make it faster

reflex/components/base/bare.py

@@ -9,12 +9,23 @@ from reflex.components.tags import Tag
 from reflex.components.tags.tagless import Tagless
 from reflex.config import PerformanceMode, environment
 from reflex.utils import console
+from reflex.utils.decorator import once
 from reflex.utils.imports import ParsedImportDict
 from reflex.vars import BooleanVar, ObjectVar, Var
 from reflex.vars.base import VarData
 from reflex.vars.sequence import LiteralStringVar
 
 
+@once
+def performace_mode():
+    """Get the performance mode.
+
+    Returns:
+        The performance mode.
+    """
+    return environment.REFLEX_PERF_MODE.get()
+
+
 def validate_str(value: str):
     """Validate a string value.
 
@@ -24,7 +35,7 @@ def validate_str(value: str):
     Raises:
         ValueError: If the value is a Var and the performance mode is set to raise.
     """
-    perf_mode = environment.REFLEX_PERF_MODE.get()
+    perf_mode = performace_mode()
     if perf_mode != PerformanceMode.OFF and value.startswith("reflex___state"):
         if perf_mode == PerformanceMode.WARN:
             console.warn(

reflex/utils/decorator.py

@@ -0,0 +1,25 @@
+"""Decorator utilities."""
+
+from typing import Callable, TypeVar
+
+T = TypeVar("T")
+
+
+def once(f: Callable[[], T]) -> Callable[[], T]:
+    """A decorator that calls the function once and caches the result.
+
+    Args:
+        f: The function to call.
+
+    Returns:
+        A function that calls the function once and caches the result.
+    """
+    unset = object()
+    value: object | T = unset
+
+    def wrapper() -> T:
+        nonlocal value
+        value = f() if value is unset else value
+        return value  # pyright: ignore[reportReturnType]
+
+    return wrapper

tests/units/test_var.py

@@ -1896,18 +1896,25 @@ def test_var_data_with_hooks_value():
     assert var_data == VarData(hooks=["what", "whot", "whott"])
 
 
-def test_str_var_in_components():
+def test_str_var_in_components(mocker):
-    from reflex.config import environment
-
-    current_performance_mode = environment.REFLEX_PERF_MODE.get()
-    environment.REFLEX_PERF_MODE.set(PerformanceMode.RAISE)
-
     class StateWithVar(rx.State):
         field: int = 1
 
+    mocker.patch(
+        "reflex.components.base.bare.performace_mode",
+        lambda: PerformanceMode.RAISE,
+    )
+
     with pytest.raises(ValueError):
         rx.vstack(
             str(StateWithVar.field),
         )
 
-    environment.REFLEX_PERF_MODE.set(current_performance_mode)
+    mocker.patch(
+        "reflex.components.base.bare.performace_mode",
+        lambda: PerformanceMode.OFF,
+    )
+
+    rx.vstack(
+        str(StateWithVar.field),
+    )