updated more ch. 18 examples to Python 3.7

Author: ramalho

18-asyncio-py3.7/countdown.py

@@ -0,0 +1,30 @@
+#!/usr/bin/env python3
+
+# Inspired by
+# https://snarky.ca/how-the-heck-does-async-await-work-in-python-3-5/
+
+importasyncio
+importtime
+
+
+asyncdefcountdown(label, delay):
+tabs= (ord(label) -ord('A')) *'\t'
+n=3
+whilen>0:
+awaitasyncio.sleep(delay) # <----
+dt=time.perf_counter() -t0
+print('━'*50)
+print(f'{dt:7.4f}s \t{tabs}{label} = {n}')
+n-=1
+
+loop=asyncio.get_event_loop()
+tasks= [
+loop.create_task(countdown('A', .7)),
+loop.create_task(countdown('B', 2)),
+loop.create_task(countdown('C', .3)),
+loop.create_task(countdown('D', 1)),
+]
+t0=time.perf_counter()
+loop.run_until_complete(asyncio.wait(tasks))
+loop.close()
+print('━'*50)

18-asyncio-py3.7/spinner_asyncio.py

@@ -1,10 +1,12 @@
-# spinner_await.py
+#!/usr/bin/env python3
+
+# spinner_asyncio.py
 
 # credits: Example by Luciano Ramalho inspired by
 # Michele Simionato's multiprocessing example in the python-list:
 # https://mail.python.org/pipermail/python-list/2009-February/538048.html
 
-# BEGIN SPINNER_AWAIT
+# BEGIN SPINNER_ASYNCIO
 importasyncio
 importitertools
 importsys
@@ -18,31 +20,31 @@ async def spin(msg): # <1>
 flush()
 write('\x08'*len(status))
 try:
-awaitasyncio.sleep(.1) # <3>
-exceptasyncio.CancelledError: # <4>
+awaitasyncio.sleep(.1) # <2>
+exceptasyncio.CancelledError: # <3>
 break
 write(' '*len(status) +'\x08'*len(status))
 
 
-asyncdefslow_function(): # <5>
+asyncdefslow_function(): # <4>
 # pretend waiting a long time for I/O
-awaitasyncio.sleep(3) # <6>
+awaitasyncio.sleep(3) # <5>
 return42
 
 
-asyncdefsupervisor(): # <7>
-spinner=asyncio.create_task(spin('thinking!')) # <8>
-print('spinner object:', spinner) # <9>
-result=awaitslow_function() # <10>
-spinner.cancel() # <11>
+asyncdefsupervisor(): # <6>
+spinner=asyncio.create_task(spin('thinking!')) # <7>
+print('spinner object:', spinner) # <8>
+result=awaitslow_function() # <9>
+spinner.cancel() # <10>
 returnresult
 
 
 defmain():
-result=asyncio.run(supervisor()) # <12>
+result=asyncio.run(supervisor()) # <11>
 print('Answer:', result)
 
 
 if__name__=='__main__':
 main()
-# END SPINNER_AWAIT
+# END SPINNER_ASYNCIO

18-asyncio-py3.7/spinner_curio.py

@@ -1,3 +1,5 @@
+#!/usr/bin/env python3
+
 # spinner_thread.py
 
 # credits: Adapted from Michele Simionato's