Matthew Wilson wrote:
> I'm working on two coroutines -- one iterates through a huge stream, and
> emits chunks in pieces. The other routine takes each chunk, then scores
> it as good or bad and passes that score back to the original routine, so
> it can make a copy of the stream with the score appended on.
>
> I have the code working, but it just looks really ugly. Here's a vastly
> simplified version. One function yields some numbers, and the other
> function tells me if they are even or odd.
>
> def parser():
> "I just parse and wait for feedback."
> for i in 1, 2, 3, 4, 5:
> score = (yield i)
> if score:
> print "%d passed!" % i
>
> def is_odd(n):
> "I evaluate each number n, and return True if I like it."
> if n and n % 2: return True
>
> def m():
> try:
> number_generator = parser()
> i = None
> while 1:
> i = number_generator.send(is_odd(i))
> except StopIteration: pass
>
> and here's the results when I run this:
> In [90]: m()
> 1 passed!
> 3 passed!
> 5 passed!
>
> So, clearly, the code works. But it is nonintuitive for the casual
> reader.
>
> I don't like the while 1 construct, I don't like manually
> trapping the StopIteration exception, and this line is really ugly:
>
> i = number_generator.send(is_odd(i))
>
> I really like the old for i in parser(): deal, but I can't figure out
> how to use .send(...) with that.
>
> Can anyone help me pretty this up? I want to make this as intuitive as
> possible.
Why use coroutines?
def parser(score):
for i in xrange(1, 6):
yield i
if score(i):
print "%d passed!" % i
def is_odd(n):
return n % 2
def m():
for i in parser(is_odd):
# Presumably do something here...
pass
--
Paul Hankin
--
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