Function use_debug_value

src/py/reactpy/reactpy/core/hooks.py:180–208

Log debug information when the given message changes. .. note:: This hook only logs if :data:`~reactpy.config.REACTPY_DEBUG_MODE` is active. Unlike other hooks, a message is considered to have changed if the old and new values are ``!=``. Because this comparison is performed on

(
    message: Any | Callable[[], Any],
    dependencies: Sequence[Any] | ellipsis | None = ...,
)

def use_debug_value(
    message: Any | Callable[[], Any],
    dependencies: Sequence[Any] | ellipsis | None = ...,
) -> None:
    """Log debug information when the given message changes.

    .. note::
        This hook only logs if :data:`~reactpy.config.REACTPY_DEBUG_MODE` is active.

    Unlike other hooks, a message is considered to have changed if the old and new
    values are ``!=``. Because this comparison is performed on every render of the
    component, it may be worth considering the performance cost in some situations.

    Parameters:
        message:
            The value to log or a memoized function for generating the value.
        dependencies:
            Dependencies for the memoized function. The message will only be recomputed
            if the identity of any value in the given sequence changes (i.e. their
            :func:`id` is different). By default these are inferred based on local
            variables that are referenced by the given function.
    """
    old: Ref[Any] = _use_const(lambda: Ref(object()))
    memo_func = message if callable(message) else lambda: message
    new = use_memo(memo_func, dependencies)

    if REACTPY_DEBUG_MODE.current and old.current != new:
        old.current = new
        logger.debug(f"{current_hook().component} {new}")


def create_context(default_value: _Type) -> Context[_Type]: