Carl Cerecke wrote:
> Fredrik Lundh wrote:
>
>> Carl Cerecke wrote:
>>
>>
>>> It turns out that generators are more efficient than the eval function
>>> excuting bits of compiled code. About 20-25% faster.
>>
>>
>>
>> why are you using generators to return things from a function, when
>> you can just return the things ?
>
>
> Trying to find the fastest way to implement finite state machine.
> The included file times 4 different ways, with functions the fastest.
>
> The reason, I think, for the unusual sequence if id()s of the generators
> - see grandparent post - (and the reason for their poor performance
> compared to functions), is because the reference to the generator is
> being lost, then another generator is being created with the same id.
> Properly done, I would expect generators to out perform functions.
Generator FSM done properly (well, better anyway). They are still almost
twice as slow as plain function calls, though.
def g_on():
while 1:
action = next_action()
if action == 'lift':
yield s_g_on
elif action == 'push':
yield s_g_off
else:
break
yield None
def g_off():
while 1:
action = next_action()
if action == 'lift':
yield s_g_on
elif action == 'push':
yield s_g_off
else:
break
yield None
def actions(n):
import random
for i in range(n-1):
yield random.choice(['lift','push'])
yield None
r = 1000000
#r = 10
next_action = actions(r).next
s_g_on = g_on()
s_g_off = g_off()
state = s_g_on
while state:
state = state.next()
z = time.clock()
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