improve var base typing (#4718)

* improve var base typing

* fix pyi

* dang it darglint

* drain _process in tests

* fixes #4576

* dang it darglint

reflex/components/base/error_boundary.py

@@ -11,10 +11,11 @@
 from reflex.state import FrontendEventExceptionState
 from reflex.vars.base import Var
 from reflex.vars.function import ArgsFunctionOperation
+from reflex.vars.object import ObjectVar
 
 
 def on_error_spec(
-    error: Var[Dict[str, str]], info: Var[Dict[str, str]]
+    error: ObjectVar[Dict[str, str]], info: ObjectVar[Dict[str, str]]
 ) -> Tuple[Var[str], Var[str]]:
     """The spec for the on_error event handler.
 

reflex/components/base/error_boundary.pyi

@@ -9,9 +9,10 @@ from reflex.components.component import Component
 from reflex.event import BASE_STATE, EventType
 from reflex.style import Style
 from reflex.vars.base import Var
+from reflex.vars.object import ObjectVar
 
 def on_error_spec(
-    error: Var[Dict[str, str]], info: Var[Dict[str, str]]
+    error: ObjectVar[Dict[str, str]], info: ObjectVar[Dict[str, str]]
 ) -> Tuple[Var[str], Var[str]]: ...
 
 class ErrorBoundary(Component):

reflex/components/component.py

@@ -2457,6 +2457,7 @@ def render_dict_to_var(tag: dict | Component | str, imported_names: set[str]) ->
 @dataclasses.dataclass(
     eq=False,
     frozen=True,
+    slots=True,
 )
 class LiteralComponentVar(CachedVarOperation, LiteralVar, ComponentVar):
     """A Var that represents a Component."""

reflex/components/core/foreach.py

@@ -11,6 +11,7 @@
 from reflex.components.tags import IterTag
 from reflex.constants import MemoizationMode
 from reflex.state import ComponentState
+from reflex.utils.exceptions import UntypedVarError
 from reflex.vars.base import LiteralVar, Var
 
 
@@ -51,6 +52,7 @@ def create(
         Raises:
             ForeachVarError: If the iterable is of type Any.
             TypeError: If the render function is a ComponentState.
+            UntypedVarError: If the iterable is of type Any without a type annotation.
         """
         iterable = LiteralVar.create(iterable)
         if iterable._var_type == Any:
@@ -72,8 +74,14 @@ def create(
             iterable=iterable,
             render_fn=render_fn,
         )
-        # Keep a ref to a rendered component to determine correct imports/hooks/styles.
-        component.children = [component._render().render_component()]
+        try:
+            # Keep a ref to a rendered component to determine correct imports/hooks/styles.
+            component.children = [component._render().render_component()]
+        except UntypedVarError as e:
+            raise UntypedVarError(
+                f"Could not foreach over var `{iterable!s}` without a type annotation. "
+                "See https://reflex.dev/docs/library/dynamic-rendering/foreach/"
+            ) from e
         return component
 
     def _render(self) -> IterTag:

reflex/components/datadisplay/dataeditor.py

@@ -387,7 +387,8 @@ def create(cls, *children, **props) -> Component:
                 raise ValueError(
                     "DataEditor data must be an ArrayVar if rows is not provided."
                 )
-            props["rows"] = data.length() if isinstance(data, Var) else len(data)
+
+            props["rows"] = data.length() if isinstance(data, ArrayVar) else len(data)
 
         if not isinstance(columns, Var) and len(columns):
             if types.is_dataframe(type(data)) or (

reflex/components/datadisplay/shiki_code_block.py

@@ -621,18 +621,22 @@ def add_imports(self) -> dict[str, list[str]]:
 
         Returns:
             Imports for the component.
+
+        Raises:
+            ValueError: If the transformers are not of type LiteralVar.
         """
         imports = defaultdict(list)
+        if not isinstance(self.transformers, LiteralVar):
+            raise ValueError(
+                f"transformers should be a LiteralVar type. Got {type(self.transformers)} instead."
+            )
         for transformer in self.transformers._var_value:
             if isinstance(transformer, ShikiBaseTransformers):
                 imports[transformer.library].extend(
                     [ImportVar(tag=str(fn)) for fn in transformer.fns]
                 )
-                (
+                if transformer.library not in self.lib_dependencies:
                     self.lib_dependencies.append(transformer.library)
-                    if transformer.library not in self.lib_dependencies
-                    else None
-                )
         return imports
 
     @classmethod

reflex/event.py

@@ -4,7 +4,6 @@
 
 import dataclasses
 import inspect
-import sys
 import types
 import urllib.parse
 from base64 import b64encode
@@ -541,7 +540,7 @@ class JavasciptKeyboardEvent:
     shiftKey: bool = False  # noqa: N815
 
 
-def input_event(e: Var[JavascriptInputEvent]) -> Tuple[Var[str]]:
+def input_event(e: ObjectVar[JavascriptInputEvent]) -> Tuple[Var[str]]:
     """Get the value from an input event.
 
     Args:
@@ -562,7 +561,9 @@ class KeyInputInfo(TypedDict):
     shift_key: bool
 
 
-def key_event(e: Var[JavasciptKeyboardEvent]) -> Tuple[Var[str], Var[KeyInputInfo]]:
+def key_event(
+    e: ObjectVar[JavasciptKeyboardEvent],
+) -> Tuple[Var[str], Var[KeyInputInfo]]:
     """Get the key from a keyboard event.
 
     Args:
@@ -572,15 +573,15 @@ def key_event(e: Var[JavasciptKeyboardEvent]) -> Tuple[Var[str], Var[KeyInputInf
         The key from the keyboard event.
     """
     return (
-        e.key,
+        e.key.to(str),
         Var.create(
             {
                 "alt_key": e.altKey,
                 "ctrl_key": e.ctrlKey,
                 "meta_key": e.metaKey,
                 "shift_key": e.shiftKey,
             },
-        ),
+        ).to(KeyInputInfo),
     )
 
 
@@ -1354,7 +1355,7 @@ def unwrap_var_annotation(annotation: GenericType):
     Returns:
         The unwrapped annotation.
     """
-    if get_origin(annotation) is Var and (args := get_args(annotation)):
+    if get_origin(annotation) in (Var, ObjectVar) and (args := get_args(annotation)):
         return args[0]
     return annotation
 
@@ -1620,7 +1621,7 @@ class EventVar(ObjectVar, python_types=EventSpec):
 @dataclasses.dataclass(
     eq=False,
     frozen=True,
-    **{"slots": True} if sys.version_info >= (3, 10) else {},
+    slots=True,
 )
 class LiteralEventVar(VarOperationCall, LiteralVar, EventVar):
     """A literal event var."""
@@ -1681,7 +1682,7 @@ class EventChainVar(BuilderFunctionVar, python_types=EventChain):
 @dataclasses.dataclass(
     eq=False,
     frozen=True,
-    **{"slots": True} if sys.version_info >= (3, 10) else {},
+    slots=True,
 )
 # Note: LiteralVar is second in the inheritance list allowing it act like a
 # CachedVarOperation (ArgsFunctionOperation) and get the _js_expr from the
@@ -1713,6 +1714,9 @@ def create(
 
         Returns:
             The created LiteralEventChainVar instance.
+
+        Raises:
+            ValueError: If the invocation is not a FunctionVar.
         """
         arg_spec = (
             value.args_spec[0]
@@ -1740,6 +1744,11 @@ def create(
         else:
             invocation = value.invocation
 
+        if invocation is not None and not isinstance(invocation, FunctionVar):
+            raise ValueError(
+                f"EventChain invocation must be a FunctionVar, got {invocation!s} of type {invocation._var_type!s}."
+            )
+
         return cls(
             _js_expr="",
             _var_type=EventChain,

reflex/experimental/client_state.py

@@ -4,7 +4,6 @@
 
 import dataclasses
 import re
-import sys
 from typing import Any, Callable, Union
 
 from reflex import constants
@@ -49,7 +48,7 @@ def _client_state_ref_dict(var_name: str) -> str:
 @dataclasses.dataclass(
     eq=False,
     frozen=True,
-    **{"slots": True} if sys.version_info >= (3, 10) else {},
+    slots=True,
 )
 class ClientStateVar(Var):
     """A Var that exists on the client via useState."""

reflex/state.py

@@ -1637,9 +1637,11 @@ async def get_var_value(self, var: Var[VAR_TYPE]) -> VAR_TYPE:
         if not isinstance(var, Var):
             return var
 
+        unset = object()
+
         # Fast case: this is a literal var and the value is known.
-        if hasattr(var, "_var_value"):
-            return var._var_value
+        if (var_value := getattr(var, "_var_value", unset)) is not unset:
+            return var_value  # pyright: ignore [reportReturnType]
 
         var_data = var._get_all_var_data()
         if var_data is None or not var_data.state:

reflex/utils/exceptions.py

@@ -75,6 +75,10 @@ class VarAttributeError(ReflexError, AttributeError):
     """Custom AttributeError for var related errors."""
 
 
+class UntypedVarError(ReflexError, TypeError):
+    """Custom TypeError for untyped var errors."""
+
+
 class UntypedComputedVarError(ReflexError, TypeError):
     """Custom TypeError for untyped computed var errors."""