[Python] Why does the output change after putting code in a function in a simpy process?

In a simpy process I handle a simpy interrupt. I do this in two places and so I want to put the handling code in a function. Before putting it in a function all functions well, after putting it in a function it yields different results.

Below the written out code

def offer(env, simpy_car, simpy_tankcar, route, timestep):
action = None
t_prev = -1
for lat in route:
try:
# fuel consumption during timestep unequal to one hour
# it is assumed that each simpy timestep equals one hour
t = env.now
fuel = simpy_car.power * (t - t_prev) * 3600 / (E_OIL * EFFICIENCY)
t_prev = t
yield env.process(simpy_car.consume(env, timestep, fuel, lat))
except sp.Interrupt as e:
action = e.cause
while True:
try:
if action == 'weather':
yield env.process(simpy_car.refuel(env, simpy_tankcar))
elif action == 'tanking':
yield env.process(simpy_car.tanking(env, simpy_tankcar))
simpy_car.status = 'DRIVING'
elif action == 'refuelling':
simpy_tankcar.status = 'DRIVING'
simpy_car.status = 'DRIVING'
action = None
break
except sp.Interrupt as e:
action = e.cause

try:
yield env.process(simpy_car.check_fuel(env, simpy_tankcar))
except sp.Interrupt as e:
action = e.cause
while True:
try:
if action == 'weather':
yield env.process(simpy_car.refuel(env, simpy_tankcar))
elif action == 'tanking':
yield env.process(simpy_car.tanking(env, simpy_tankcar))
simpy_car.status = 'DRIVING'
elif action == 'refuelling':
simpy_tankcar.status = 'DRIVING'
simpy_car.status = 'DRIVING'
action = None
break
except sp.Interrupt as e:
action = e.cause

yield from ()


Below the code with the function and function calls

def process_interrupt(action, simpy_car, simpy_tankcar):
"""
State machine
"""
while True:
try:
if action == 'weather':
yield env.process(simpy_car.refuel(env, simpy_tankcar))
elif action == 'tanking':
yield env.process(simpy_car.tanking(env, simpy_tankcar))
simpy_car.status = 'DRIVING'
elif action == 'refuelling':
simpy_tankcar.status = 'DRIVING'
simpy_car.status = 'DRIVING'
action = None
break
except sp.Interrupt as e:
action = e.cause
return action



def offer(env, simpy_car, simpy_tankcar, route, timestep):
action = None
t_prev = -1
for lat in route:
try:
t = env.now
fuel = simpy_car.power * (t - t_prev) * 3600 / (E_OIL * EFFICIENCY)
t_prev = t
yield env.process(simpy_car.consume(env, timestep, fuel, lat))
except sp.Interrupt as e:
action = e.cause
action = process_interrupt(action, simpy_car, simpy_tankcar)

try:
yield env.process(simpy_car.check_fuel(env, simpy_tankcar))
except sp.Interrupt as e:
action = e.cause
action = process_interrupt(action, simpy_car, simpy_tankcar)

yield from ()


I expect both versions to yield the same results, but they don't. What am I doing wrong? Why does the function version yield different results?

Continue reading...