use_state

Returns a (value, setter) tuple that is used to manage state in a component.

def use_state(initial: T, key: str = None, eq: Callable[[Any, Any], bool] = None) -> Tuple[T, Callable[[Union[T, Callable[[T], T]]], None]]:

    ...

This function can only be called from a component function.

The value returns the current state (which equals initial at the first render call). Or the value that was last set using the setter.

Note that the setter function can be used in two ways.

Directly setting the value:

@reacton.component
def ButtonClick():
    clicks, set_clicks = reacton.use_state(0)
    def my_click_handler():
        set_clicks(clicks+1)
    button = w.Button(description=f"Clicked {clicks} times",
                    on_click=my_click_handler)
    return button

Updating the value based on the previous/current value.

@reacton.component
def ButtonClick():
    clicks, set_clicks = reacton.use_state(0)
    def my_click_handler():
        set_clicks(lambda prev: prev+1)
    button = w.Button(description=f"Clicked {clicks} times",
                    on_click=my_click_handler)
    return button

The last one avoid issues with stale data, which means you have a reference to the value of an old render pass (not present in this simple example).

use_state