Coverage for python/lsst/daf/relation/_columns/_tag.py: 82%
11 statements
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« prev ^ index » next coverage.py v6.5.0, created at 2023-01-10 02:26 -0800
1# This file is part of daf_relation.
2#
3# Developed for the LSST Data Management System.
4# This product includes software developed by the LSST Project
5# (http://www.lsst.org).
6# See the COPYRIGHT file at the top-level directory of this distribution
7# for details of code ownership.
8#
9# This program is free software: you can redistribute it and/or modify
10# it under the terms of the GNU General Public License as published by
11# the Free Software Foundation, either version 3 of the License, or
12# (at your option) any later version.
13#
14# This program is distributed in the hope that it will be useful,
15# but WITHOUT ANY WARRANTY; without even the implied warranty of
16# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17# GNU General Public License for more details.
18#
19# You should have received a copy of the GNU General Public License
20# along with this program. If not, see <http://www.gnu.org/licenses/>.
22from __future__ import annotations
24__all__ = ("ColumnTag",)
26from collections.abc import Hashable
27from typing import Protocol
30class ColumnTag(Hashable, Protocol):
31 """An interface for objects that represent columns in a relation.
33 See :ref:`lsst.daf.relation-overview-column_tags` for details.
34 """
36 @property
37 def qualified_name(self) -> str:
38 """A string that is just as unique as this `ColumnTag` is, for use in
39 engines that require a string for column names (`str`).
41 This does not need to be limited to avoid special characters; we assume
42 it can and will be appropriately quoted when necessary.
43 """
44 ...
46 @property
47 def is_key(self) -> bool:
48 """Whether this column can be used for deduplication and join
49 equality-constraints (`bool`).
51 Columns that are not keys are assumed to always be accompanied in
52 relations by related key columns that should be used instead.
53 """
54 ...