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|
# util/_preloaded.py
# Copyright (C) 2005-2022 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
"""supplies the "preloaded" registry to resolve circular module imports at
runtime.
"""
from __future__ import annotations
import sys
from types import ModuleType
import typing
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.engine import default as engine_default
from sqlalchemy.orm import session as orm_session
from sqlalchemy.orm import util as orm_util
from sqlalchemy.sql import dml as sql_dml
from sqlalchemy.sql import functions as sql_functions
from sqlalchemy.sql import util as 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]
if typing.TYPE_CHECKING:
def __getattr__(self, key: str) -> ModuleType:
...
_reg = _ModuleRegistry()
preload_module = _reg.preload_module
import_prefix = _reg.import_prefix
if TYPE_CHECKING:
def __getattr__(key: str) -> ModuleType:
...
|
