Units signal metadata

[abbiemery]

Fixes #146 . Rebase of #137 .

Propagates units and precision metadata (if present) from PVA or CA signal backends.

[abbiemery]

Are we waiting on PVA changes for this, or that a different PR?

[coretl]

Could this be written more simply?

Suggested change

	def _limits_from_value(value: Value) -> Limits:
	valueAlarm = getattr(value, "valueAlarm", None)
	_empty_limit = LimitPair(low=None, high=None)
	def get_control_or_display_limit(limit: str) -> LimitPair:
	if (control_or_display := getattr(value, limit, None)) is None:
	return _empty_limit
	low = getattr(control_or_display, "limitLow", None)
	high = getattr(control_or_display, "limitHigh", None)
	return LimitPair(
	low=None if isnan(low) else low, high=None if isnan(high) else high
	)
	def get_alarm_or_warning_limit(limit: str) -> LimitPair:
	if valueAlarm is None:
	return _empty_limit
	low = getattr(valueAlarm, f"low{limit}Limit", None)
	high = getattr(valueAlarm, f"high{limit}Limit", None)
	return LimitPair(
	low=None if isnan(low) else low, high=None if isnan(high) else high
	)
	return Limits(
	alarm=get_alarm_or_warning_limit("Alarm"),
	control=get_control_or_display_limit("control"),
	display=get_control_or_display_limit("display"),
	warning=get_alarm_or_warning_limit("Warning"),
	)
	def _limits_from_value(value: Value) -> Limits:
	def get_limits(substucture_name: str, infix: str = "") -> LimitPair:
	substructure = getattr(value, substucture_name, None)
	low = getattr(substructure, f"low{infix}Limit", None)
	high = getattr(substructure, f"high{infix}Limit", None)
	return LimitPair(
	low=None if isnan(low) else low, high=None if isnan(high) else high
	)
	return Limits(
	alarm=get_limits("valueAlarm", infix="Alarm"),
	control=get_limits("control"),
	display=get_limits("display"),
	warning=get_limits("valueAlarm", infix="Warning"),
	)

[abbiemery]

Unfortunately the suggestion fails quite a number of tests but i'll have a look.

[DiamondJoseph]

Not quite, it's low{infix}Limit but limitLow for the others.

[abbiemery]

So I am inclined to leave it as it is.

[coretl]

How about?

Suggested change

	def _limits_from_value(value: Value) -> Limits:
	valueAlarm = getattr(value, "valueAlarm", None)
	_empty_limit = LimitPair(low=None, high=None)
	def get_control_or_display_limit(limit: str) -> LimitPair:
	if (control_or_display := getattr(value, limit, None)) is None:
	return _empty_limit
	low = getattr(control_or_display, "limitLow", None)
	high = getattr(control_or_display, "limitHigh", None)
	return LimitPair(
	low=None if isnan(low) else low, high=None if isnan(high) else high
	)
	def get_alarm_or_warning_limit(limit: str) -> LimitPair:
	if valueAlarm is None:
	return _empty_limit
	low = getattr(valueAlarm, f"low{limit}Limit", None)
	high = getattr(valueAlarm, f"high{limit}Limit", None)
	return LimitPair(
	low=None if isnan(low) else low, high=None if isnan(high) else high
	)
	return Limits(
	alarm=get_alarm_or_warning_limit("Alarm"),
	control=get_control_or_display_limit("control"),
	display=get_control_or_display_limit("display"),
	warning=get_alarm_or_warning_limit("Warning"),
	)
	def _limits_from_value(value: Value) -> Limits:
	def get_limits(substucture_name: str, low_name: str = "limitLow", high_name: str = "limitHigh") -> LimitPair:
	substructure = getattr(value, substucture_name, None)
	low = getattr(substructure, low_name, None)
	high = getattr(substructure, high_name, None)
	return LimitPair(
	low=None if isnan(low) else low, high=None if isnan(high) else high
	)
	return Limits(
	alarm=get_limits("valueAlarm", "lowAlarmLimit", "highAlarmLimit"),
	control=get_limits("control"),
	display=get_limits("display"),
	warning=get_limits("valueAlarm", "lowWarningLimit", "highWarningLimit"),
	)

[abbiemery]

Still no. Is this worth blocking on? Can I make an issue to put in the upcoming sprint to refactor it, it would be a good first issue.

[DiamondJoseph]

Got there in the end (assuming this passes), made a minor change to getattr(foo, bar, nan) as isnan(None) becomes unhappy. I'm assuming that if the attr is there (substructure is not None and hasattr(substructure, attr)) it will never be None