Simplified module pre-loading strategy and made it linter friendly

Introduced a modules registry to register modules that should be lazily loaded
in the package init. This ensures that they are in the system module cache,
avoiding potential thread safety issues as when importing them directly
in the function that uses them. The module registry is used to obtain
these modules directly, ensuring that the all the lazily loaded modules
are resolved at the proper time

This replaces dependency_for decorator and the dependencies decorator logic,
removing the need to pass the resolved modules as arguments of the
decodated functions and removes possible errors caused by linters.

Fixes: #4689
Fixes: #4656
Change-Id: I2e291eba4297867fc0ddb5d875b9f7af34751d01

1 files changed, 8 insertions, 7 deletions

diff --git a/lib/sqlalchemy/sql/base.py b/lib/sqlalchemy/sql/base.py
index 89839ea28..b61c7dc5e 100644
--- a/lib/sqlalchemy/sql/base.py
+++ b/lib/sqlalchemy/sql/base.py
@@ -209,6 +209,14 @@ class _DialectArgDict(util.collections_abc.MutableMapping):
         del self._non_defaults[key]
 
 
+@util.preload_module("sqlalchemy.dialects")
+def _kw_reg_for_dialect(dialect_name):
+    dialect_cls = util.preloaded.dialects.registry.load(dialect_name)
+    if dialect_cls.construct_arguments is None:
+        return None
+    return dict(dialect_cls.construct_arguments)
+
+
 class DialectKWArgs(object):
     """Establish the ability for a class to have dialect-specific arguments
     with defaults and constructor validation.
@@ -307,13 +315,6 @@ class DialectKWArgs(object):
         """A synonym for :attr:`.DialectKWArgs.dialect_kwargs`."""
         return self.dialect_kwargs
 
-    @util.dependencies("sqlalchemy.dialects")
-    def _kw_reg_for_dialect(dialects, dialect_name):
-        dialect_cls = dialects.registry.load(dialect_name)
-        if dialect_cls.construct_arguments is None:
-            return None
-        return dict(dialect_cls.construct_arguments)
-
     _kw_registry = util.PopulateDict(_kw_reg_for_dialect)
 
     def _kw_reg_for_dialect_cls(self, dialect_name):