Add options to nest context managers in the reverse order

README.md

@@ -133,14 +133,16 @@ defined above.
 ...     @hookimpl
 ...     @contextmanager
 ...     def context(self, arg1, arg2):
-...         print('inside Plugin_1.context()')
+...         print('inside Plugin_1.context(): before')
 ...         yield arg1 + arg2
+...         print('inside Plugin_1.context(): after')
 ...
 ...     @hookimpl
 ...     @asynccontextmanager
 ...     async def acontext(self, arg1, arg2):
-...         print('inside Plugin_1.acontext()')
+...         print('inside Plugin_1.acontext(): before')
 ...         yield arg1 + arg2
+...         print('inside Plugin_1.acontext(): after')
 
 >>> class Plugin_2:
 ...     """A 2nd hook implementation namespace."""
@@ -153,14 +155,16 @@ defined above.
 ...     @hookimpl
 ...     @contextmanager
 ...     def context(self, arg1, arg2):
-...         print('inside Plugin_2.context()')
+...         print('inside Plugin_2.context(): before')
 ...         yield arg1 - arg2
+...         print('inside Plugin_2.context(): after')
 ...
 ...     @hookimpl
 ...     @asynccontextmanager
 ...     async def acontext(self, arg1, arg2):
-...         print('inside Plugin_2.acontext()')
+...         print('inside Plugin_2.acontext(): before')
 ...         yield arg1 - arg2
+...         print('inside Plugin_2.acontext(): after')
 
 ```
 
@@ -213,9 +217,24 @@ inside Plugin_1.afunc()
 ```python
 >>> with pm.with_.context(arg1=1, arg2=2) as y:  # with_ instead of hook
 ...     print(y)
-inside Plugin_2.context()
-inside Plugin_1.context()
+inside Plugin_2.context(): before
+inside Plugin_1.context(): before
 [-1, 3]
+inside Plugin_1.context(): after
+inside Plugin_2.context(): after
+
+```
+
+In the reverse order:
+
+```python
+>>> with pm.with_reverse.context(arg1=1, arg2=2) as y:  # with_reverse instead of hook
+...     print(y)
+inside Plugin_1.context(): before
+inside Plugin_2.context(): before
+[3, -1]
+inside Plugin_2.context(): after
+inside Plugin_1.context(): after
 
 ```
 
@@ -227,9 +246,27 @@ inside Plugin_1.context()
 ...         print(y)
 
 >>> asyncio.run(call_acontext())
-inside Plugin_2.acontext()
-inside Plugin_1.acontext()
+inside Plugin_2.acontext(): before
+inside Plugin_1.acontext(): before
 [-1, 3]
+inside Plugin_1.acontext(): after
+inside Plugin_2.acontext(): after
+
+```
+
+In the reverse order:
+
+```python
+>>> async def call_acontext():
+...     async with pm.awith_reverse.acontext(arg1=1, arg2=2) as y:  # awith_reverse instead of hook
+...         print(y)
+
+>>> asyncio.run(call_acontext())
+inside Plugin_1.acontext(): before
+inside Plugin_2.acontext(): before
+[3, -1]
+inside Plugin_2.acontext(): after
+inside Plugin_1.acontext(): after
 
 ```
 

src/apluggy/_wrap/awith.py

@@ -12,16 +12,26 @@ def __init__(self, pm: PluginManager_) -> None:
 
     def __getattr__(self, name: str) -> Callable[..., AsyncContextManager]:
         hook: HookCaller = getattr(self.pm.hook, name)
-        call = _Call(hook)
-        return call
+        return _Call(hook)
+
+
+class AWithReverse:
+    def __init__(self, pm: PluginManager_) -> None:
+        self.pm = pm
+
+    def __getattr__(self, name: str) -> Callable[..., AsyncContextManager]:
+        hook: HookCaller = getattr(self.pm.hook, name)
+        return _Call(hook, reverse=True)
 
 
 def _Call(
-    hook: Callable[..., list[AsyncContextManager]]
+    hook: Callable[..., list[AsyncContextManager]], reverse: bool = False
 ) -> Callable[..., AsyncContextManager]:
     @contextlib.asynccontextmanager
     async def call(*args: Any, **kwargs: Any) -> AsyncIterator[list]:
         ctxs = hook(*args, **kwargs)
+        if reverse:
+            ctxs = list(reversed(ctxs))
         async with contextlib.AsyncExitStack() as stack:
             yields = [await stack.enter_async_context(ctx) for ctx in ctxs]
 
@@ -34,20 +44,4 @@ async def call(*args: Any, **kwargs: Any) -> AsyncIterator[list]:
 
             yield yields
 
-            # TODO: The following commented out code is an attempt to support
-            # `asend()` through the `gen` attribute. It only works for
-            # simple cases. It doesn't work with starlette.lifespan().
-            # When starlette is shutting down, an exception is raised
-            # `RuntimeError: generator didn't stop after athrow()`.
-
-            # stop = False
-            # while not stop:
-            #     sent = yield yields
-            #     try:
-            #         yields = await asyncio.gather(
-            #             *[ctx.gen.asend(sent) for ctx in ctxs]
-            #         )
-            #     except StopAsyncIteration:
-            #         stop = True
-
     return call

src/apluggy/_wrap/manager.py

@@ -5,8 +5,8 @@
 from pluggy._hooks import _Plugin
 
 from .ahook import AHook
-from .awith import AWith
-from .with_ import With
+from .awith import AWith, AWithReverse
+from .with_ import With, WithReverse
 
 
 class PluginManager(PluginManager_):
@@ -116,7 +116,9 @@ def __init__(self, *args: Any, **kwargs: Any) -> None:
         super().__init__(*args, **kwargs)
         self.ahook = AHook(self)
         self.with_ = With(self)
+        self.with_reverse = WithReverse(self)
         self.awith = AWith(self)
+        self.awith_reverse = AWithReverse(self)
 
     def register(
         self, plugin: _Plugin | Callable[[], _Plugin], name: Optional[str] = None

src/apluggy/_wrap/with_.py

@@ -16,14 +16,26 @@ def __init__(self, pm: PluginManager_) -> None:
 
     def __getattr__(self, name: str) -> Callable[..., GenCtxManager]:
         hook: HookCaller = getattr(self.pm.hook, name)
-        call = _Call(hook)
-        return call
+        return _Call(hook)
 
 
-def _Call(hook: Callable[..., list[GenCtxManager]]) -> Callable[..., GenCtxManager]:
+class WithReverse:
+    def __init__(self, pm: PluginManager_) -> None:
+        self.pm = pm
+
+    def __getattr__(self, name: str) -> Callable[..., GenCtxManager]:
+        hook: HookCaller = getattr(self.pm.hook, name)
+        return _Call(hook, reverse=True)
+
+
+def _Call(
+    hook: Callable[..., list[GenCtxManager]], reverse: bool = False
+) -> Callable[..., GenCtxManager]:
     @contextlib.contextmanager
     def call(*args: Any, **kwargs: Any) -> Generator[list, Any, list]:
         ctxs = hook(*args, **kwargs)
+        if reverse:
+            ctxs = list(reversed(ctxs))
         with contextlib.ExitStack() as stack:
             yields = [stack.enter_context(ctx) for ctx in ctxs]
 
@@ -36,6 +48,16 @@ def call(*args: Any, **kwargs: Any) -> Generator[list, Any, list]:
             # `send()` and `throw()` and returns the return values of the
             # hook implementations.
 
+            # TODO: Stop yielding from _support_gen() and simply uncomment
+            # above `yield yields` as Nextline no longer uses `send()` or
+            # `throw()`. ExitStack correctly executes the code after the yield
+            # statement in the reverse order of entering the contexts and
+            # propagates exceptions from inner contexts to outer contexts.
+            # _support_gen() also executes the code after the first yield in
+            # the reverse order. However, it might not be the most sensible
+            # order if `send()` is used. _support_gen() doesn't propagate the
+            # exceptions in the same way as ExitStack.
+
             returns = yield from _support_gen(yields, ctxs)
         return returns
 
@@ -81,7 +103,7 @@ class _Context:
             raise
 
         yields = []
-        for c in contexts:
+        for c in reversed(contexts):  # close in the reversed order after yielding
             y = None
             if not c.stop_iteration:
                 try:

tests/plugins/test_call.py

@@ -41,11 +41,21 @@ def test_with(pm: PluginManager):
         assert r == [-1, -1, 3]
 
 
+def test_with_reverse(pm: PluginManager):
+    with pm.with_reverse.context(arg1=1, arg2=2) as r:
+        assert r == [3, -1, -1]
+
+
 async def test_awith(pm: PluginManager):
     async with pm.awith.acontext(arg1=1, arg2=2) as r:
         assert r == [-1, -1, 3]
 
 
+async def test_awith_reverse(pm: PluginManager):
+    async with pm.awith_reverse.acontext(arg1=1, arg2=2) as r:
+        assert r == [3, -1, -1]
+
+
 def test_name(pm: PluginManager):
     id_ = id(pm.list_name_plugin()[1][1])  # the object id of the 2nd plugin
 

tests/test_with_send_throw.py

@@ -265,7 +265,9 @@ def test_plugins(data: st.DataObject):
 
         for s, expected in zip(sends, yields_tr[1:]):
             yielded = c.gen.send(s)
-            assert expected == yielded
+            # assert expected == yielded
+            assert list(reversed(expected)) == yielded
+            # Reversed because the context managers are executed in the reverse order after yielding.
 
         if throw:
             thrown = Thrown()