extmod/asyncio: Make SingletonGenerator create_task()-aware.

jjsuwa-sys3175 · jjsuwa-sys3175 · commit 3ca0ed30d124 · 2025-01-27T16:55:26.000+09:00
This commit allows the awaitable returned by asyncio.sleep/sleep_ms()
to be passed directly to asyncio.create_task().

Although the documentation says that sleep/sleep_ms() are coroutines and
create_task() accepts coroutines, this is not the case; sleep/sleep_ms()
actually return a SingletonGenerator(), which is missing a send() method.

&gt; === import asyncio
&gt; === asyncio.run(asyncio.sleep_ms(2000))
&gt; ===
&gt; Traceback (most recent call last):
&gt;   File "&lt;stdin&gt;", line 3, in &lt;module&gt;
&gt;   File "asyncio/core.py", line 1, in run
&gt;   File "asyncio/core.py", line 1, in create_task
&gt; TypeError: coroutine expected

This is easily solved by implementing the missing send() method:

&gt; === import asyncio
&gt; === from time import ticks_ms as ticks, ticks_add
&gt; ===
&gt; === class SingletonGenerator2(asyncio.SingletonGenerator):
&gt; ===   def send(self, x):
&gt; ===     self.__next__()
&gt; ===
&gt; === def sleep_ms(t, sgen=SingletonGenerator2()):
&gt; ===   sgen.state = ticks_add(ticks(), max(0, t))
&gt; ===   return sgen
&gt; ===
&gt; === asyncio.run(sleep_ms(2000))
&gt; ===
&gt; &gt;&gt;&gt;
diff --git a/extmod/asyncio/core.py b/extmod/asyncio/core.py
@@ -49,6 +49,9 @@ def __next__(self):
             self.exc.__traceback__ = None
             raise self.exc
 
+    def send(self, x):
+        self.__next__()
+
 
 # Pause task execution for the given time (integer in milliseconds, uPy extension)
 # Use a SingletonGenerator to do it without allocating on the heap
