diff options
Diffstat (limited to 'lib/sqlalchemy/sql/roles.py')
-rw-r--r-- | lib/sqlalchemy/sql/roles.py | 29 |
1 files changed, 29 insertions, 0 deletions
diff --git a/lib/sqlalchemy/sql/roles.py b/lib/sqlalchemy/sql/roles.py index 787a1c25e..b41ef7a5d 100644 --- a/lib/sqlalchemy/sql/roles.py +++ b/lib/sqlalchemy/sql/roles.py @@ -4,10 +4,17 @@ # # This module is part of SQLAlchemy and is released under # the MIT License: https://www.opensource.org/licenses/mit-license.php +import typing +from sqlalchemy.util.langhelpers import TypingOnly from .. import util +if typing.TYPE_CHECKING: + from .elements import ClauseElement + from .selectable import FromClause + + class SQLRole: """Define a "role" within a SQL statement structure. @@ -284,3 +291,25 @@ class DDLReferredColumnRole(DDLConstraintColumnRole): _role_name = ( "String column name or Column object for DDL foreign key constraint" ) + + +class HasClauseElement(TypingOnly): + """indicates a class that has a __clause_element__() method""" + + __slots__ = () + + if typing.TYPE_CHECKING: + + def __clause_element__(self) -> "ClauseElement": + ... + + +class HasFromClauseElement(HasClauseElement, TypingOnly): + """indicates a class that has a __clause_element__() method""" + + __slots__ = () + + if typing.TYPE_CHECKING: + + def __clause_element__(self) -> "FromClause": + ... |