monarchs.config.Rule

class monarchs.config.Rule

A cross-setting consistency check.

For example, we don’t want to let a user specify both a DEM path and a firn column height - these two settings conflict, and we don’t want the model to silently make choices about which of those to use.

failed_when is a callable that returns True when the rule is violated. It is written as a lambda so the check lives with the rule, and because it is a function it is only evaluated when the rules are run (in apply.check_rules), not when the catalogue is imported. This lets a rule refer to other settings without worrying about the order in which they are loaded (e.g. a rule can set a value based on another value).

To add a rule, append one to rules.RULES:

Rule(
    failed_when=lambda ms: ms.dump_data and not hasattr(ms, "dump_filepath"),
    message="dump_data needs a dump_filepath to write to.",
    error=NameError,   # omit for a plain ValueError
)

failed_when is a lambda function - equivalent to doing def failed_when_func(ms):

return ms.dump_data and not hasattr(ms, “dump_filepath”)

Use getattr(ms, "x", default) / hasattr for settings that may not be present yet (rules run before defaults are filled).

error: type

failed_when: Callable

message: str