refactor(memo): promote memo out of rx._x.memo into rx.memo

[FarhanAliRaza]

All Submissions:

Summary

Promotes the memo system out of rx._x into a first-class rx.memo API,
with rx._x.memo kept as a thin deprecated alias so downstream apps
keep working.

• Move the memo implementation from reflex/experimental/memo.py into
  packages/reflex-base/src/reflex_base/components/memo.py
  and re-export it as rx.memo; the old module becomes a deprecation
  shim that re-exports the same symbols.

• Drop the Experimental prefix on the registry and public types so
  rx.memo reads cleanly without leaking the old namespace.

• Support rx.EventHandler parameters in component memos and annotate
  return types so rx.memo-decorated callables type-check at call sites.

• Expose EMPTY_VAR_STR / EMPTY_VAR_INT as memo-friendly sentinel
  defaults to replace ad-hoc empty-var construction in callers.

• Migrate the existing Selenium memo integration test to Playwright
  under tests/integration/tests_playwright/test_memo.py;
  the legacy test_experimental_memo.py is retired and the remaining
  test_memo.py exercises the deprecation shim path.

• Update docs and internal component packages to use rx.memo directly.

• Have you followed the guidelines stated in CONTRIBUTING.md file?

• Have you checked to ensure there aren't any other open Pull Requests for the desired changed?

Type of change

Please delete options that are not relevant.

• New feature (non-breaking change which adds functionality)

• This change requires a documentation update

New Feature Submission:

• Does your submission pass the tests?
• Have you linted your code locally prior to submission?

Changes To Core Features:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your core changes, as applicable?
• Have you successfully ran tests with your changes locally?

fixes ENG-9486

[greptile-apps]

Greptile Summary

This PR promotes rx.memo from rx._x.memo (experimental) to a first-class public API. The implementation moves the memo engine into reflex_base.components.memo, drops the Experimental prefix from internal types, adds EventHandler parameter support, exposes EMPTY_VAR_STR/EMPTY_VAR_INT sentinels, and migrates the integration test suite from Selenium to Playwright.

• The old reflex.experimental.memo module is replaced by a one-liner shim that swaps itself in sys.modules for reflex_base.components.memo, ensuring from reflex.experimental.memo import memo continues to work while firing a deprecation warning at import time.
• rx._x.memo is kept alive as a @property on ExperimentalNamespace that warns on access and returns the same underlying decorator, preserving backward compatibility.
• The compiler pipeline is simplified: compile_memo_components now takes a single memos iterable (dropping the parallel CustomComponent path), and the legacy compile_custom_component helper is removed.

Confidence Score: 4/5

Safe to merge after fixing the misleading error messages in memo.py that still point users to the deprecated rx._x.memo namespace.

The memo engine works correctly and the deprecation shim is well-structured. However, all user-facing TypeError messages in packages/reflex-base/src/reflex_base/components/memo.py still say @rx._x.memo — so every validation error a @rx.memo user hits will tell them to use the old, deprecated decorator instead of the canonical one.

packages/reflex-base/src/reflex_base/components/memo.py — ~12 error-message strings reference @rx._x.memo instead of @rx.memo.

Important Files Changed

Filename	Overview
packages/reflex-base/src/reflex_base/components/memo.py	New canonical memo implementation (1549 lines); all user-facing error messages still say @rx._x.memo instead of @rx.memo, and MemoParam/MemoParamKind are absent from all.
reflex/experimental/memo.py	Reduced to a deprecation shim that replaces itself in sys.modules with reflex_base.components.memo; correctly triggers a deprecation warning at import time.
reflex/experimental/init.py	Replaces the static memo=memo kwarg with a @Property on ExperimentalNamespace that fires a deprecation warning on access; clean implementation.
reflex/compiler/compiler.py	Drops legacy CustomComponent/CUSTOM_COMPONENTS path; compile_memo_components now takes a single memos iterable using MEMOS and auto_memo_components.
reflex/compiler/utils.py	Removes compile_custom_component and imports from experimental; updates compile_experimental_component_memo to use MemoComponentDefinition and MemoParamKind.
reflex/init.py	Moves memo lazy-load mapping from component.py to memo.py and adds EMPTY_VAR_STR/EMPTY_VAR_INT to the public rx namespace.
packages/reflex-base/src/reflex_base/vars/base.py	Adds EMPTY_VAR_STR and EMPTY_VAR_INT sentinel constants for memo default values.
tests/units/components/test_memo.py	New comprehensive unit-test suite covering var memos, component memos with children/rest/EventHandler, compile paths, and deprecation shim.
tests/integration/tests_playwright/test_memo.py	New Playwright integration test replacing the retired Selenium test_experimental_memo.py; exercises the full rx.memo compile-and-render path.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A["@rx.memo decorator"] --> B{Return type annotation}
    B -->|"rx.Component"| C["_create_component_definition()"]
    B -->|"rx.Var[T]"| D["_create_function_definition()"]
    B -->|"missing / other"| E["TypeError raised"]
    C --> F["_register_memo_definition()\nMEMOS registry"]
    D --> F
    F --> G["_create_component_wrapper()\n→ _MemoComponentWrapper"]
    F --> H["_create_function_wrapper()\n→ _MemoFunctionWrapper"]
    G --> I["User calls wrapper(...)"]
    H --> I
    I --> J["_bind_value / _bind_event_trigger\nper MemoParam"]
    J --> K["MemoComponent._create()"]
    F --> L["compile_memo_components()\nMEMOS.values()"]
    L -->|"MemoComponentDefinition"| M["compile_experimental_component_memo()"]
    L -->|"MemoFunctionDefinition"| N["compile_experimental_function_memo()"]
    M --> O[".jsx file per memo"]
    N --> O
    P["rx._x.memo property"] -->|"deprecation warning"| A
    Q["from reflex.experimental.memo import memo\nsys.modules swap"] -->|"deprecation warning at import"| A

Loading

_{Reviews (2): Last reviewed commit: "chore(memo): tidy compile_app splats and..." | Re-trigger Greptile}

[codspeed-hq]

Merging this PR will not alter performance

✅ 24 untouched benchmarks

---

_{Comparing FarhanAliRaza:non-exp-memo (8f6cd8a) with main (bf2deed)}

[masenf]

hitting a problem with recursive components

from collections.abc import Sequence
from typing import TypedDict

import reflex as rx


class TreeNode(TypedDict):
    name: str
    children: Sequence["TreeNode"]


class State(rx.State):
    """The app state."""

    tree: TreeNode = TreeNode(
        name="root",
        children=[
            TreeNode(name="child1", children=[]),
            TreeNode(
                name="child2", children=[TreeNode(name="grandchild1", children=[])]
            ),
        ],
    )


@rx._x.memo
def node_x(data: rx.vars.ObjectVar[TreeNode]) -> rx.Component:
    return rx.vstack(
        rx.text(data.name),
        rx.foreach(data.children, lambda child: node_x(data=child)),
        class_name="pl-4 border-l",
    )


@rx.memo
def node(data: rx.vars.ObjectVar[TreeNode]) -> rx.Component:
    return rx.vstack(
        rx.text(data.name),
        rx.foreach(data.children, lambda child: node(data=child)),
        class_name="pl-4 border-l",
    )


def index() -> rx.Component:
    return rx.container(
        rx.color_mode.button(position="top-right"),
        rx.vstack(
            rx.heading("Welcome to Reflex!", size="9"),
            node(data=State.tree),
            spacing="5",
            justify="center",
            min_height="85vh",
        ),
    )


app = rx.App()
app.add_page(index)

if you comment out the @rx._x.memo on node_x, the app will run with the old memo component and work as expected.

[FarhanAliRaza]

Warning for deprecation.

[masenf]

seems this could just be removed?