JezK
Edit File: _preloaded.py
# util/_preloaded.py # Copyright (C) 2005-2023 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