Modules for Shiny Express (#1220)

Co-authored-by: Winston Chang <winston@posit.co>

Author: jcheng5

shiny/express/__init__.py

@@ -11,6 +11,7 @@
 from .. import render
 from . import ui
 from ._is_express import is_express_app
+from ._module import module
 from ._output import (  # noqa: F401
     output_args,  # pyright: ignore[reportUnusedImport]
     suspend_display,  # pyright: ignore[reportUnusedImport] - Deprecated
@@ -29,6 +30,7 @@
     "wrap_express_app",
     "ui",
     "expressify",
+    "module",
 )
 
 # Add types to help type checkers

shiny/express/_mock_session.py

@@ -3,7 +3,7 @@
 import textwrap
 from typing import TYPE_CHECKING, Awaitable, Callable, cast
 
-from .._namespaces import Root
+from .._namespaces import Id, ResolvedId, Root
 from ..session import Inputs, Outputs, Session
 
 if TYPE_CHECKING:
@@ -21,8 +21,8 @@ class ExpressMockSession:
     the `app_opts()` function.
     """
 
-    def __init__(self):
-        self.ns = Root
+    def __init__(self, ns: ResolvedId = Root):
+        self.ns = ns
         self.input = Inputs({})
         self.output = Outputs(cast(Session, self), self.ns, outputs={})
 
@@ -39,6 +39,10 @@ def on_ended(
     ) -> Callable[[], None]:
         return lambda: None
 
+    def make_scope(self, id: Id) -> Session:
+        ns = self.ns(id)
+        return cast(Session, ExpressMockSession(ns))
+
     def __getattr__(self, name: str):
         raise AttributeError(
             textwrap.dedent(

shiny/express/_module.py

@@ -0,0 +1,35 @@
+import functools
+from typing import Callable, Concatenate, ParamSpec, TypeVar
+
+from ..module import Id
+from ..session._session import Inputs, Outputs, Session
+from ..session._utils import require_active_session, session_context
+from .expressify_decorator import expressify
+
+T = TypeVar("T")
+P = ParamSpec("P")
+R = TypeVar("R")
+
+__all__ = ("module",)
+
+
+def module(
+    fn: Callable[Concatenate[Inputs, Outputs, Session, P], R]
+) -> Callable[Concatenate[Id, P], R]:
+    fn = expressify(fn)
+
+    @functools.wraps(fn)
+    def wrapper(id: Id, *args: P.args, **kwargs: P.kwargs) -> R:
+        parent_session = require_active_session(None)
+        module_session = parent_session.make_scope(id)
+
+        with session_context(module_session):
+            return fn(
+                module_session.input,
+                module_session.output,
+                module_session,
+                *args,
+                **kwargs
+            )
+
+    return wrapper

shiny/render/renderer/_renderer.py

@@ -1,6 +1,16 @@
 from __future__ import annotations
 
-from typing import Any, Awaitable, Callable, Generic, Optional, TypeVar, Union, cast
+from typing import (
+    TYPE_CHECKING,
+    Any,
+    Awaitable,
+    Callable,
+    Generic,
+    Optional,
+    TypeVar,
+    Union,
+    cast,
+)
 
 from htmltools import MetadataNode, Tag, TagList
 
@@ -9,6 +19,9 @@
 from ..._utils import is_async_callable, wrap_async
 from ...types import Jsonifiable
 
+if TYPE_CHECKING:
+    from ...session import Session
+
 # TODO-barret-docs: Double check docs are rendererd
 # Missing first paragraph from some classes: Example: TransformerMetadata.
 # No init method for TransformerParams. This is because the `DocClass` object does not
@@ -204,6 +217,7 @@ def __init__(
         super().__init__()
 
         self._auto_registered: bool = False
+        self._session: Session | None = None
 
         # Must be done last
         if callable(_fn):
@@ -278,10 +292,13 @@ def tagify(self) -> DefaultUIFnResult:
         return rendered_ui
 
     def _render_auto_output_ui(self) -> DefaultUIFnResultOrNone:
-        return self.auto_output_ui(
-            # Pass the `@output_args(foo="bar")` kwargs through to the auto_output_ui function.
-            **self._auto_output_ui_kwargs,
-        )
+        from ...session import session_context
+
+        with session_context(self._session):
+            return self.auto_output_ui(
+                # Pass the `@output_args(foo="bar")` kwargs through to the auto_output_ui function.
+                **self._auto_output_ui_kwargs,
+            )
 
     # ######
     # Auto registering output
@@ -297,6 +314,7 @@ def _on_register(self) -> None:
             ns_name = session.output._ns(self.__name__)
             session.output.remove(ns_name)
             self._auto_registered = False
+            self._session = session
 
     def _auto_register(self) -> None:
         """
@@ -317,6 +335,7 @@ def _auto_register(self) -> None:
                 # We mark the fact that we're auto-registered so that, if an explicit
                 # registration now occurs, we can undo this auto-registration.
                 self._auto_registered = True
+                self._session = s
 
 
 # Not inheriting from `WrapAsync[[], IT]` as python 3.8 needs typing extensions that

shiny/session/_utils.py

@@ -71,7 +71,7 @@ def session_context(session: Optional[Session]):
     """
     token: Token[Session | None] = _current_session.set(session)
     try:
-        with namespace_context(session.ns if session else None):
+        with namespace_context(session.ns if session is not None else None):
             yield
     finally:
         _current_session.reset(token)