From 41e18d2c893f56c8fe9b718477a56dd755079635 Mon Sep 17 00:00:00 2001
From: Roman Mogylatov <rmogilatov@gmail.com>
Date: Thu, 28 Jan 2021 19:18:47 -0500
Subject: [PATCH] Implement wiring autoloader

---
 src/dependency_injector/wiring.py     | 101 ++++++++++++++++++++++++++
 tests/unit/wiring/test_wiring_py36.py |  36 ++++++++-
 2 files changed, 136 insertions(+), 1 deletion(-)

diff --git a/src/dependency_injector/wiring.py b/src/dependency_injector/wiring.py
index c738bf02..81fa3985 100644
--- a/src/dependency_injector/wiring.py
+++ b/src/dependency_injector/wiring.py
@@ -4,6 +4,7 @@ import asyncio
 import functools
 import inspect
 import importlib
+import importlib.machinery
 import pkgutil
 import sys
 from types import ModuleType
@@ -52,6 +53,11 @@ __all__ = (
     'Provide',
     'Provider',
     'Closing',
+    'register_loader_containers',
+    'unregister_loader_containers',
+    'install_loader',
+    'uninstall_loader',
+    'is_loader_installed',
 )
 
 T = TypeVar('T')
@@ -535,3 +541,98 @@ class Provider(_Marker):
 
 class Closing(_Marker):
     ...
+
+
+class AutoLoader:
+    """Auto-wiring module loader.
+
+    Automatically wire containers when modules are imported.
+    """
+
+    def __init__(self):
+        self.containers = []
+        self._path_hook = None
+
+    def register_containers(self, *containers):
+        self.containers.extend(containers)
+
+        if not self.installed:
+            self.install()
+
+    def unregister_containers(self, *containers):
+        for container in containers:
+            self.containers.remove(container)
+
+        if not self.containers:
+            self.uninstall()
+
+    def wire_module(self, module):
+        for container in self.containers:
+            container.wire(modules=[module])
+
+    @property
+    def installed(self):
+        return self._path_hook is not None
+
+    def install(self):
+        if self.installed:
+            return
+
+        loader = self
+
+        class SourcelessFileLoader(importlib.machinery.SourcelessFileLoader):
+            def exec_module(self, module):
+                super().exec_module(module)
+                loader.wire_module(module)
+
+        class SourceFileLoader(importlib.machinery.SourceFileLoader):
+            def exec_module(self, module):
+                super().exec_module(module)
+                loader.wire_module(module)
+
+        loader_details = [
+            (SourcelessFileLoader, importlib.machinery.BYTECODE_SUFFIXES),
+            (SourceFileLoader, importlib.machinery.SOURCE_SUFFIXES),
+        ]
+
+        self._path_hook = importlib.machinery.FileFinder.path_hook(*loader_details)
+
+        sys.path_hooks.insert(0, self._path_hook)
+        sys.path_importer_cache.clear()
+        importlib.invalidate_caches()
+
+    def uninstall(self):
+        if not self.installed:
+            return
+
+        sys.path_hooks.remove(self._path_hook)
+        sys.path_importer_cache.clear()
+        importlib.invalidate_caches()
+
+
+_loader = AutoLoader()
+
+
+def register_loader_containers(*containers: Container) -> None:
+    """Register containers in auto-wiring module loader."""
+    _loader.register_containers(*containers)
+
+
+def unregister_loader_containers(*containers: Container) -> None:
+    """Unregister containers from auto-wiring module loader."""
+    _loader.unregister_containers(*containers)
+
+
+def install_loader() -> None:
+    """Install auto-wiring module loader hook."""
+    _loader.install()
+
+
+def uninstall_loader() -> None:
+    """Uninstall auto-wiring module loader hook."""
+    _loader.uninstall()
+
+
+def is_loader_installed() -> bool:
+    """Check if auto-wiring module loader hook is installed."""
+    return _loader.installed
diff --git a/tests/unit/wiring/test_wiring_py36.py b/tests/unit/wiring/test_wiring_py36.py
index 84938a6a..25f4b9f2 100644
--- a/tests/unit/wiring/test_wiring_py36.py
+++ b/tests/unit/wiring/test_wiring_py36.py
@@ -1,7 +1,15 @@
+import contextlib
 from decimal import Decimal
+import importlib
 import unittest
 
-from dependency_injector.wiring import wire, Provide, Closing
+from dependency_injector.wiring import (
+    wire,
+    Provide,
+    Closing,
+    register_loader_containers,
+    unregister_loader_containers,
+)
 from dependency_injector import errors
 
 # Runtime import to avoid syntax errors in samples on Python < 3.5
@@ -367,3 +375,29 @@ class WiringAsyncInjectionsTest(AsyncTestCase):
         self.assertIs(resource2, asyncinjections.resource2)
         self.assertEqual(asyncinjections.resource2.init_counter, 2)
         self.assertEqual(asyncinjections.resource2.shutdown_counter, 2)
+
+
+class AutoLoaderTest(unittest.TestCase):
+
+    container: Container
+
+    def setUp(self) -> None:
+        self.container = Container(config={'a': {'b': {'c': 10}}})
+        importlib.reload(module)
+
+    def tearDown(self) -> None:
+        with contextlib.suppress(ValueError):
+            unregister_loader_containers(self.container)
+
+        self.container.unwire()
+
+    @classmethod
+    def tearDownClass(cls) -> None:
+        importlib.reload(module)
+
+    def test_register_container(self):
+        register_loader_containers(self.container)
+        importlib.reload(module)
+
+        service = module.test_function()
+        self.assertIsInstance(service, Service)