Pause in a loop

[manuel]

I've two modules: main.py and eval.py

Eval.py is imported in main.py, but I've a loop
in eval.py that must call a function in main.py...

I can't import main.py in eval.py too, because
that would create an import loop.

But I'm thinking a different solution:
a pause in a loop to return periodically an
output. It's possible?


thanks,

Manuel

[Michael Peuser]

Re: Pause in a loop

"manuel" <manuelbastioni NOSPAM@tin.it> schrieb im Newsbeitrag
news:%W7Ta.1036 0$t92.299097@ne ws1.tin.it...[color=blue]
>
> I've two modules: main.py and eval.py
>
> Eval.py is imported in main.py, but I've a loop
> in eval.py that must call a function in main.py...[/color]
......

How is that loop activated in the first place? If you activate it by a call
just provide your main-proc as a callback parameter in that call...

Kindly
Michael

[Jp Calderone]

Re: Pause in a loop

On Tue, Jul 22, 2003 at 10:00:27AM +0000, manuel wrote:[color=blue]
>
> I've two modules: main.py and eval.py
>
> Eval.py is imported in main.py, but I've a loop
> in eval.py that must call a function in main.py...
>
> I can't import main.py in eval.py too, because
> that would create an import loop.
>
> But I'm thinking a different solution:
> a pause in a loop to return periodically an
> output. It's possible?
>[/color]

Generators, or "resumable functions" may be one possible solution for
this:

from __future__ import generators # Necessary until Python 2.3

class MoreWorkToDo:
pass

class NearlyDone:
pass

def f1():
for i in xrange(100):
do_something_ex pensive_and_slo w()
yield MoreWorkToDo
for i in xrange(10):
cleanup_a_littl e()
yield NearlyDone

def f2():
for x in f1():
print str(x),

Another possibility is to use a callback:

class MoreWorkToDo:
pass

class NearlyDone:
pass

def f1(perLoop):
for i in xrange(100):
do_something_ex pensive_and_slo w()
perLoop(MoreWor kToDo)
for i in xrange(10):
cleanup_a_littl e()
perLoop(NearlyD one)

def cbFunc(v):
print str(v),

def f2():
f1(cbFunc)

Still another approach might create an iterator out of an explicit state
machine:

class MoreWorkToDo:
pass

class NearlyDone:
pass

class Worker:
def __iter__(self):
return _WorkerIter()

class _WorkerIter:
def __init__(self):
self.state = 'working'
self.workCount = 100
self.cleanCount = 10

def next(self):
return getattr(self, 'state_' + self.state)()

def state_working(s elf):
do_something_ex pensive_and_slo w()
self.workCount -= 1
if self.workCount <= 0:
self.state = 'cleanup'
return MoreWorkToDo

def state_cleanup(s elf):
cleanup_a_littl e()
self.cleanCount -= 1
if self.cleanCount <= 0:
raise StopIteration()
return NearlyDone

def f2():
for x in Worker():
print str(x),

The iterator solution is very similar to the generator solution (in fact,
the generator also creates an iterator, just a different kind) but as you
can see is a bit more code. The advantage is the iterator version may be
able to continue if an unexpected exception is raised in one of the calls to
`next', whereas the generator form will never be able to do so. The
iterator version is also pickleable.

Hope this helps,

Jp[color=blue]
>
> thanks,
>
> Manuel
>
>
> --
> http://mail.python.org/mailman/listinfo/python-list[/color]

--
"If you find a neighbor in need, you're responsible for serving that
neighbor in need, you're responsible for loving a neighbor just like you'd
like to love yourself." -- George W. Bush, Sept. 16, 2002

[Gilles Lenfant]

Re: Pause in a loop

"manuel" <manuelbastioni NOSPAM@tin.it> a écrit dans le message de news:
%W7Ta.10360$t92 .299097@news1.t in.it...[color=blue]
>
> I've two modules: main.py and eval.py
>
> Eval.py is imported in main.py, but I've a loop
> in eval.py that must call a function in main.py...
>
> I can't import main.py in eval.py too, because
> that would create an import loop.
>
> But I'm thinking a different solution:
> a pause in a loop to return periodically an
> output. It's possible?
>
>
> thanks,
>
> Manuel
>
>[/color]

Send that function to the eval as parameter...

<main.py>
....
import eval

def myfunc(...)
...
def main():
...
eval.eval(x, y, z, myfunc)
....
</main.py>

<eval.py>
....
def eval(x, y, z, afunc):
...
afunc(...)
....
return stuff
....
</eval.py>

[manuel]

Re: Pause in a loop

Thanks, now I try the various soluctions,
and after tell here the result.

THANKS,

Manuel

The same question is here, but Blender oriented:

http://www.elysiun.com/forum/viewtopic.php?t=11701&highlight=