This refactors the the config error handling based on nested
context managers that add increasing amounts of information
about error locations. In other words, when we start processing
a Job object, we will:
with ParseContext.errorContext(info about job):
do some stuff
with ParseContext.errorContext(info about job attr):
do some stuff regarding the job attribute
with ParseContext.errorContext(next job attr):
do stuff with a different attr
We store a stack of error contexts on the parse context, and at any
point we can access the accumulator for the most recent one with
ParseContext.accumulator in order to add a warning or error. If we
have an attribute line number, we'll use it, otherwise we'll just
use the object-level information.
We also collapse the exception hnadlers into a single context
manager which catches exceptions and adds them to the accumulator.
This lets us decide when to catch an exception and skip to the next
phase of processing separately from where we narrow our focus to
a new object or attribute. These two actions often happen together,
but not always.
This should serve to simplify the configloader code and make it
easier to have consistent error handling within.
Change-Id: I180f9b271acd4b62039003fa8b38900f9863bad8
0ab44e153c