange，提问作者James S.