I am trying to feed a dictionary by using .send(). And my code snippet is below
def coroutine(func):
def start(*args, **kwargs):
cr = func(*args, **kwargs)
next(cr)
return cr
return start
@coroutine
def putd(di):
print("via coroutines adding a key : value to dictionary")
try:
item = yield
for key, value in item.items():
if key in di:
print("Key : {0} already exists".format(key))
else:
di[key] = value
print(di)
except StopIteration :
print("yield frame got closed")
di = {}
gobj = putd(di)
gobj.send({"plan" : "shuttle"})
gobj.close()
And I believe I am handling the exception properly but still I am getting StopIteration exception.
scratch.py
Traceback (most recent call last):
via coroutines adding a key : value to dictionary
{'plan': 'shuttle'}
File "scratch.py", line 39, in <module>
gobj.send({"plan" : "shuttle"})
StopIteration
Process finished with exit code 1
Am I not handling that exception properly or am I missing something ? ANy help greatly appreciated.
Your coroutine exits after first send/yield. That generates a StopIteration and you cannot handle it in the coroutine itself, but only when invoking send. From the docs:
The send() method returns the next value yielded by the generator, or raises StopIteration if the generator exits without yielding another value.
@coroutine
def putd(di):
print("via coroutines adding a key : value to dictionary")
try:
item = yield
for key, value in item.items():
if key in di:
print("Key : {0} already exists".format(key))
else:
di[key] = value
print(di)
except StopIteration :
print("yield frame got closed")
# here is an implicit return None which terminates the coroutine
I guess you want to keep the coroutine alive accepting as many sends as you want until an explicit close:
@coroutine
def putd(di):
print("via coroutines adding a key : value to dictionary")
try:
while True:
item = yield
for key, value in item.items():
if key in di:
print("Key : {0} already exists".format(key))
else:
di[key] = value
print(di)
except GeneratorExit:
print("yield frame got closed")
Please note that now the GeneratorExit exception is caught.