"""
A collection of descriptors used to add extra metadata
to storage class attributes.
"""
from openff.evaluator.attributes import UNDEFINED, Attribute
[docs]class FilePath(str):
"""Represents a string file path."""
pass
[docs]class StorageAttribute(Attribute):
"""A descriptor used to mark attributes of a class as those
which store information about a cached piece of data.
"""
[docs] def __init__(
self,
docstring,
type_hint,
optional=False,
):
super().__init__(docstring, type_hint, UNDEFINED, optional)
def _set_value(self, instance, value):
# Handle the special case of turning strings
# into file path objects for convenience.
if (
isinstance(value, str)
and isinstance(self.type_hint, type)
and issubclass(self.type_hint, FilePath)
):
# This is necessary as the json library currently doesn't
# support custom serialization of IntFlag or IntEnum.
value = FilePath(value)
super(StorageAttribute, self)._set_value(instance, value)
[docs]class QueryAttribute(Attribute):
"""A descriptor used to add additional metadata to
attributes of a storage query.
"""
[docs] def __init__(self, docstring, type_hint, optional=False, custom_match=False):
"""Initializes self.
Parameters
----------
custom_match: bool
Whether a custom behaviour will be implemented when
matching this attribute against the matching data object
attribute.
"""
super().__init__(docstring, type_hint, UNDEFINED, optional)
self.custom_match = custom_match