eykd / owyl Goto Github PK

Running an Owyl tree and something else concurrently in the same application is only possible with threading right now.

There is a safer and more modern alternative - asyncio, which is in the standard library. Lots of libraries are already compatible with it. This can also be a good time to upgrade Owyl to Python3.

It helps a lot that Asyncio's code patterns are very similar to Owyl's:

@owyl.parent_task
def sequence(*children, **kwargs):
    final_value = True
    for child in children:
        result = yield child(**kwargs)
        if not result and result is not None:
            final_value = False
            break
    yield final_value

@asyncio.coroutine
def sequence(*children, **kwargs):
    for coroutine in children:
        result = yield from coroutine(**kwargs)
        if not result:
            return False
    return True

The #2 PR appears to have dredged up a bunch of problems. In mucking around with parallel I've realized that sequence and selector leak child return values:

        tree = owyl.sequence(owyl.succeed(),
                             owyl.succeed(),
                             owyl.fail(),
                             owyl.succeed())
        v = owyl.visit(tree)

        results = [x for x in v if x is not None]
        self.assertEqual(results, [True, True, False, False])

See how the succeed()/succeed()/fail() leaks out to the results? The first three results are from the sequence children, while the 4th result is the sequence itself failing.

It's been a few years since I designed this library, but I can't think for the life of me why they would do that. Do any of you using owyl depend on this behavior?

This is not an issue, but an FYI.

https://github.com/hansonrobotics/owylviz/tree/master