You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
69 lines
2.3 KiB
69 lines
2.3 KiB
3 years ago
|
# 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.
|
||
|
|
|
||
|
|
"""
|
||
|
|
|
||
|
|
import sys
|
||
|
|
|
||
|
|
from . import compat
|
||
|
|
|
||
|
|
|
||
|
|
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):
|
||
|
|
"""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):
|
||
|
|
"""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__:
|
||
|
|
compat.import_(module, globals(), locals())
|
||
|
|
self.__dict__[key] = sys.modules[module]
|
||
|
|
|
||
|
|
|
||
|
|
preloaded = _ModuleRegistry()
|
||
|
|
preload_module = preloaded.preload_module
|