Lazy reference between tasks, include recursive references.

lazy_load_reference.py

# Lazy reference between tasks, include recursive references.

# 1. `eval` version

def ref_tasks(*tasks):
    def wrap(task1):
        def _ref_task(self):
            return eval(task1)
        return _ref_task

    def func(cls):
        for task1 in tasks:
            setattr(cls, task1, property(wrap(task1)))
        return cls
    return func


# Ref before TaskB, TaskC defined, so it's really lazy.
@ref_tasks("TaskB", "TaskC")
class TaskA(object): pass

class TaskB(object): pass
class TaskC(object): pass

# Check it.
assert TaskA().TaskB == TaskB
assert TaskA().TaskC == TaskC

# Even itself.
ref_tasks("TaskA")(TaskA)
assert TaskA().TaskA == TaskA

# 2. `import` version
"""
lib1  = importlib.import_module("tasks." + Inflector().underscore(task_name1))
task1 = getattr(lib1, task_name1)
"""