Decorator to async function python - python-asyncio

Question

A simple decorate to calculate time a function takes to run:
import time
def decor(f):
starttime=time.time()
f()
print("child functoin run time is ", (time.time()-starttime)*1000, "ms")
return f
try to use it to decorate async functions:
async def sleep_and_print(seconds):
print(f"starting async {seconds} sleep 😴")
await asyncio.sleep(seconds)
print(f"finished async {seconds} sleep ⏰")
return seconds
#decor
async def main():
# using arguments
results = await asyncio.gather(sleep_and_print(3), sleep_and_print(6))
print(results)
asyncio.run(main())
I got RuntimeWarning: coroutine 'main' was never awaited error
If I change the decorator function to async and await, eg
async def decor(f):
starttime=time.time()
await f()
print("child functoin run time is ", (time.time()-starttime)*1000, "ms")
return f
asyncio.run(main()) failed with coroutine' object is not callable
Why main() becomes uncallable? Any suggestion on the work around?

Answer 1

Try to return async function from the decorator function:
import time
import asyncio
def decor(f):
async def _fn():
starttime = time.time()
await f()
print(
"child function run time is ",
(time.time() - starttime) * 1000,
"ms",
)
return _fn
async def sleep_and_print(seconds):
print(f"starting async {seconds} sleep 😴")
await asyncio.sleep(seconds)
print(f"finished async {seconds} sleep ⏰")
return seconds
#decor
async def main():
# using arguments
results = await asyncio.gather(sleep_and_print(3), sleep_and_print(6))
print(results)
asyncio.run(main())
Prints:
starting async 3 sleep 😴
starting async 6 sleep 😴
finished async 3 sleep ⏰
finished async 6 sleep ⏰
[3, 6]
child function run time is 6002.1820068359375 ms