Best refactoring for the dreaded While (True) loop

Question

If, like me, you shiver at the site of a While (True) loop, then you too must have thought long and hard about the best way to refactor it away. I\'ve seen several different im

Answer 1

The "running forever" situation is sometimes part of a larger state machine. Many embedded devices (with run-forever loops) don't really run forever. They often have several operating modes and will sequence among those modes.

When we built heat-pump controllers, there was a power-on-self-test (POST) mode that ran for a little while. Then there was a preliminary environmental gathering mode that ran until we figured out all the zones and thermostats and what-not.

Some engineers claimed that what came next was the "run-forever" loop. It wasn't really that simple. It was actually several operating modes that flipped and flopped. There was heating, and defrosting, and cooling, and idling, and other stuff.

My preference is to treat a "forever" loop as really just one operating mode -- there may be others at some point in the future.

someMode= True
while someMode:
    try:
        ... do stuff ...
    except SomeException, e:
        log.exception( e )
        # will keep running
    except OtherException, e:
        log.info( "stopping now" )
        someMode= False

Under some circumstances, nothing we've seen so far sets someMode to False. But I like to pretend that there'll be a mode change in some future version.