Generator Frustration

[Thomas Rachel]

Am 04.06.2011 20:27 schrieb TommyVee:
> I'm using the SimPy package to run simulations. Anyone who's used this
> package knows that the way it simulates process concurrency is through
> the clever use of yield statements. Some of the code in my programs is
> very complex and contains several repeating sequences of yield
> statements. I want to combine these sequences into common functions.

Which are then generators.

 > The problem of course, is that once a yield gets put into a function,
 > the function is now a generator and its behavior changes.

Isn't your "main" function a generator as well?


> Is there  any elegant way to do this? I suppose I can do things like
 > ping-pong yield statements, but that solutions seems even uglier than
 > having a very flat, single main routine with repeating sequences.

I'm not sure if I got it right, but I think you could emulate this 
"yield from" with a decorator:

def subgen1(): yield 1; yield 2;
def subgen2(): yield 1; yield 2;

Instead of doing now

def allgen():
     for i in subgen1(): yield i
     for i in subgen2(): yield i

you as well could do:

def yield_from(f):
     def wrapper(*a, **k):
         for sub in f(*a, **k):
             for i in sub:
                 yield i
     return wrapper

@yield_from
def allgen():
     yield subgen1()
     yield subgen2()

(Untested.)


Thomas