path: root/abdl/feature.py

# This file is part of A Boneless Datastructure Language
# Copyright (C) 2020  Soni L.
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero 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 Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <https://www.gnu.org/licenses/>.

"""Feature Deprecation Control.

When features get deprecated, they show up here.

Libraries must never use this module directly. Instead, it should be up to
applications and test suites to use this module.
"""

class PredicateTypePredicate(DeprecationWarning):
    """Indicates that a Predicate type is being used as a predicate.

    This usually indicates a bug.

    The following triggers this warning:

        >>> import abdl
        >>> abdl.match("->x:$x", "x", {"x": abdl.predicates.Predicate})

    The following doesn't:

        >>> import abdl
        >>> predicate = abdl.predicates.IsInstance(abdl.predicates.Predicate)
        >>> abdl.match("->x:$x", "x", {"x": predicate})
    """