"""Dataclass utilities."""
# This file is part of FAST-OAD : A framework for rapid Overall Aircraft Design
# Copyright (C) 2022 ONERA & ISAE-SUPAERO
# FAST is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <https://www.gnu.org/licenses/>.
from dataclasses import dataclass, fields
#: To be put as default value for dataclass fields that should not have a default value.
#: See :class:`BaseDataClass` for further information.
MANDATORY_FIELD = object()
[docs]@dataclass
class BaseDataClass:
"""
This class is a workaround for the following dataclass problem:
If a dataclass defines a field with a default value, inheritor classes will not
be allowed to define fields without default value, because then the non-default fields
will follow a default field, which is forbidden.
The chosen solution (from https://stackoverflow.com/a/53085935/16488238) is to always define
default values, but mandatory fields will have the :const:`MANDATORY_FIELD` object as default.
After initialization, :meth:`__post_init__` will process fields and raise an error if
a field has :const:`MANDATORY_FIELD` as value.
"""
def __post_init__(self):
field_dict = {field.name: getattr(self, field.name) for field in fields(self)}
for name, value in field_dict.items():
if value is MANDATORY_FIELD:
raise TypeError(f"__init__ missing 1 required argument: '{name}'")