Utility classes and functions#

Msg#

Namedtuple sub-class to encapsulate a message from the plan to the RE.

To maintain a peristent set of meta-data between Python sessions we include a dictionary duck-type based on zict.Func.

`PersistentDict`	A MutableMapping which syncs it contents to disk.
`PersistentDict.directory`

We define a number of Exception sub-classes for internal signaling.

`RunEngineControlException`	Exception for signaling within the RunEngine.
`RequestAbort`	Request that the current run be aborted.
`RequestStop`	Request that the current run be stopped and marked successful.
`RunEngineInterrupted`
`NoReplayAllowed`
`IllegalMessageSequence`
`FailedPause`
`FailedStatus`	Exception to be raised if a SatusBase object reports done but failed
`InvalidCommand`
`PlanHalt`
`RampFail`

These are used by the RunEngine to display progress bars and are the clients of the watch API

`ProgressBar.update`	This method is registered with Status.watch() to receive updates.
`ProgressBar.draw`	Clear the display
`ProgressBar.clear`

These objects encapsulate what the RunEngine should do on its thread while waiting for the plan to complete in the background thread

`DuringTask`	This class waits on the event (which fully blocks the thread).
`DuringTask.block`	Wait plan to finish.
`DefaultDuringTask`	This class run the Qt main loop while waiting for the plan to finish.