Edit: preloaded.py
# util/preloaded.py # Copyright (C) 2005-2025 the SQLAlchemy authors and contributors # <see AUTHORS file> # # This module is part of SQLAlchemy and is released under # the MIT License: https://www.opensource.org/licenses/mit-license.php # mypy: allow-untyped-defs, allow-untyped-calls """supplies the "preloaded" registry to resolve circular module imports at runtime. """ from __future__ import annotations import sys from typing import Any from typing import Callable from typing import TYPE_CHECKING from typing import TypeVar _FN = TypeVar("_FN", bound=Callable[..., Any]) if TYPE_CHECKING: from sqlalchemy import dialects as _dialects from sqlalchemy import orm as _orm from sqlalchemy.engine import cursor as _engine_cursor from sqlalchemy.engine import default as _engine_default from sqlalchemy.engine import reflection as _engine_reflection from sqlalchemy.engine import result as _engine_result from sqlalchemy.engine import url as _engine_url from sqlalchemy.orm import attributes as _orm_attributes from sqlalchemy.orm import base as _orm_base from sqlalchemy.orm import clsregistry as _orm_clsregistry from sqlalchemy.orm import decl_api as _orm_decl_api from sqlalchemy.orm import decl_base as _orm_decl_base from sqlalchemy.orm import dependency as _orm_dependency from sqlalchemy.orm import descriptor_props as _orm_descriptor_props from sqlalchemy.orm import mapperlib as _orm_mapper from sqlalchemy.orm import properties as _orm_properties from sqlalchemy.orm import relationships as _orm_relationships from sqlalchemy.orm import session as _orm_session from sqlalchemy.orm import state as _orm_state from sqlalchemy.orm import strategies as _orm_strategies from sqlalchemy.orm import strategy_options as _orm_strategy_options from sqlalchemy.orm import util as _orm_util from sqlalchemy.sql import default_comparator as _sql_default_comparator from sqlalchemy.sql import dml as _sql_dml from sqlalchemy.sql import elements as _sql_elements from sqlalchemy.sql import functions as _sql_functions from sqlalchemy.sql import naming as _sql_naming from sqlalchemy.sql import schema as _sql_schema from sqlalchemy.sql import selectable as _sql_selectable from sqlalchemy.sql import sqltypes as _sql_sqltypes from sqlalchemy.sql import traversals as _sql_traversals from sqlalchemy.sql import util as _sql_util # sigh, appease mypy 0.971 which does not accept imports as instance # variables of a module dialects = _dialects engine_cursor = _engine_cursor engine_default = _engine_default engine_reflection = _engine_reflection engine_result = _engine_result engine_url = _engine_url orm_clsregistry = _orm_clsregistry orm_base = _orm_base orm = _orm orm_attributes = _orm_attributes orm_decl_api = _orm_decl_api orm_decl_base = _orm_decl_base orm_descriptor_props = _orm_descriptor_props orm_dependency = _orm_dependency orm_mapper = _orm_mapper orm_properties = _orm_properties orm_relationships = _orm_relationships orm_session = _orm_session orm_strategies = _orm_strategies orm_strategy_options = _orm_strategy_options orm_state = _orm_state orm_util = _orm_util sql_default_comparator = _sql_default_comparator sql_dml = _sql_dml sql_elements = _sql_elements sql_functions = _sql_functions sql_naming = _sql_naming sql_selectable = _sql_selectable sql_traversals = _sql_traversals sql_schema = _sql_schema sql_sqltypes = _sql_sqltypes sql_util = _sql_util class _ModuleRegistry: """Registry of modules to load in a package init file. To avoid potential thread safety issues for imports that are deferred in a function, like https://bugs.python.org/issue38884, these modules are added to the system module cache by importing them after the packages has finished initialization. A global instance is provided under the name :attr:`.preloaded`. Use the function :func:`.preload_module` to register modules to load and :meth:`.import_prefix` to load all the modules that start with the given path. While the modules are loaded in the global module cache, it's advisable to access them using :attr:`.preloaded` to ensure that it was actually registered. Each registered module is added to the instance ``__dict__`` in the form `<package>_<module>`, omitting ``sqlalchemy`` from the package name. Example: ``sqlalchemy.sql.util`` becomes ``preloaded.sql_util``. """ def __init__(self, prefix="sqlalchemy."): self.module_registry = set() self.prefix = prefix def preload_module(self, *deps: str) -> Callable[[_FN], _FN]: """Adds the specified modules to the list to load. This method can be used both as a normal function and as a decorator. No change is performed to the decorated object. """ self.module_registry.update(deps) return lambda fn: fn def import_prefix(self, path: str) -> None: """Resolve all the modules in the registry that start with the specified path. """ for module in self.module_registry: if self.prefix: key = module.split(self.prefix)[-1].replace(".", "_") else: key = module if ( not path or module.startswith(path) ) and key not in self.__dict__: __import__(module, globals(), locals()) self.__dict__[key] = globals()[key] = sys.modules[module] _reg = _ModuleRegistry() preload_module = _reg.preload_module import_prefix = _reg.import_prefix # this appears to do absolutely nothing for any version of mypy # if TYPE_CHECKING: # def __getattr__(key: str) -> ModuleType: # ...
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