On Aug 15, 3:37 pm, "Marshall T. Vandegrift" <[EMAIL PROTECTED]>
wrote:
> Bjoern Schliessmann <[EMAIL PROTECTED]> writes:
> >> I'm trying to write a decorator which allows one to produce simple
> >> coroutines by just writing a function as a generator expression
> >> which re-receives it's arguments as a tuple from each yield.
>
> > May I ask why? Passing it the same arguments over and over is no
> > use; and there is the send method.
>
> That's what I meant. The wrapper produced by the decorator passes the
> arguments back into the generator as a tuple via the `send' method.
>
> >> The ugliness of the ArgPacker class makes me suspect that I should
> >> perhaps just manually create and track a generator when I need a
> >> function with generator-like properties.
>
> > What do you mean? I don't quite understand why you'd have to "track"
> > a generator for getting generator-like properties.
>
> Using the trivial `nextn' example from my original post with my
> decorator lets you do just:
>
> print nextn(2) # => [0, 1]
> print nextn(3) # => [2, 3, 4]
> print nextn() # => [5]
>
> Without the decorator that becomes:
>
> gen = nextn(2)
> print gen.next() # => [0, 1]
> print gen.send(3) # => [2, 3, 4]
> print gen.send(1) # => [5]
>
> The former is just that smidgen nicer, and allows you to continue to
> make use of argument defaults and varadic arguments if so desired.
>
Do you really need a generator or co-routine to do this? Maybe
you can just use a closure:
import itertools
class Foo(object):
it = itertools.count(0)
def __call__(self):
return self.y
def __init__(self, n=1):
self.y = [ Foo.it.next() for each in xrange(n) ]
def nextn(n=1):
return Foo(n)()
print nextn()
print nextn(3)
print nextn(n=2)
print nextn()
--
Hope this helps,
Steven
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