Function _hotswap

src/py/reactpy/reactpy/testing/backend.py:159–227

Swap out components from a layout on the fly. Since you can't change the component functions used to create a layout in an imperative manner, you can use ``hotswap`` to do this so long as you set things up ahead of time. Parameters: update_on_change: Whether or not all view

(update_on_change: bool = False)

def _hotswap(update_on_change: bool = False) -> tuple[_MountFunc, ComponentConstructor]:
    """Swap out components from a layout on the fly.

    Since you can't change the component functions used to create a layout
    in an imperative manner, you can use ``hotswap`` to do this so
    long as you set things up ahead of time.

    Parameters:
        update_on_change: Whether or not all views of the layout should be updated on a swap.

    Example:
        .. code-block:: python

            import reactpy

            show, root = reactpy.hotswap()
            PerClientStateServer(root).run_in_thread("localhost", 8765)

            @reactpy.component
            def DivOne(self):
                return {"tagName": "div", "children": [1]}

            show(DivOne)

            # displaying the output now will show DivOne

            @reactpy.component
            def DivTwo(self):
                return {"tagName": "div", "children": [2]}

            show(DivTwo)

            # displaying the output now will show DivTwo
    """
    constructor_ref: Ref[Callable[[], Any]] = Ref(lambda: None)

    if update_on_change:
        set_constructor_callbacks: set[Callable[[Callable[[], Any]], None]] = set()

        @component
        def HotSwap() -> Any:
            # new displays will adopt the latest constructor and arguments
            constructor, _set_constructor = use_state(lambda: constructor_ref.current)
            set_constructor = use_callback(lambda new: _set_constructor(lambda _: new))

            def add_callback() -> Callable[[], None]:
                set_constructor_callbacks.add(set_constructor)
                return lambda: set_constructor_callbacks.remove(set_constructor)

            use_effect(add_callback)

            return constructor()

        def swap(constructor: Callable[[], Any] | None) -> None:
            constructor = constructor_ref.current = constructor or (lambda: None)

            for set_constructor in set_constructor_callbacks:
                set_constructor(constructor)