Demonstrate cycle reference creation when final enumeration over a generator yields a bound method.

cycle_reference_enumeration.py

"""
When line
    yield {"hook": normal_hook}
is commented:
> In hook()
> After run_macro
> In Macro.__del__()
> In CTScan.__del__()

When line
    yield {"hook": normal_hook}
is NOT commented:
> In hook()
> In normal_hook()
> In Macro.__del__()
> In CTScan.__del__()
> After run_macro
"""
from taurus.core.util.event import CallableRef


def normal_hook():
    print("In normal_hook()")


class CTScan:
    
    def __init__(self, generator):
        self._generator = CallableRef(generator)

    def __del__(self):
        print("In CTScan.__del__()")
    

    @property
    def generator(self):
        """Generator of steps or waypoints used in this scan."""
        return self._generator()
    
    @property
    def steps(self):
        if not hasattr(self, "_steps"):
            self._steps = enumerate(self.generator())
        return self._steps

    def scan(self):
        for i, waypoint in enumerate(self.generator()):
            waypoint["hook"]()


class Macro:

    def __del__(self):
        print("In Macro.__del__()")

    def hook(self):
        print("In hook()")
    
    def generator(self):
        yield {"hook": self.hook}
        # yield {"hook": normal_hook}
    
    def run(self):
        self.gscan = CTScan(self.generator)
        self.gscan.scan()


def run_macro():
    macro = Macro()
    macro.run()

if __name__ == "__main__":
    run_macro()
    print("After run_macro")