Python: generator expression vs. yield

Question

In Python, is there any difference between creating a generator object through a generator expression versus using the yield statement?

Answer 1

In this example, not really. But yield can be used for more complex constructs - for example it can accept values from the caller as well and modify the flow as a result. Read PEP 342 for more details (it's an interesting technique worth knowing).

Anyway, the best advice is use whatever is clearer for your needs.

P.S. Here's a simple coroutine example from Dave Beazley:

def grep(pattern):
    print "Looking for %s" % pattern
    while True:
        line = (yield)
        if pattern in line:
            print line,

# Example use
if __name__ == '__main__':
    g = grep("python")
    g.next()
    g.send("Yeah, but no, but yeah, but no")
    g.send("A series of tubes")
    g.send("python generators rock!")