TaskParameter quirks

task_params.py

import luigi


class Foo(luigi.Task):
    message = 'Foo'


class RunOnceTask(luigi.Task):
    my_task = luigi.TaskParameter()

    _comp = False

    def complete(self):
        return RunOnceTask._comp

    def run(self):
        print('\n==> TASK:{}, TYPE:{}\n'.format(
            self.my_task, type(self.my_task)))
        RunOnceTask._comp = True


# Task param passed as class name
class A1(luigi.Task):
    """Works as expected."""

    def requires(self):
        yield RunOnceTask(my_task=Foo)


class A2(luigi.Task):
    """But then this fails... luigi.task_register.TaskClassNotFoundException"""

    def run(self):
        yield RunOnceTask(my_task=Foo)


# Task class passed as string
class B1(luigi.Task):
    """Task runs, but task parameter is parsed as a string, not task."""

    def requires(self):
        yield RunOnceTask(my_task='Foo')


class B2(luigi.Task):
    """Works.  Task string converted to task class."""

    def run(self):
        yield RunOnceTask(my_task='Foo')


if __name__ == '__main__':
    luigi.run()